Antimicrobial plastics and stickers

Abstract

Described herein are plastic carriers having antimicrobial properties, as well as compositions (e.g., masterbatches) and methods for producing such plastic carriers. In some embodiments, the plastic carrrier comprises potassium metabisulfite, which imparts antimicrobial properties to the plastics.

Description

ANTIMICROBIAL PLASTICS AND STICKERS

[0001] This application claims priority from US 63 / 729,125 filed on 06 December 2024.BACKGROUND

[0002] Modem agriculture and food industries have high demand for materials and devices that can protect their products from contamination and spoilage resulting from microbes (e.g., bacteria, fungi, and viruses). Agricultural and food products with high water content can release moisture that is trapped inside their containers, accelerating the microbe growth and the spoilage process. Effective control or killing of microbes in such conditions will significantly increase the shelf life of agricultural and food products, leading to improved food qualities (e.g., freshness, taste, flavor, color) and reduced waste.

[0003] There is a need for improved materials, devices, and methods for controlling and killing microbes and extending the shelflife of food products. The present disclosure provides such materials, devices, their uses, and more.SUMMARY

[0004] In one aspect, the disclosure provides plastic carriers comprising potassium metabisulfite. In some embodiments, the plastic carrier comprises about 0.1% (w / w) to about 50% (w / w) potassium metabisulfite based on the weight of the plastic carrier. In some embodiments, the plastic carrier comprises about 1% (w / w) to about 40% (w / w), about 5% (w / w) to about 30% (w / w), or about 15% (w / w) to about 25% (w / w) potassium metabisulfite based on the weight of the plastic carrier.

[0005] In some embodiments, at least a portion of the potassium metabisulfite is present on at least one surface of the plastic carrier. In some embodiments, at least a portion of the potassium metabisulfite is present in the bulk of the plastic carrier.

[0006] In some embodiments, the potassium metabisulfite is in a powdered form. In some embodiments, the plastic carrier comprises granules comprising potassium metabisulfite. In some embodiments, the granules have an average size of about 1-200 pm when measured using Malvern Laser Diffractometer. In some embodiments, the granules have an average size of about 1-50 pm when measured using a Malvern Laser Diffractometer.

[0007] In some embodiments, the plastic carrier has a pH of from about 6.5 to about 7.5. In some embodiments, the plastic carrier emits an effective amount of sulfur dioxide (SO2).

[0008] In some embodiments, the potassium metabisulfite is not encapsulated in a metal oxide or silica. In some embodiments, all or substantially all of the potassium metabisulfite is in direct contact with the plastic carrier.

[0009] In some embodiments, the plastic carrier is in the format of a film, a sticker, a fiber, a foam, a disc, a box, a lid, a punnet, or a container.

[0010] In some embodiments, a first surface of the plastic carrier comprises the potassium metabisulfite and the first surface comprises a surface area of at least 1 cm2. In some embodiments, the surface area of the first surface of the plastic carrier is 1 cm2to about 100 cm2. In some embodiments, the surface area of the first surface of the plastic carrier is no more than 50 cm2.

[0011] In some embodiments, the plastic carrier comprises thickness of between 100 pm and 1.5 mm. In some embodiments, the plastic carrier comprises volume of between 1 cm3and 100 cm3. In some embodiments, the plastic carrier has a surface-to-volume ratio ranging from 10 cm^(-1) to 5,000 cm^(-1).

[0012] In some embodiments, the plastic carrier further comprises a second surface and an adhesive material on the second surface of the plastic carrier.

[0013] In some embodiments, the plastic is a food grade plastic.

[0014] In some embodiments, the plastic is capable of injection molding at a temperature of up to 250°C. In some embodiments, the plastic is capable of injection molding at a temperature of between 150°C and 250°C.

[0015] In some embodiments, the plastic is gas permeable.

[0016] In some embodiments, the plastic carrier comprises a plastic material selected from a polyolefin, polyester, acrylic or an ester derivative thereof, polyolefin elastomer, thermoplastic elastomer, elastomer, and combinations thereof. In some embodiments, the plastic material comprises a polyolefin, polyester, or copolymers thereof. In some embodiments, the plastic material comprises a polyolefin, polyester, polyoxymethylene (POM), polyvinylidene fluoride (PVDF), polymethylmethacrylate (PMMA), polystyrene (PS), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), ethylene-vinyl acetate (EVA), ethylene methyl acrylate (EMA), polyvinyl alcohol (PVA), styrene acrylonitrile resin (SAN), or any combinations thereof. In some embodiments, the plastic material comprises a polyethylene (PE) or polypropylene (PP). In some embodiments, the polyethylene comprises ultra-high molecular weight polyethylene (UHMWPE), high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), or low density polyethylene (LDPE).

[0017] In some embodiments, the plastic carrier is degradable. In some embodiments, the plastic carrier comprises polylactic acid (PLA), polycaprolactone (PCL), polyglycolide (PGA), or poly(lactide-co-glycolide) (PLGA).

[0018] In some embodiments, the plastic carrier extends shelf life of a food product by at least 3 days when measured at 20 °C. In some embodiments, the plastic carrier extends shelf life of a food product by 3-50 days when measured at 20 °C. In some embodiments, the food product is a fruit or vegetable. In some embodiments, the fruit is strawberry, blueberry, raspberry, or grape.

[0019] In some embodiments, food migration of potassium metabisulfite is less than 0.01 mg / kg as measured using TES-AC-812, a contact time of 10 days, and temperature of 40 °C. In some embodiments, food migration of SO2 is less than 0.001 mg / kg as measured using TES-AC-812, a contact time of 10 days, and temperature of 40 °C.

[0020] In one aspect, the disclosure provides methods of manufacturing a plastic carrier, comprising: (a) mixing (i) a masterbatch comprising a first plastic material and about 20% (w / w) to about 80% (w / w) potassium metabisulfite; and (ii) a second plastic material, to form a mixture; and (b) subjecting the mixture to a temperature of between 50 °C and 250 °C, to form the plastic carrier. In some embodiments, the method further comprises attaching the plastic carrier to a containing comprising a food product.

[0021] In some embodiments, the plastic carrier is made by a process comprising steps of:(a) mixing (i) a masterbatch comprising a first plastic material and about 20% (w / w) to about 80% (w / w) potassium metabisulfite; and (ii) a second plastic material, to form a mixture; and (b) subjecting the mixture to a temperature of between 50 °C and 250 °C, to form the plastic carrier.

[0022] In some embodiments, the temperature in step (b) is between 150 and 190 °C. In some embodiments, the temperature in step (b) is no more than 230 °C.

[0023] In some embodiments, the method or process further comprises (c) applying an adhesive material to the surface of the plastic carrier.

[0024] In one aspect, the disclosure provides containers comprising the plastic carrier of the disclosure. In some embodiments, the container is a sealed container. In some embodiments, the ratio of the exposed surface area of the plastic carrier and the volume of the interior of the container ranges from 0.001 cmA(-l) to 0.5 cmA(-l). In some embodiments, the container has undergone modified atmosphere packaging.

[0025] In some embodiments, the container comprises a fruit or vegetable in its interior. In some embodiments, shelf life of the fruit or vegetable is extended by at least 3 days,compared to shelf life of the fruit or vegetable without the plastic carrier at 20 °C. In some embodiments, shelflife of the fruit or vegetable is extended by 3-50 days at 20 °C, compared to shelflife of the fruit or vegetable without the plastic carrier at 20 °C. In some embodiments, the fruit is strawberry, blueberry, raspberry, or grape.

[0026] In some embodiments, the plastic carrier is in the interior of the container.

[0027] In one aspect, the disclosure provides methods of controlling or killing a microbe on a product, comprising (i) placing the plastic carrier of the disclosure in proximity to the product or (ii) contacting the plastic carrier with the product. In some embodiments, the plastic carrier is within 20 cm to the nearest surface of the product. In some embodiments, the product is a food product.BRIEF DESCRIPTION OF THE FIGURES

[0028] Figure 1 shows the number of rejected punnets during 14 days of experiments for P (control) and K samples.

[0029] Figure 2 shows SEM images of the ground potassium metabisulfite (KMB) powder having Dv (95) 9.536 um (left), Dv (95) 25.588 um (middle), and Dv (95) 42.232 um (right). Dv (95) represents the 95% of particles in a powder that are smaller than this size.

[0030] Figure 3 shows representative TGA thermograms of potassium metabisulfite (KMB-powder) and 20% KMB thin film. Solid lines represent KMB powder data, and dashed lines represent 20% KMB thin film data.

[0031] Figure 4 shows representative TGA thermograms of potassium metabisulfite (KMB-powder) and 15% KMB thin film. Solid lines represent KMB powder data, and dashed lines represent 15% KMB thin film data.

[0032] Figure 5 shows antibacterial activity of potassium metabisulfite (KMB) incorporated PP films against the gram-negative bacterium Escherichia coli in a direct contact killing assay. Two film thicknesses and multiple KMB concentrations in the thin film (5-20%) were tested. All samples exhibited around 6 logs (99.9999%) reduction compared with PP controls.

[0033] Figure 6 shows activity of potassium metabisulfite (KMB) incorporated PP films against the gram-positive bacterium Staphylococcus aureus in an indirect killing assay, which analyzed the antibacterial activity of the KMB powder, 5% thin film, and 20% thin film according to an indirect killing experiment designed for volatile molecules. All samples exhibited full inhibition as compared to control.

[0034] Figure 7 shows the accumulative numbers of rejected punnets during 22 days of experiments for PP film (control) as well as the thick and thin films. Test groups 1-6 are described in detail in the Examples section.

[0035] Figure 8A-8B are charts showing the antibacterial activity against Staphylococcus aureus (Figure 8 A) and Escherichia coli (Figure 8B) of 0.5 wt%, 2.5 wt% and 5 wt% potassium metabisulfite in low-density polyethylene (LDPE) thick films compared to an untreated control sample. Asterisks indicate full inhibition of bacterial growth.

[0036] Figure 9 is a chart showing the antibacterial activity against Staphylococcus aureus of 0.5 wt%, 1%, 2 wt% and 5 wt% potassium metabisulfite in polypropylene (PP) thick films compared to an untreated control sample and a commercially available silver formulation with a 20 wt% loading.

[0037] Figures 10A-10B are charts showing the antibacterial activity against Staphylococcus aureus (Figure 10A) and Escherichia coli (Figure 10B) of potassium and sodium metabisulfite carried in an ethylene-vinyl acetate (EVA) masterbatch at 20 wt%, which was diluted into PP to 2 wt% and 5 wt% at final concentration. Asterisks indicate full inhibition of bacterial growth.

[0038] Figure 11 is a chart showing the antifungal activity of potassium metabisulfite (1% (left hand column) and 2% (right column)) carried in PP thick films against the yeast Candida albicans and the mold Aspergillus brasiliensis within 24 hours of contact time.

[0039] Figure 12 shows the individual assessment of the panelist for 5-20% KMB thin film containing punnets.

[0040] Figure 13 shows microbiology data comparing KMB vs NaMB (both at 20% weight / weight) in LDPE. This Microbiology data shows the slower release of SO2 from KMB.DETAILED DESCRIPTION OF THE DISCLOSUREDefinitions

[0041] The indefinite articles “a” and “an” and the definite article “the” are intended to include both the singular and the plural, unless the context in which they are used clearly indicates otherwise.

[0042] “At least one” and “one or more” are used interchangeably to mean that the article may include one or more than one of the listed elements.

[0043] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0044] It is understood that aspects and embodiments of the disclosure described herein include “comprising,” “consisting,” and “consisting essentially of’ aspects and embodiments. Any recitation herein of the term “comprising”, particularly in a description of components of a composition or in a description of steps of a method, is understood to encompass those compositions and methods consisting essentially of or consisting of the recited components or step.

[0045] Unless otherwise indicated, it is to be understood that all numbers expressing quantities, ratios, and numerical properties of ingredients, reaction conditions, and so forth, used in the specification and claims are contemplated to be able to be modified in all instances by the term “about”.

[0046] Throughout this application, the term “about” is used to indicate that a value includes the acceptable variation of error for the device or the method being employed to determine the value, or the variation that exists among the samples being measured. In embodiments, the term “about” means within 10% above or below the reported numerical value (except where such a number would exceed 100% of a possible value or go below 0%). When used in conjunction with a range or series of values, the term “about” applies to the endpoints of the range or each of the values enumerated in the series, unless otherwise indicated. As used in this application, the terms “about” and “approximately” are used as equivalents.

[0047] Ranges in this document should be understood to be inclusive of their end points, unless otherwise indicated. A content range of 1-5% w / w of an ingredient, for example, includes contents of 1.0% w / w and 5.0% w / w. And the term “between” when used in reference to a range includes the endpoint numbers on both limits of the range — for example, a content between about 1% w / w and about 5% w / w of an ingredient, includes about 1.0% w / w and about 5.0% w / w. Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and are also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits (e.g., as described by “ranging from” or “between”), ranges excluding either or both of those included limits are also included in the disclosure.

[0048] The term “including all ranges and subranges therebetween” or equivalents, are used herein to denote the intention that disclosure of any range or series of possible values, necessarily also discloses all ranges and subranges encompassed by the highest and lowestvalues disclosed. This term includes the entire range from highest to lowest disclosed values, as well as subranges from any two or more disclosed points. This term is also intended to disclose any subranges encompassed anywhere within the highest and lowest disclosed values, including between two points that are explicitly recited in the document, up to one decimal point. Thus, disclosure of values 0, 5, 10, 15, 20, including all ranges and subranges therebetween, should be interpreted as also encompassing a range from 0-20, a range from 0-5 or 5-15, as well as a range from 2-16, or 3.1 to 19.8, etc.

[0049] Unless otherwise indicated, it is to be understood that all numbers expressing quantities, ratios, and numerical properties of ingredients, reaction conditions, and so forth, used in the specification are contemplated to be able to be modified in all instances by the term “including all ranges and subranges therebetween”.

[0050] The term “antimicrobial property” or “antimicrobial effect” refers to inhibiting or preventing growth of, or killing, microorganisms including bacteria, fungi and viruses.Overview

[0051] In one aspect, the present disclosure relates to plastic carriers that possess antimicrobial properties. In some embodiments, the antimicrobial properties are imparted, at least in part, by the presence of an effective amount of potassium metabisulfite in the plastic carrier. Potassium metabisulfite is a food additive, which releases sulfur dioxide (SO2) that kills or slows the growth of microbes, especially bacteria and fungi. In some embodiments, the antimicrobial property is imparted by potassium metabisulfite as the single active agent used in the manufacture of the plastic carriers. In some embodiments, the plastic carriers of the disclosure display antimicrobial efficacy against both gram-negative and gram-positive bacteria, is cost-effective, and is safe for food. In some embodiments, the plastic carriers of the disclosure display antifungal efficacy against a fungus. In some embodiments, the fungus comprises a yeast. In some embodiments, the fungus comprises a mold. In some embodiments, the plastic carriers of the disclosure display antifungal efficacy against both a mold and a yeast.

[0052] In some embodiments, the present disclosure relates to plastic carriers comprising: (i) a thermoplastic or thermoplastic elastomer material; and (ii) potassium metabisulfite. In some embodiments, the potassium metabisulfite is in a solid or dry form and the plastic carrier has a substantially neutral pH (e.g., a pH ranging from about 6.5 to about 7.5).

[0053] The use of potassium metabisulfite as the antimicrobial agent in a plastic carrier is counterintuitive. As an initial matter, potassium metabisulfite is known to decompose at a temperature of above 150°C, but the production of various thermoplastic plastic carriersrequires a temperature higher than 150°C. Surprisingly, as shown herein, potassium metabisulfite was incorporated into plastic carriers using substantially higher injection molding temperatures and observed antimicrobial efficacy. In addition, the potassium metabisulfite is believed to be more efficacious at killing microbes at low (acidic) pH and in aqueous conditions, whereas in some embodiments, the potassium metabisulfite is in a solid or dry state, and / or the plastic carriers and compositions of the present disclosure have a neutral pH. Furthermore, as shown in the present disclosure, potassium metabisulfite displays surprisingly effective antimicrobial properties when incorporated in a thermoplastic or thermoplastic elastomer carrier, whereas a similar compound sodium metabisulfite displays very little antimicrobial activity under the same conditions and forms, despite sodium metabisulfite being a more popular and effective antimicrobial agent in other industrial applications.

[0054] Further, incorporation of potassium metabisulfite into plastic carriers also achieves a more sustained release of SO2, unlike the rapid and uncontrolled release of SO2 by sulfur pads. In embodiments, the plastic carrier is a thermoplastic or thermoplastic elastomer carrier. In some embodiments, potassium metabisulfite is incorporated as a masterbatch. In some embodiments, potassium metabisulfite is present both on the surface and in the bulk of the plastic carrier. In some embodiments, potassium metabisulfite is incorporated as a coating.

[0055] The plastic carriers of the disclosure and their antimicrobial properties have broad applications. An exemplary application is to preserve products such as fruits and vegetables in the food industry.Plastic Carriers and Compositions

[0056] In one aspect, the disclosure provides plastic carriers comprising potassium metabisulfite. In some embodiments, such plastic carriers have antimicrobial properties. In some embodiments, such plastic carriers do not comprise an additional antimicrobial additive (other than potassium metabisulfite).

[0057] In some embodiments, the plastic carrier or composition of the disclosure has a pH of from about 6 to about 8. In some embodiments, the plastic carrier or composition has a pH of from about 6.5 to about 7.5. In some embodiments, the plastic carrier or composition has a neutral pH.

[0058] In some embodiments, the plastic carrier emits an effective amount of SO2. The release rate of SO2 may depend on a number of factors including: the concentration, size, shape, and / or distribution of potassium metabisulfite, moisture level, pH, gas permeability and / or thickness of the plastic carrier.

[0059] In some embodiments, the plastic carrier is in the format of a film, a sticker, a fiber, a foam, a disc, a box, a lid, a punnet, or a container. In some embodiments, the plastic carrier is in the format of a film. In some embodiments, the film is manufactured via injection molding or extrusion. In some embodiments, the plastic carrier is in the format of a sticker. In some embodiments, the stick is manufactured by fixing an adhesive material to a plastic film. In some embodiments, the plastic carrier is in the format of a fiber. In some embodiments, the fiber is manufactured via a spinning method. In some embodiments, the plastic carrier is in the format of a foam. In some embodiments, the plastic carrier further comprises an adhesive material on a surface of the plastic carrier. The surface comprising the adhesive material may or may not contain potassium metabisulfite.

[0060] In some embodiments, the plastic carrier comprises only a single layer of plastic material. In some embodiments, the plastic carrier does not comprise a layer of plastic material that does not comprise potassium metabisulfite.

[0061] In some embodiments, the plastic carrier does not comprise sodium metabisulfite, sodium sulfite, and / or sodium bisulfite.

[0062] In some embodiments, the antimicrobial property of the plastic carrier is imparted by potassium metabisulfite alone.

[0063] In some embodiments, the plastic is a food grade plastic.

[0064] In some embodiments, the plastic carrier is gas permeable.

[0065] In some embodiments, the surface of the plastic carrier comprising the potassium metabisulfite has a surface area of at least 0.1 cm2. In some embodiments, the surface of the plastic carrier comprising the potassium metabisulfite has a surface area of at least 0.5 cm2, at least 1 cm2, at least 2 cm2, at least 5 cm2, at least 10 cm2, at least 20 cm2, at least 50 cm2, or at least 100 cm2, including all ranges and subranges therebetween. In some embodiments, the surface of the plastic carrier comprising the potassium metabisulfite has a surface area of between about 0.1 cm2and about 20,000 cm2, e.g., about 0.1 cm2, 0.2 cm2, 0.3 cm2, 0.4 cm2, 0.5 cm2, 0.6 cm2, 0.7 cm2, 0.8 cm2, 0.9 cm2, 1 cm2, 2 cm2, 3 cm2, 4 cm2, 5 cm2, 6 cm2, 7 cm2, 8 cm2, 9 cm2, 10 cm2, 20 cm2, 30 cm2, 40 cm2, 50 cm2, 60 cm2, 70 cm2, 80 cm2, 90 cm2, 100 cm2, 200 cm2, 300 cm2, 400 cm2, 500 cm2, 600 cm2, 700 cm2, 800 cm2, 900 cm2, 1,000 cm2, 5,000 cm2, 10,000 cm2, or 20,000 cm2, including all values and ranges therebetween. In some embodiments, the surface of the plastic carrier comprising the potassium metabisulfite has a surface area of between 0.1 cm2and 0.5 cm2, between 0.2 cm2and 1 cm2, between 0.5 cm2and 2 cm2, between 1 cm2and 5 cm2, between 2 cm2and 10 cm2, between 5 cm2and 20 cm2, between 10 cm2and 50 cm2, between 20 cm2and 100 cm2, between 50 cm2and 200 cm2,between 100 cm2and 500 cm2, between 200 cm2and 1,000 cm2, between 500 cm2and 5,000 cm2, or between 2,000 cm2and 20,000 cm2, including all ranges and subranges therebetween. In some embodiments, the surface of the plastic carrier comprising the potassium metabisulfite has a surface area of no more than 100 cm2, no more than 50 cm2, no more than 20 cm2, no more than 10 cm2, no more than 5 cm2, no more than 2 cm2, or no more than 1 cm2, including all ranges and subranges therebetween.

[0066] In some embodiments, the thickness of the plastic carrier is between about 10 pm and about 10 mm, e.g., about 10 pm, 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, 100 pm, 200 pm, 300 pm, 400 pm, 500 pm, 600 pm, 700 pm, 800 pm, 900 pm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, or 10 mm, including all values and ranges therebetween. In some embodiments, the thickness of the plastic carrier is between 10 pm and 50 pm, between 20 pm and 100 pm, between 50 pm and 200 pm, between 100 pm and 500 pm, between 200 pm and 1 mm, between 500 pm and 2 mm, between 1 mm and 5 mm, or between 2 mm and 10 mm, including all ranges and subranges therebetween. In some embodiments, the thickness of the plastic carrier is between 100 pm and 2 mm. In some embodiments, the thickness of the plastic carrier is between 100 pm and 1.5 mm. In some embodiments, the thickness of the plastic carrier is between 100 pm and 1 mm. In some embodiments, the thickness of the plastic carrier is between 100 pm and 500 pm.

[0067] In some embodiments, the volume of the plastic carrier is between about 0.1 cm3and about 100,000 cm3, e.g., about 0.1 cm3, 0.2 cm3, 0.5 cm3, 1 cm3, 2 cm3, 5 cm3, 10 cm3, 20 cm3, 50 cm3, 100 cm3, 200 cm3, 500 cm3, 1,000 cm3, 2,000 cm3, 5,000 cm3, 10,000 cm3, 20,000 cm3, 50,000 cm3, or 100,000 cm3, including all values and ranges therebetween. In some embodiments, the volume of the plastic carrier is between 0.1 cm3and 10 cm3, between 1 cm3and 100 cm3, between 10 cm3and 1,000 cm3, between 100 cm3and 10,000 cm3, or between 1,000 cm3and 100,000 cm3, including all ranges and subranges therebetween. In some embodiments, the volume of the plastic carrier is between 1 cm3and 100 cm3. The volume here refers to the physical volume of the material forming the plastic carrier. For example, the plastic carrier may be in the form of a plastic container, in which case the volume here refers to the physical space occupied by the container sides and does not include the space of the interior of the container. In some embodiments, the plastic carrier has a surface-to-volume ratio between about 0.1 cmA(-l) and about 500 cmA(-l), e.g., about 0.1 cmA(-l), 0.2 cmA(-l), 0.5 cmA(-l), 1 cmA(-l), 2 cmA(-l), 5 cmA(-l), 10 cmA(-l), 20 cmA(-l), 50 cmA(-l), 100 cmA(-l), 200 cmA(-1), or 500 cmA(-l), including all values and ranges therebetween. In some embodiments, the plastic carrier has a surface-to-volume ratio between 0.1 cmA(-l) and 10 cmA(-l), between 1cm^(-1) and 100 cm^(-1), between 10 cm^(-1) and 1 mm^(-1), between 100 cm^(-1) and 10 mm^(-1), or between 10 m^(-1) and 1,000 m^(-1), including all ranges and subranges therebetween. In some embodiments, the plastic carrier has a surface-to-volume ratio ranging from 10 cm^(-1) to 500 cm^(-1). In some embodiments, the plastic carrier has a surface-to-volume ratio ranging from 100 cm^(-1) to 5,000 cm^(-1).Potassium Metabisulfite

[0068] In some embodiments, potassium metabisulfite confers antimicrobial properties to the plastic carrier of the disclosure. In some embodiments, potassium metabisulfite displays superior antimicrobial properties compared to alternative antimicrobial agents, in terms of compatibility with plastic carrier and / or long-term efficacy (e.g., reducing the likelihood for microbes to develop resistance to the antimicrobial agent). Potassium metabisulfite confers its antimicrobial properties, at least in part, through the release of SO2, especially at the presence of moisture. Descriptions of alternative antimicrobial agents and compositions can be found, for example, in WO 2016 / 207183, WO 2021 / 138144, US 2003 / 089891, WO 2009 / 051594, Foralosso etal., (2014) Food Bioprocess Technol 7:1483-1495, and BR102012029518B1, the content of each of which is incorporated by reference in its entirety.

[0069] In some embodiments, the plastic carrier comprises (i) potassium metabisulfite and (ii) a plastic material. In some embodiments, the plastic carrier comprises about 0.1% (w / w) to about 50% (w / w) potassium metabisulfite, e.g., about 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 25%, 30%, 35%, 40%, 45%, or 50%, (w / w) potassium metabisulfite, including all values and ranges therebetween. In some embodiments, the plastic carrier comprises between about 0.1% (w / w) and about 0.2% (w / w), between about 0.2% (w / w) and about 0.5% (w / w), between about 0.5% (w / w) and about 1% (w / w), between about 1% (w / w) and about 2% (w / w), between about 2% (w / w) and about 5% (w / w), between about 5% (w / w) and about 10% (w / w), between about 10% (w / w) and about 15% (w / w), between about 15% (w / w) and about 20% (w / w), between about 20% (w / w) and about 25% (w / w), between about 25% (w / w) and about 30% (w / w), between about 30% (w / w) and about 40% (w / w), between about 40% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 0.5% (w / w), between about 0.2% (w / w) and about 1% (w / w), between about 0.5% (w / w) and about 2% (w / w), between about 1% (w / w) and about 5% (w / w), between about 2% (w / w) and about 10% (w / w), between about 5% (w / w) and about 15% (w / w), between about 10% (w / w) and about 20% (w / w), between about 15% (w / w) and about 25% (w / w), between about 20% (w / w) and about 30% (w / w), between about25% (w / w) and about 40% (w / w), between about 30% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 1% (w / w), between about 0.2% (w / w) and about 2% (w / w), between about 0.5% (w / w) and about 5% (w / w), between about 1% (w / w) and about 10% (w / w), between about 2% (w / w) and about 15% (w / w), between about 5% (w / w) and about 20% (w / w), between about 10% (w / w) and about 25% (w / w), between about 15% (w / w) and about 30% (w / w), between about 20% (w / w) and about 40% (w / w), between about 25% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 2% (w / w), between about 0.2% (w / w) and about 5% (w / w), between about 0.5% (w / w) and about 10% (w / w), between about 1% (w / w) and about 15% (w / w), between about 2% (w / w) and about 20% (w / w), between about 5% (w / w) and about 25% (w / w), between about 10% (w / w) and about 30% (w / w), between about 15% (w / w) and about 40% (w / w), between about 20% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 5% (w / w), between about 0.2% (w / w) and about 10% (w / w), between about 0.5% (w / w) and about 15% (w / w), between about 1% (w / w) and about 20% (w / w), between about 2% (w / w) and about 25% (w / w), between about 5% (w / w) and about 30% (w / w), between about 10% (w / w) and about 40% (w / w), between about 15% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 10% (w / w), between about 0.2% (w / w) and about 15% (w / w), between about 0.5% (w / w) and about 20% (w / w), between about 1% (w / w) and about 25% (w / w), between about 2% (w / w) and about 30% (w / w), between about 5% (w / w) and about 40% (w / w), between about 10% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 15% (w / w), between about 0.2% (w / w) and about 20% (w / w), between about 0.5% (w / w) and about 25% (w / w), between about 1% (w / w) and about 30% (w / w), between about 2% (w / w) and about 40% (w / w), between about 5% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 20% (w / w), between about 0.2% (w / w) and about 25% (w / w), between about 0.5% (w / w) and about 30% (w / w), between about 1% (w / w) and about 40% (w / w), between about 2% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 25% (w / w), between about 0.2% (w / w) and about 30% (w / w), between about 0.5% (w / w) and about 40% (w / w), between about 1% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 30% (w / w), between about 0.2% (w / w) and about 40% (w / w), between about 0.5% (w / w) and about 50% (w / w), between about 0.1% (w / w) and about 40% (w / w), or between about 0.2% (w / w) and about 50% (w / w), potassium metabisulfite, including all ranges and subranges therebetween. In some embodiments, the plastic carrier comprises between about 1% (w / w) and about 5% (w / w) potassium metabisulfite. In some embodiments, the plastic carrier comprises between about 2% (w / w) and about 10% (w / w) potassium metabisulfite. In some embodiments, the plastic carriercomprises between about 5% (w / w) and about 15% (w / w) potassium metabisulfite. In some embodiments, the plastic carrier comprises between about 15% (w / w) and about 25% (w / w) potassium metabisulfite.

[0070] In some embodiments, at least a portion of the potassium metabisulfite is present on at least one surface of the plastic carrier. In some embodiments, the depth of the surface is about 5-50 pm, about 10-40 pm, about 20-30 pm, or more specifically, about 25 pm, including all ranges and subranges therebetween. In some embodiments, at least about 1% to at least about 90% of the potassium metabisulfite, e.g., at least about 1%, at least about 2%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 50%, at least about 70%, or at least about 90% of the potassium metabisulfite, is present on the surface of the plastic carrier, including all values and ranges therebetween. In some embodiments, between about 1% and about 2%, between about 2% and about 5%, between about 5% and about 10%, between about 10% and about 20%, between about 20% and about 40%, between about 40% and about 60%, between about 60% and about 80%, or between about 80% and about 100%, of the potassium metabisulfite is present on the surface of the plastic carrier, including all ranges and subranges therebetween. In some embodiments, at least a portion, or all of, potassium metabisulfite is incorporated as a coating.

[0071] In some embodiments, at least a portion of the potassium metabisulfite is present in the bulk of the plastic carrier. In some embodiments, at least about 1% to at least about 90% of the potassium metabisulfite, e.g., at least about 1%, at least about 2%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 50%, at least about 70%, or at least about 90%, of the potassium metabisulfite is present in the bulk of the plastic carrier, including all values and ranges therebetween. In some embodiments, between about 1% and about 2%, between about 2% and about 5%, between about 5% and about 10%, between about 10% and about 20%, between about 20% and about 40%, between about 40% and about 60%, between about 60% and about 80%, or between about 80% and about 100%, of the potassium metabisulfite is present in the bulk of the plastic carrier, including all ranges and subranges therebetween. The bulk of the plastic carrier is underneath the surface region of the plastic carrier, and thus excludes the surface region. Thus, a skilled person would understand that, for plastic carriers that comprise a portion of potassium metabisulfite on the surface, the percentage of potassium metabisulfite in the bulk of the plastic carrier is less than 100%.

[0072] In some embodiments, the potassium metabisulfite is in a dry form. In some embodiments, the potassium metabisulfite is in the form of a mini bead, a pellet or a powder. In some embodiments, the potassium metabisulfite is in a powdered form.

[0073] In some embodiments, the potassium metabisulfite is present in the plastic carrier as granules. In some embodiments, the potassium metabisulfite granules have an average size of between about 0.1 pm and about 500 pm, e.g., about 0.1 pm, 0.2 pm, 0.5 pm, 1 pm, 2 pm, 5 pm, 10 pm, 20 pm, 50 pm, 100 pm, 200 pm, or 500 pm, including all values and ranges therebetween. In some embodiments, the granules have an irregular shape, and the size is determined by the longest length of the granule (for example, the longest length of a cube is its body diagonal). In some embodiments, the potassium metabisulfite granules have an average size of between about 0.1 pm and about 0.2 pm, between about 0.2 pm and about 0.5 pm, between about 0.5 pm and about 1 pm, between about 1 pm and about 2 pm, between about 2 pm and about 5 pm, between about 5 pm and about 10 pm, between about 10 pm and about 20 pm, between about 20 pm and about 30 pm, between about 30 pm and about 40 pm, between about 40 pm and about 50 pm, between about 50 pm and about 70 pm, between about 70 pm and about 100 pm, between about 100 pm and about 200 pm, between about 200 pm and about 500 pm, between about 0.1 pm and about 0.5 pm, between about 0.2 pm and about 1 pm, between about 0.5 pm and about 2 pm, between about 1 pm and about 5 pm, between about 2 pm and about 10 pm, between about 5 pm and about 20 pm, between about 10 pm and about 30 pm, between about 20 pm and about 40 pm, between about 30 pm and about 50 pm, between about 40 pm and about 70 pm, between about 50 pm and about 100 pm, between about 70 pm and about 200 pm, between about 100 pm and about 500 pm, between about 0.1 pm and about 1 pm, between about 0.2 pm and about 2 pm, between about 0.5 pm and about 5 pm, between about 1 pm and about 10 pm, between about 2 pm and about 20 pm, between about 5 pm and about 30 pm, between about 10 pm and about 40 pm, between about 20 pm and about 50 pm, between about 30 pm and about 70 pm, between about 40 pm and about 100 pm, between about 50 pm and about 200 pm, between about 70 pm and about 500 pm, between about 0.1 pm and about 2 pm, between about 0.2 pm and about 5 pm, between about 0.5 pm and about 10 pm, between about 1 pm and about 20 pm, between about 2 pm and about 30 pm, between about 5 pm and about 40 pm, between about 10 pm and about 50 pm, between about 20 pm and about 70 pm, between about 30 pm and about 100 pm, between about 40 pm and about 200 pm, between about 50 pm and about 500 pm, between about 0.1 pm and about 5 pm, between about 0.2 pm and about 10 pm, between about 0.5 pm and about 20 pm, between about 1 pm and about 30 pm, between about 2 pm and about 40 pm, between about 5 pm and about 50 pm, between about 10 pm and about 70 pm, between about 20 pm and about 100 pm, between about 30 pm and about 200 pm, between about 40 pm and about 500 pm, between about 0.1 pm and about 10 pm, between about 0.2 pm and about 20 pm, betweenabout 0.5 pm and about 30 pm, between about 1 pm and about 40 pm, between about 2 pm and about 50 pm, between about 5 pm and about 70 pm, between about 10 pm and about 100 pm, between about 20 pm and about 200 pm, between about 30 pm and about 500 pm, between about 0.1 pm and about 20 pm, between about 0.2 pm and about 30 pm, between about 0.5 pm and about 40 pm, between about 1 pm and about 50 pm, between about 2 pm and about 70 pm, between about 5 pm and about 100 pm, between about 10 pm and about 200 pm, between about 20 pm and about 500 pm, between about 0.1 pm and about 30 pm, between about 0.2 pm and about 40 pm, between about 0.5 pm and about 50 pm, between about 1 pm and about 70 pm, between about 2 pm and about 100 pm, between about 5 pm and about 200 pm, between about 10 pm and about 500 pm, between about 0.1 pm and about 40 pm, between about 0.2 pm and about 50 pm, between about 0.5 pm and about 70 pm, between about 1 pm and about 100 pm, between about 2 pm and about 200 pm, between about 5 pm and about 500 pm, between about 0.1 pm and about 50 pm, between about 0.2 pm and about 70 pm, between about 0.5 pm and about 100 pm, between about 1 pm and about 200 pm, between about 2 pm and about 500 pm, between about 0.1 pm and about 70 pm, between about 0.2 pm and about 100 pm, between about 0.5 pm and about 200 pm, between about 1 pm and about 500 pm, between about 0.1 pm and about 100 pm, between about 0.2 pm and about 200 pm, between about 0.5 pm and about 500 pm, between about 0.1 pm and about 200 pm, between about 0.2 pm and about 500 pm, or between about 0.1 pm and about 500 pm, including all ranges and subranges therebetween. In some embodiments, the potassium metabisulfite granules have an average size of no more than 50 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 5 pm and about 50 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 10 pm and about 50 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 20 pm and about 50 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 30 pm and about 50 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 20 pm and about 40 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 10 pm and about 30 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 5 pm and about 25 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 5 pm and about 20 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 5 pm and about 15 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 5 pm and about 10 pm. In some embodiments,the potassium metabisulfite granules have an average size of between about 10 pm and about 25 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 10 pm and about 20 pm. In some embodiments, the potassium metabisulfite granules have an average size of between about 10 pm and about 15 pm. The sizes of the potassium metabisulfite granules can be measured using techniques known in the art — for example, Malvern Laser Diffractometer.

[0074] In some embodiments, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95% of potassium metabisulfite is in direct contact with the plastic material in the composition or the plastic carrier, including all ranges and subranges therebetween. In some embodiments, all or substantially all of potassium metabisulfite is in direct contact with the plastic material in the composition or the plastic carrier.

[0075] Potassium metabisulfite is known to decompose at a temperature of above 150°C. In some embodiments, incorporation into the plastic material or masterbatch of the disclosure significantly increases the decomposition (i.e., onset of degradation) temperature of potassium metabisulfite. In some embodiments, the onset of degradation temperature of potassium metabisulfite in the plastic material or masterbatch is greater than about 150°C, e.g., at least about 160°C, at least about 170°C, at least about 180°C, at least about 190°C, at least about 200°C, at least about 210°C, at least about 220°C, at least about 230°C, at least about 240°C, or at least about 250°C, including all values and ranges therebetween. In some embodiments, the onset of degradation temperature of potassium metabisulfite in the plastic material or masterbatch is between 150°C and 160°C, between 160°C and 170°C, between 170°C and 180°C, between 180°C and 190°C, between 190°C and 200°C, between 200°C and 210°C, between 210°C and 220°C, between 220°C and 230°C, between 230°C and 240°C, between 240°C and 250°C, between 150°C and 170°C, between 160°C and 180°C, between 170°C and 190°C, between 180°C and 200°C, between 190°C and 210°C, between 200°C and 220°C, between 210°C and 230°C, between 220°C and 240°C, between 230°C and 250°C, between 150°C and 180°C, between 160°C and 190°C, between 170°C and 200°C, between 180°C and 210°C, between 190°C and 220°C, between 200°C and 230°C, between 210°C and 240°C, between 220°C and 250°C, between 150°C and 190°C, between 160°C and 200°C, between 170°C and 210°C, between 180°C and 220°C, between 190°C and 230°C, between 200°C and 240°C, between 210°C and 250°C, between 150°C and 200°C, between 160°C and 210°C, between 170°C and 220°C, between 180°C and 230°C, between 190°C and 240°C, between 200°C and 250°C, between 150°C and 210°C, between 160°C and 220°C, between 170°C and 230°C, between 180°C and 240°C, between 190°C and 250°C, between 150°C and 220°C,between 160°C and 230°C, between 170°C and 240°C, between 180°C and 250°C, between 150°C and 230°C, between 160°C and 240°C, between 170°C and 250°C, between 150°C and 240°C, between 160°C and 250°C, or between 150°C and 250°C, including all ranges and subranges therebetween. In some embodiments, the onset of degradation temperature of potassium metabisulfite in the plastic material or masterbatch is between 180°C and 220°C, between 190°C and 220°C, between 200°C and 210°C, or between 200°C and 205°C.

[0076] In some embodiments, all or substantially all of potassium metabisulfite is in direct contact with the plastic material of the plastic carrier or masterbatch. In embodiments, more than about 60%, more than about 70%, more than about 80%, more than about 85%, more than about 90%, more than about 95%, more than about 97%, more than about 98%, more than about 99%, or 100%, of the potassium metabisulfite, including all values and ranges therebetween, is in direct contact with the plastic material of the plastic carrier or masterbatch.

[0077] In some embodiments, no potassium metabisulfite in the plastic carrier or masterbatch is encapsulated in a non-plastic material (which in turn may be embedded in the plastic material). In some embodiments, no potassium metabisulfite in the plastic carrier or masterbatch is encapsulated in a non-polymer material (which in turn may be embedded in the plastic material). In some embodiments, no potassium metabisulfite in the plastic carrier or masterbatch is encapsulated in a metal oxide, silicon dioxide, or other non-plastic materials, for example via a sol-gel process. In some embodiments, less than about 40%, less than about 30%, less than about 20%, less than about 15%, less than about 10%, less than about 5%, less than about 3%, less than about 2%, or less than about 1%, of potassium metabisulfite, including all values and ranges therebetween, in the plastic carrier or masterbatch is encapsulated in a non-plastic material (e.g., metal oxide or silicon dioxide).

[0078] In some embodiments, the disclosure provides the use of a potassium metabisulfite containing composition as a masterbatch for incorporation into a plastic material.

[0079] In some embodiments, the disclosure provides the use of a potassium metabisulfite containing composition as a coating for application to a surface of a plastic material. For example, the plastic carrier may comprise multiple layers, with the first (top) layer being a plastic coating comprising potassium metabisulfite.

[0080] Where the composition is for use as a polymeric binder for coatings, the composition may further include additional components that enable the specified use. Examples include binders, cross-linkers, stabilisers and / or compatibilisers which may be added in any combination with any suitable homopolymer, copolymer or elastomer.

[0081] In some cases, the release of SO2 by potassium metabisulfite further inhibits the darkening or browning of food product (e.g., by inhibiting the enzyme polyphenol oxidase (PPO)).Masterbatch

[0082] In one aspect, the disclosure provides masterbatches that impart antimicrobial properties to a plastic or polymer material when added to such a material.

[0083] A masterbatch, also termed a polymeric concentrate, is a concentrated mixture of one or more additives (e.g., an active component) blended and extruded together in a carrier matrix. In some embodiments, a masterbatch is used to add the additive(s) or active component s) to a final polymer or plastic product. In some embodiments, a masterbatch of the disclosure comprises a concentrated mixture of potassium metabisulfite blended and extruded together in a plastic carrier matrix. In some embodiments, the masterbatch is a homogeneous mixture.

[0084] In some embodiments, after extrusion, the extrudate is cooled, cut and formed into granules, mini beads, pellets or powders depending on its destined application. The carrier matrix may be resin, wax or a polymer (e.g., polyethylene (PE) (e.g., LDPE), polypropylene (PP), or ethylene vinyl acetate (EVA)) that is compatible with the polymer or plastics material into which the masterbatch is added and diluted. The additive in a masterbatch is encapsulated in the carrier material. This encapsulation in many cases reduces or eliminates any dangerous properties of an additive, as well as protects temperature-sensitive additives during the final product manufacturing process. Encapsulation also protects an additive from exposure to humidity, temperature and UV during storage.

[0085] In some embodiments, masterbatches are added or “let down” into a raw polymer or plastics material and are passed through a blending process which feeds into a molding or extruding machine where the final plastic product is made.

[0086] An advantage of imparting particular properties to a polymer by way of a masterbatch, compared to adding one or more compounds per se, is that masterbatches are highly concentrated. This not only saves on raw component bulk and expense but also allows a higher accuracy of dosing of expensive components and, thus, minimal chance of variance during the manufacturing process of the final product. A masterbatch also provides a form that results in consistent dispersal of active in a finished polymer product, as well as having a long shelf life due to being in solid form and being solvent-free. In some embodiments, meltingprocesses are improved because the carrier in a masterbatch is matched with the polymer(s) into which the masterbatch is added and diluted.

[0087] In some embodiments, the antimicrobial masterbatches of the invention exhibits higher thermal stability and / or higher antimicrobial activity compared to alternative antimicrobial masterbatches (e.g., those metal -based systems using the likes of silver, zinc and copper salts, or systems based on organic antimicrobial agents). Additional descriptions of masterbatches can be found, for example, in US 2016 / 0135470, US 2008 / 0306183, US 2017 / 0240720, and US 2003 / 0235605, the content of each of which is incorporated by reference in its entirety.

[0088] In some embodiments, the masterbatch of the disclosure comprises, consists essentially of, or consists of, (i) a plastic material; and (ii) potassium metabisulfite.

[0089] In some embodiments, the masterbatch of the disclosure comprises between about 1% (w / w) and about 90% (w / w) of potassium metabisulfite, e.g., about 1%, 2%, 3%, 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% (w / w) of potassium metabisulfite, including all values and ranges therebetween. In some embodiments, the masterbatch comprises about 1% (w / w), about 2% (w / w), about 5% (w / w), about 10% (w / w), about 15% (w / w), about 20% (w / w), about 25% (w / w), about 30% (w / w), about 35% (w / w), about 40% (w / w), about 45% (w / w), about 50% (w / w), about 60% (w / w), about 70% (w / w), about 80% (w / w), or about 90% (w / w), of potassium metabisulfite, including all ranges and subranges therebetween. In some embodiments, the masterbatch comprises between about 1% (w / w) and about 2% (w / w), between about 2% (w / w) and about 5% (w / w), between about 5% (w / w) and about 10% (w / w), between about 10% (w / w) and about 15% (w / w), between about 15% (w / w) and about 20% (w / w), between about 20% (w / w) and about 25% (w / w), between about 25% (w / w) and about 30% (w / w), between about 30% (w / w) and about 40% (w / w), between about 40% (w / w) and about 50% (w / w), between about 50% (w / w) and about 60% (w / w), between about 60% (w / w) and about 70% (w / w), between about 70% (w / w) and about 80% (w / w), between about 80% (w / w) and about 90% (w / w), between about 1% (w / w) and about 5% (w / w), between about 2% (w / w) and about 10% (w / w), between about 5% (w / w) and about 15% (w / w), between about 10% (w / w) and about 20% (w / w), between about 15% (w / w) and about 25% (w / w), between about 20% (w / w) and about 30% (w / w), between about 25% (w / w) and about 40% (w / w), between about 30% (w / w) and about 50% (w / w), between about 40% (w / w) and about 60% (w / w), between about 50% (w / w) and about 70% (w / w), between about 60% (w / w) and about 80% (w / w), between about 70% (w / w) and about 90% (w / w), between about 1% (w / w) and about 10% (w / w), between about2% (w / w) and about 15% (w / w), between about 5% (w / w) and about 20% (w / w), between about 10% (w / w) and about 25% (w / w), between about 15% (w / w) and about 30% (w / w), between about 20% (w / w) and about 40% (w / w), between about 25% (w / w) and about 50% (w / w), between about 30% (w / w) and about 60% (w / w), between about 40% (w / w) and about 70% (w / w), between about 50% (w / w) and about 80% (w / w), between about 60% (w / w) and about 90% (w / w), between about 1% (w / w) and about 15% (w / w), between about 2% (w / w) and about 20% (w / w), between about 5% (w / w) and about 25% (w / w), between about 10% (w / w) and about 30% (w / w), between about 15% (w / w) and about 40% (w / w), between about 20% (w / w) and about 50% (w / w), between about 25% (w / w) and about 60% (w / w), between about 30% (w / w) and about 70% (w / w), between about 40% (w / w) and about 80% (w / w), between about 50% (w / w) and about 90% (w / w), between about 1% (w / w) and about 20% (w / w), between about 2% (w / w) and about 25% (w / w), between about 5% (w / w) and about 30% (w / w), between about 10% (w / w) and about 40% (w / w), between about 15% (w / w) and about 50% (w / w), between about 20% (w / w) and about 60% (w / w), between about 25% (w / w) and about 70% (w / w), between about 30% (w / w) and about 80% (w / w), between about 40% (w / w) and about 90% (w / w), between about 1% (w / w) and about 25% (w / w), between about 2% (w / w) and about 30% (w / w), between about 5% (w / w) and about 40% (w / w), between about 10% (w / w) and about 50% (w / w), between about 15% (w / w) and about 60% (w / w), between about 20% (w / w) and about 70% (w / w), between about 25% (w / w) and about 80% (w / w), between about 30% (w / w) and about 90% (w / w), between about 1% (w / w) and about 30% (w / w), between about 2% (w / w) and about 40% (w / w), between about 5% (w / w) and about 50% (w / w), between about 10% (w / w) and about 60% (w / w), between about 15% (w / w) and about 70% (w / w), between about 20% (w / w) and about 80% (w / w), between about 25% (w / w) and about 90% (w / w), between about 1% (w / w) and about 40% (w / w), between about 2% (w / w) and about 50% (w / w), between about 5% (w / w) and about 60% (w / w), between about 10% (w / w) and about 70% (w / w), between about 15% (w / w) and about 80% (w / w), between about 20% (w / w) and about 90% (w / w), between about 1% (w / w) and about 50% (w / w), between about 2% (w / w) and about 60% (w / w), between about 5% (w / w) and about 70% (w / w), between about 10% (w / w) and about 80% (w / w), between about 15% (w / w) and about 90% (w / w), between about 1% (w / w) and about 60% (w / w), between about 2% (w / w) and about 70% (w / w), between about 5% (w / w) and about 80% (w / w), between about 10% (w / w) and about 90% (w / w), between about 1% (w / w) and about 70% (w / w), between about 2% (w / w) and about 80% (w / w), between about 5% (w / w) and about 90% (w / w), between about 1% (w / w) and about 80% (w / w), or between about 2% (w / w) and about 90% (w / w),potassium metabisulfite, including all ranges and subranges therebetween. In some embodiments, the masterbatch comprises between about 15% (w / w) and about 30% (w / w) potassium metabisulfite. In some embodiments, the masterbatch comprises between about 20% (w / w) and about 80% (w / w) potassium metabisulfite. In some embodiments, the masterbatch comprises between about 20% (w / w) and about 40% (w / w) potassium metabisulfite. In some embodiments, the masterbatch comprises between about 30% (w / w) and about 50% (w / w) potassium metabisulfite. In some embodiments, the masterbatch comprises between about 40% (w / w) and about 60% (w / w) potassium metabisulfite. In some embodiments, the masterbatch comprises about 30% of potassium metabisulfite.Plastics

[0090] Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be molded, extruded or pressed into solid objects of various shapes. Plastics may be derived from fossil fuel -based chemicals such as natural gas or petroleum, or, as in more recent industrial methods, from renewable materials, including corn and cellulose derivatives.

[0091] In one aspect, the disclosure provides plastic materials that can form plastic carriers with potassium metabisulfite. In some embodiments, the plastic material forming the plastic carrier is a food grade plastic. In some embodiments, the plastic material forms a gas permeable plastic.

[0092] In some embodiments, the plastic is capable of injection molding at a temperature of up to 250°C. In some embodiments, the plastic is capable of injection molding at a temperature of between about 100°C and about 250°C, e.g., about 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, or 250°C, including all values and ranges therebetween. In some embodiments, the plastic is capable of injection molding at a temperature of between 100°C and 125°C, between 125°C and 150°C, between 150°C and 170°C, between 170°C and 190°C, between 190°C and 210°C, between 210°C and 230°C, between 230°C and 250°C, between 100°C and 150°C, between 125°C and 170°C, between 150°C and 190°C, between 170°C and 210°C, between 190°C and 230°C, between 210°C and 250°C, between 100°C and 170°C, between 125°C and 190°C, between 150°C and 210°C, between 170°C and 230°C, between 190°C and 250°C, between 100°C and 190°C, between 125°C and 210°C, between 150°C and 230°C, between 170°C and 250°C, between 100°C and 210°C, between 125°C and 230°C, between 150°C and 250°C, between100°C and 230°C, or between 125 °C and 250°C, including all ranges and subranges therebetween. In some embodiments, the plastic is capable of injection molding at a temperature of at least 150°C. In some embodiments, the plastic is capable of injection molding at a temperature of between 150°C and 250°C.

[0093] In some embodiments, the plastic material comprises a thermoplastic or thermoplastic elastomer. A thermoplastic, or thermo-softening plastic, is a plastic polymer material that softens and becomes pliable or moldable when heated and solidifies on cooling. Once softened, a thermoplastic may be processed using methods such as extrusion, injection molding, thermoforming and blow molding. These types of plastics can be reshaped or remolded numerous times and, once cooled, show no changes in chemical property after being heated and cooled multiple times, making them easily recyclable and reusable.

[0094] In some embodiments, the plastic material comprises a polyolefin, polyester, acrylic or an ester derivative thereof, polyolefin elastomer, thermoplastic elastomer, elastomer, or any combinations thereof. In some embodiments, the plastic material comprises a polyolefin, polyester, or a combination thereof.

[0095] In some embodiments, the plastic material comprises a polyolefin, polyester, polyoxymethylene (POM), polyvinylidene fluoride (PVDF), polymethylmethacrylate (PMMA), polystyrene (PS), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), ethylene-vinyl acetate (EVA), ethylene methyl acrylate (EMA), polyvinyl alcohol (PVA), styrene acrylonitrile resin (SAN), or any combinations thereof.

[0096] In some embodiments, the plastic material comprises a polyolefin. In some embodiments, the polyolefin comprises a polypropylene (PP), polyethylene (PE), or any combinations thereof. In some embodiments, the polyolefin is selected from the group consisting of polypropylene (PP), polyethylene (PE), polymethylpentene (PMP), polybutene-1 (PB-1), ethyl ene-octene copolymer, stereo-block PP, olefin block copolymer, and propylenebutane copolymer.

[0097] In some embodiments, the plastic material comprises polypropylene (PP).

[0098] In some embodiments, the plastic material comprises a polyethylene (PE). In some embodiments, the polyethylene comprises ultra-high molecular weight polyethylene (UHMWPE), high density polyethylene (HDPE), cross-linked high density polyethylene (XLPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), ultra-low density polyethylene (ULDPE), low density polyethylene (LDPE), or any combinations thereof.

[0099] In some embodiments, the plastic material comprises a polyester. In some embodiments, the polyester comprises a lactone-based polymer. In some embodiments, the polyester comprises poly(lactide) (PLA), polycaprolactone (PCL), valeral actone, polyglycolide, pentadecalactone, or any combinations thereof. In some embodiments, the polyester comprises an aromatic thermoplastic polyester,

[0100] In some embodiments, the plastic material comprises polylactic acid (PLA), polycaprolactone (PCL), polyglycolide (PGA), or poly(lactide-co-glycolide) (PLGA). In some embodiments, the plastic carrier is degradable.

[0101] In some embodiments, the plastic material does not comprise polyvinyl chloride (PVC).

[0102] In some embodiments, the plastic material comprises a polyolefin elastomer (POE). In some embodiments, the polyolefin elastomer comprises polyisobutylene (PIB), poly(a-olefin), ethylene propylene rubber (EPR), and ethylene propylene diene monomer (M-class) rubber (EPDM rubber), or any combinations thereof.

[0103] In some embodiments, the plastic material comprises a thermoplastic elastomer (TPE). Thermoplastic elastomers (TPE), sometimes referred to as thermoplastic rubbers (TPR), are a class of copolymers or a physical mix of polymers (usually a plastic and a rubber) that consist of materials with both thermoplastic and elastomeric properties. Thermoplastic elastomers show advantages typical of both rubbery materials and plastic materials. To qualify as a thermoplastic elastomer, a material typically has three characteristics: i) the ability to be stretched to moderate elongations and, upon the removal of stress, return to something close to its original shape; ii) be processable as a melt at an elevated temperature; and (iii) show no significant creep (slow deformation under persistent mechanical stresses). In some embodiments, the thermoplastic elastomer comprises thermoplastic polyurethane (TPU), styrenic block copolymer (TPS), thermoplastic polyolefin elastomer (TPO), thermoplastic vulcanisate (TPV), thermoplastic copolyester (TPC), thermoplastic polyamide (TPA), unclassified thermoplastic elastomer (TPZ), or and combinations thereof.

[0104] In some embodiments, the plastic material comprises an acrylic or an ester derivative thereof. In some embodiments, the acrylic comprises polymethylmethacrylate (PMMA).

[0105] In some embodiments, the plastic material comprises an elastomer. In some embodiments, the elastomer comprises a butadiene-elastomer (BR), styrene-butadiene-elastomer (SBR), polyurethane (PUR), or any combinations thereof.

[0106] In some embodiments, the plastic material comprises a polymer blend or a copolymer. In some embodiments, the polymer blend comprises EVA / PVC. In some embodiments, the co-polymer comprises ABS or SAN.

[0107] In some embodiments, the plastic material comprises a thermoset material. In some embodiments, the thermoset material comprises an epoxy resin, a phenol resin, or a polyester resin.

[0108] Further descriptions of plastic materials can be found, for example, in US 2019 / 0233611, US 2017 / 0066931, US 2020 / 0362137, and US 2019 / 0048188, the content of each of which is incorporated by reference in its entirety.

[0109] In some embodiments, the plastic material constitutes at least about 50% (w / w) of the plastic carrier, e.g., at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 99.9% (w / w), including all values and ranges therebetween. In some embodiments, the plastic carrier comprises between about 50% (w / w) and about 60% (w / w), between about 60% (w / w) and about 70% (w / w), between about 70% (w / w) and about 75% (w / w), between about 75% (w / w) and about 80% (w / w), between about 80% (w / w) and about 85% (w / w), between about 85% (w / w) and about 90% (w / w), between about 90% (w / w) and about 95% (w / w), between about 95% (w / w) and about 98% (w / w), between about 98% (w / w) and about 100% (w / w), between about 50% (w / w) and about 70% (w / w), between about 60% (w / w) and about 75% (w / w), between about 70% (w / w) and about 80% (w / w), between about 75% (w / w) and about 85% (w / w), between about 80% (w / w) and about 90% (w / w), between about 85% (w / w) and about 95% (w / w), between about 90% (w / w) and about 98% (w / w), between about 95% (w / w) and about 100% (w / w), between about 50% (w / w) and about 75% (w / w), between about 60% (w / w) and about 80% (w / w), between about 70% (w / w) and about 85% (w / w), between about 75% (w / w) and about 90% (w / w), between about 80% (w / w) and about 95% (w / w), between about 85% (w / w) and about 98% (w / w), between about 90% (w / w) and about 100% (w / w), between about 50% (w / w) and about 80% (w / w), between about 60% (w / w) and about 85% (w / w), between about 70% (w / w) and about 90% (w / w), between about 75% (w / w) and about 95% (w / w), between about 80% (w / w) and about 98% (w / w), between about 85% (w / w) and about 100% (w / w), between about 50% (w / w) and about 85% (w / w), between about 60% (w / w) and about 90% (w / w), between about 70% (w / w) and about 95% (w / w), between about 75% (w / w) and about 98% (w / w), between about 80% (w / w) and about 100% (w / w), between about 50% (w / w) and about 90% (w / w), between about 60% (w / w) and about 95% (w / w), between about 70% (w / w) and about 98% (w / w), between about 75% (w / w) and about 100% (w / w), between about 50% (w / w) and about 95% (w / w), between about60% (w / w) and about 98% (w / w), between about 70% (w / w) and about 100% (w / w), between about 50% (w / w) and about 98% (w / w), between about 60% (w / w) and about 100% (w / w), or between about 50% (w / w) and about 100% (w / w), plastic material, including all ranges and subranges therebetween. Because of the presence of potassium metabisulfite, the content of the plastic material in the plastic carrier is less than 100% (e.g., may be up to 99.9% (w / w), up to 99.5% (w / w), up to 99% (w / w), or lower).Manufacture of Plastic Carriers

[0110] In one aspect, the disclosure provides methods of manufacturing the plastic carriers of the disclosure.

[0111] In some embodiments, the plastic material and potassium metabisulfite are combined as powders before being heated and extruded into granules, mini beads, pellets or a powder.

[0112] In some embodiments, potassium metabisulfite is incorporated into plastics through masterbatching. In some embodiments, a high weight percent of potassium metabisulfite is initially formed into granules, mini beads, pellets or a powder, which is then diluted by the manufacturer (e.g., during injection molding, extrusion, blow molding, and / or other plastic forming techniques).

[0113] In some embodiments, the method of plastic carrier manufacturing comprises (a) mixing a plastic material and potassium metabisulfite to form a mixture; and (b) subjecting the mixture to a temperature of at least 50 °C, to form the plastic carrier.

[0114] In some embodiments, the method of plastic carrier manufacturing comprises: (a) mixing (i) a masterbatch comprising a first plastic material and potassium metabisulfite and (ii) a second plastic material to form a mixture; and (b) subjecting the mixture to a temperature of at least 50 °C, to form the plastic carrier. In some embodiments, the first plastic material and the second plastic material are the same.

[0115] In some embodiments, the plastic carrier comprises multiple layers, with at least one layer that comprises potassium metabisulfite and at least one layer that does not comprise potassium metabisulfite. In some embodiments, the mixture comprising potassium metabisulfite is co-extruded with other plastic materials without potassium metabisulfite to form the multi-layered plastic carrier.

[0116] In some embodiments, the mixture is a homogeneous mixture.In some embodiments, the mixture at step (b) is subject to a temperature of between about 50 °C and about 250 °C, e.g., about 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C,140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C, including all values and ranges therebetween. In some embodiments, the mixture at step (b) is subject to a temperature of between 50°C and 60°C, between 60°C and 70°C, between 70°C and 80°C, between 80°C and 90°C, between 90°C and 100°C, between 100°C and 110°C, between 110°C and 120°C, between 120°C and 130°C, between 130°C and 140°C, between 140°C and 150°C, between 150°C and 175°C, between 175°C and 200°C, between 200°C and 225°C, between 225°C and 250°C, between 50°C and 70°C, between 60°C and 80°C, between 70°C and 90°C, between 80°C and 100°C, between 90°C and 110°C, between 100°C and 120°C, between 110°C and 130°C, between 120°C and 140°C, between 130°C and 150°C, between 140°C and 175°C, between 150°C and 200°C, between 175°C and 225°C, between 200°C and 250°C, between 50°C and 80°C, between 60°C and 90°C, between 70°C and 100°C, between 80°C and 110°C, between 90°C and 120°C, between 100°C and 130°C, between 110°C and 140°C, between 120°C and 150°C, between 130°C and 175°C, between 140°C and 200°C, between 150°C and 225°C, between 175°C and 250°C, between 50°C and 90°C, between 60°C and 100°C, between 70°C and 110°C, between 80°C and 120°C, between 90°C and 130°C, between 100°C and 140°C, between 110°C and 150°C, between 120°C and 175°C, between 130°C and 200°C, between 140°C and 225°C, between 150°C and 250°C, between 50°C and 100°C, between 60°C and 110°C, between 70°C and 120°C, between 80°C and 130°C, between 90°C and 140°C, between 100°C and 150°C, between 110°C and 175°C, between 120°C and 200°C, between 130°C and 225°C, between 140°C and 250°C, between 50°C and 110°C, between 60°C and 120°C, between 70°C and 130°C, between 80°C and 140°C, between 90°C and 150°C, between 100°C and 175°C, between 110°C and 200°C, between 120°C and 225°C, between 130°C and 250°C, between 50°C and 120°C, between 60°C and 130°C, between 70°C and 140°C, between 80°C and 150°C, between 90°C and 175°C, between 100°C and 200°C, between 110°C and 225°C, between 120°C and 250°C, between 50°C and 130°C, between 60°C and 140°C, between 70°C and 150°C, between 80°C and 175°C, between 90°C and 200°C, between 100°C and 225°C, between 110°C and 250°C, between 50°C and 140°C, between 60°C and 150°C, between 70°C and 175°C, between 80°C and 200°C, between 90°C and 225°C, between 100°C and 250°C, between 50°C and 150°C, between 60°C and 175°C, between 70°C and 200°C, between 80°C and 225°C, between 90°C and 250°C, between 50°C and 175°C, between 60°C and 200°C, between 70°C and 225°C, between 80°C and 250°C, between 50°C and 200°C, between 60°C and 225°C, between 70°C and 250°C, between 50°C and 225°C, between 60°C and 250°C, or between 50°C and 250°C, including all ranges and subranges therebetween

[0117]

[0118] In some embodiments, the mixture at step (b) is subject to a temperature of between about 100 °C and about 250 °C, e.g., about 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, or 250°C, including all values and ranges therebetween. In some embodiments, the mixture at step (b) is subject to a temperature of between 100°C and 125°C, between 125°C and 150°C, between 150°C and 170°C, between 170°C and 190°C, between 190°C and 210°C, between 210°C and 230°C, between 230°C and 250°C, between 100°C and 150°C, between 125°C and 170°C, between 150°C and 190°C, between 170°C and 210°C, between 190°C and 230°C, between 210°C and 250°C, between 100°C and 170°C, between 125°C and 190°C, between 150°C and 210°C, between 170°C and 230°C, between 190°C and 250°C, between 100°C and 190°C, between 125°C and 210°C, between 150°C and 230°C, between 170°C and 250°C, between 100°C and 210°C, between 125°C and 230°C, between 150°C and 250°C, between 100°C and 230°C, or between 125°C and 250°C, including all ranges and subranges therebetween. In some embodiments, the mixture at step (b) is subject to a temperature of no more than 250 °C, no more than 240 °C, no more than 230 °C, no more than 220 °C, no more than 210 °C, no more than 200 °C, or no more than 190 °C. In some embodiments, the mixture at step (b) is subject to a temperature of at least 120 °C, at least 130 °C, at least 140 °C, at least 150 °C, at least 160 °C, at least 170 °C, or at least 180 °C. In some embodiments, the mixture at step (b) is subject to a temperature of at least 150 °C. In some embodiments, the mixture at step (b) is subject to a temperature of between 130 °C and 230 °C. In some embodiments, the mixture at step (b) is subject to a temperature of between 150 °C and 190 °C.

[0119] In some embodiments, the plastic carrier is manufactured by injection molding in step (b). The temperature suitable for injection molding is typically higher than the temperature suitable for an extrusion-based method, because the plastic material is expelled through a smaller opening for injection molding. In some embodiments, the temperature in step (b) provides suitable viscosity for injection molding, which can be determined by a person skilled in the art.

[0120] In some embodiments, the manufacturing method further comprises applying an adhesive material to a surface of the plastic carrier. In some embodiments, the plastic carrier can be attached to other objects (e.g., a container comprising a food product) via the adhesive material.Applications and Containers

[0121] The plastic carriers, compositions, methods, uses, masterbatches and coatings described herein have many applications. Examples of products that benefit from having an antimicrobial profile include: conventional and technical textiles and fabrics, facemasks, high performance non-woven materials such as filters, ventilation systems, surgical gowns, wet wipes, nappies, hygienic pads, wound dressings, food packaging such as plastic bags, vacuum packing, cling and stretch films, rigid and soft containers, bottles and lids for foods and beverages, inserts for packaging and articles including food packaging, household products such as storage boxes (e.g., shoe storage boxes), containers, domestic liquids bottles, waste bins and dustbins, gloves and thin film coatings for various applications including but not limited to hospitals, industrial kitchens, restaurants, products such as shoes, mobile telephones or similar devices, touchscreens, keypads, keyboards, buttons and knobs, handles, screen protectors, banknotes, cup or mug, furniture such as a seat, chair, toilet seat, worktop, upholstery, and high contact materials and appliances include kitchen appliances, doors, taps or faucets, steering wheels, hospital appliances, medical devices, medical components.

[0122] In one aspect, the disclosure provides containers comprising the plastic carrier of the disclosure. In some embodiments, the plastic carrier is located on the exterior of the container. In some embodiments, the plastic carrier is located in the interior of the container. In some embodiments, the plastic carrier is attached to the container via an adhesive material. In some embodiments, the plastic carrier is the container (e.g., shaped as a container).

[0123] In some embodiments, the container is a sealed container. In some embodiments, the container has undergone modified atmosphere packaging.

[0124] In some embodiments, the container comprises a food product. In such embodiments, the plastic carrier may be attached to the interior roof of the container.

[0125] In some embodiments, the ratio of (i) the exposed surface area of the plastic carrier comprising potassium metabisulfite to (ii) the volume of the interior of the container is between about 0.00001 cmA(-l) and about 100 cmA(-l), e.g., about 0.00001 cmA(-l), 0.00003 cmA(-l), 0.0001 cmA(-l), 0.0003 cmA(-l), 0.001 cmA(-l), 0.003 cmA(-l), 0.01 cmA(-l), 0.03 cmA(-l), 0.1 cmA(-l), 0.3 cmA(-l), 1 cmA(-l), 3 cmA(-l), 10 cmA(-l), 30 cmA(-l), or 100 cmA(-l), including all values and ranges therebetween. In some embodiments, the ratio of (i) the exposed surface area of the plastic carrier comprising potassium metabisulfite to (ii) the volume of the interior of the container is between 0.00001 cmA(-l) and 0.0001 cmA(-l), between 0.0001 cmA(-l) and 0.001 cmA(-l), between 0.001 cmA(-l) and 0.01 cmA(-l), between 0.01 cmA(-l) and 0.1 cmA(-l), between 0.1 cmA(-l) and 1 cmA(-l), between 1 cmA(-l) and 10 cmA(-l),between 10 cmA(-l) and 100 cmA(-l), between 0.00001 cmA(-l) and 0.001 cmA(-l), between 0.0001 cmA(-l) and 0.01 cmA(-l), between 0.001 cmA(-l) and 0.1 cmA(-l), between 0.01 cmA(-1) and 1 cmA(-l), between 0.1 cmA(-l) and 10 cmA(-l), between 1 cmA(-l) and 100 cmA(-l), between 0.00001 cmA(-l) and 0.01 cmA(-l), between 0.0001 cmA(-l) and 0.1 cmA(-l), between 0.001 cmA(-l) and 1 cmA(-l), between 0.01 cmA(-l) and 10 cmA(-l), between 0.1 cmA(-l) and 100 cmA(-l), between 0.00001 cmA(-l) and 0.1 cmA(-l), between 0.0001 cmA(-l) and 1 cmA(-1), between 0.001 cmA(-l) and 10cmA(-l), between 0.01 cmA(-l) and 100 cmA(-l), between 0.00001 cmA(-l) and 1 cmA(-l), between 0.0001 cmA(-l) and 10 cmA(-l), between 0.001 cmA(-1) and 100 cmA(-l), between 0.00001 cmA(-l) and 10 cmA(-l), or between 0.0001 cmA(-l) and 100 cmA(-l), including all ranges and subranges therebetween.

[0126] In one aspect, the disclosure provides a method of controlling or killing a microbe on a product. In some embodiments, the method comprises contacting the plastic carrier of the disclosure with the product. In some embodiments, the method comprises placing the plastic carrier of the disclosure in proximity to the product. In some embodiments, the product is a non-food product. In some embodiments, the product is a food product.

[0127] In some embodiments, the plastic carrier is within about 100 cm to the nearest surface of the product, e.g., within about 100 cm, 70 cm, 50cm, 40 cm, 30 cm, 20 cm, 15 cm, 10 cm, 5 cm, 3 cm, 2 cm, 1 cm, 0.5 cm, or 0.2 cm, including all values and ranges therebetween. In some embodiments, the plastic carrier is between about 0.1 cm and about 0.2 cm, between about 0.2 cm and about 0.5 cm, between about 0.5 cm and about 1 cm, between about 1 cm and about 2 cm, between about 2 cm and about 5 cm, between about 5 cm and about 10 cm, between about 10 cm and about 15 cm, between about 15 cm and about 20 cm, between about 20 cm and about 30 cm, between about 30 cm and about 40 cm, between about 40 cm and about 50 cm, between about 50 cm and about 70 cm, between about 70 cm and about 100 cm, between about 0.1 cm and about 0.5 cm, between about 0.2 cm and about 1 cm, between about 0.5 cm and about 2 cm, between about 1 cm and about 5 cm, between about 2 cm and about 10 cm, between about 5 cm and about 15 cm, between about 10 cm and about 20 cm, between about 15 cm and about 30 cm, between about 20 cm and about 40 cm, between about 30 cm and about 50 cm, between about 40 cm and about 70 cm, between about 50 cm and about 100 cm, between about 0.1 cm and about 1 cm, between about 0.2 cm and about 2 cm, between about 0.5 cm and about 5 cm, between about 1 cm and about 10 cm, between about 2 cm and about 15 cm, between about 5 cm and about 20 cm, between about 10 cm and about 30 cm, between about 15 cm and about 40 cm, between about 20 cm and about 50 cm, between about 30 cm and about 70 cm, between about 40 cm and about 100 cm, between about 0.1 cm andabout 2 cm, between about 0.2 cm and about 5 cm, between about 0.5 cm and about 10 cm, between about 1 cm and about 15 cm, between about 2 cm and about 20 cm, between about 5 cm and about 30 cm, between about 10 cm and about 40 cm, between about 15 cm and about 50 cm, between about 20 cm and about 70 cm, between about 30 cm and about 100 cm, between about 0.1 cm and about 5 cm, between about 0.2 cm and about 10 cm, between about 0.5 cm and about 15 cm, between about 1 cm and about 20 cm, between about 2 cm and about 30 cm, between about 5 cm and about 40 cm, between about 10 cm and about 50 cm, between about 15 cm and about 70 cm, between about 20 cm and about 100 cm, between about 0.1 cm and about 10 cm, between about 0.2 cm and about 15 cm, between about 0.5 cm and about 20 cm, between about 1 cm and about 30 cm, between about 2 cm and about 40 cm, between about 5 cm and about 50 cm, between about 10 cm and about 70 cm, between about 15 cm and about 100 cm, between about 0.1 cm and about 15 cm, between about 0.2 cm and about 20 cm, between about 0.5 cm and about 30 cm, between about 1 cm and about 40 cm, between about 2 cm and about 50 cm, between about 5 cm and about 70 cm, between about 10 cm and about 100 cm, between about 0.1 cm and about 20 cm, between about 0.2 cm and about 30 cm, between about 0.5 cm and about 40 cm, between about 1 cm and about 50 cm, between about 2 cm and about 70 cm, between about 5 cm and about 100 cm, between about 0.1 cm and about 30 cm, between about 0.2 cm and about 40 cm, between about 0.5 cm and about 50 cm, between about 1 cm and about 70 cm, between about 2 cm and about 100 cm, between about 0.1 cm and about 40 cm, between about 0.2 cm and about 50 cm, between about 0.5 cm and about 70 cm, between about 1 cm and about 100 cm, between about 0.1 cm and about 50 cm, between about 0.2 cm and about 70 cm, between about 0.5 cm and about 100 cm, between about 0.1 cm and about 70 cm, between about 0.2 cm and about 100 cm, or between about 0.1 cm and about 100 cm, to the product, including all ranges and subranges therebetween.

[0128] In some embodiments, the food product is a dry and / or non-fatty food product. In some embodiments, the food product is a fruit or vegetable. In some embodiments, the food product is a fresh, uncut fruit or vegetable. In some embodiments, the food product is a fresh, cut (or shredded) fruit or vegetable. In some embodiments, the fruit is selected from strawberry, blueberry, raspberry, and grape. In some embodiments, the fruit is an uncut and unpeeled fruit. In some embodiments, the fruit is a packaged fresh fruit, ready-to-eat fruit slice, or loose fruit. In some embodiments, the food product is lettuce, salad, mushrooms, milk, cheese, yogurt, sauce, or condiment. In some embodiments, the cheese is a pre-shredded cheese. In some embodiments, the cheese is cheddar or mozzarella. In some embodiments, the food product is a ready-to-eat meal. In some embodiments, the ready-to-eat meal is a pizza, lasagna, Chinesefood, sandwich, pasta, curry, or soup. In some embodiments, the food product is a frozen fruit or vegetable. In some embodiments, the food product is a dried fruit or vegetable. In some embodiments, the food product is a canned or bottled fruit or vegetable. In some embodiments, the food product is a fruit or vegetable preparation excluding compote. In some embodiments, the food product is a fruit or vegetable in vinegar oil or brine. In some embodiments, the food product is a fruit or vegetable spread. In some embodiments, the food product is a jam, jelly or marmalade. In some embodiments, the food product is a processed potato product, processed nut, potato-based snack, cereal-based snack, flour-based snack, starch-based snack. In some embodiments, the food product is whole, broken or flaked grain. In some embodiments, the food product is a food decoration, coating, or filling. In some embodiments, the food product is a confectionery (e.g., breath freshening microsweet). In some embodiments, the food product is starch, fine bakery ware, meat, unprocessed mollusca or crustacean, processed fish or fisheries product, sugar, syrup, herb, spice, mustard, or a protein product. In some embodiments, the food product is vinegar, diluted acetic acid, fruit juice, flavored drink, beer, malt beverage, wine, cider, perry, fruit wine, made wine, mead, spirit drinks, aromatized wine, aromatized wine-based drink, aromatized wine-product cocktail, or other alcoholic beverages (e.g., mixtures of alcoholic beverages with non-alcoholic beverages, alcoholic beverages with alcoholic strength by volume less than 15%).Antimicrobial Properties and Extension of Shelf Life

[0129] In some embodiments, the plastic carrier of the disclosure has antimicrobial properties. In some embodiments, the antimicrobial properties are imparted, at least in part, by the potassium metabisulfite in the plastic carrier. In some embodiments, the plastic carrier is capable of extending shelflife of another material or product (e.g., a food product).

[0130] In some embodiments, the plastic carrier or container of the disclosure extends shelflife of a food product by at least about 3 days, e.g., about 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 days, including all values and ranges therebetween compared to a control plastic carrier or container that does not comprise potassium metabisulfite. In some embodiments, the temperature of the shelflife measurement is set at 4 °C, 20 °C, 25 °C, or 30 °C, preferably 20 °C. In some embodiments, the temperature of the shelf life measurement is set at 20 °C. In some embodiments, the plastic carrier or container of the disclosure extends shelflife of a food product by 3-5 days, 5-7 days, 7-9 days, 9-12 days, 12-15 days, 15-20 days, 20-30 days, 30-40 days, 40-50 days, 3-7 days, 5-9 days, 7-12 days, 9-15 days, 12-20 days, 15-30 days, 20-40 days, 30-50 days, 3-9 days, 5-12 days, 7-15 days, 9-20 days, 12-30 days, 15-40 days, 20-50 days, 3-12 days, 5-15 days, 7-20 days, 9-30 days, 12-40 days, 15-50 days, 3-15 days, 5-20 days, 7-30 days, 9-40 days, 12-50 days, 3-20 days, 5-30 days, 7-40 days, 9-50 days, 3-30 days, 5-40 days, 7-50 days, 3-40 days, 5-50 days, or 3-50 days, including all ranges and subranges therebetween (e.g., when measured at 20 °C), compared to a control plastic carrier or container that does not comprise potassium metabisulfite.

[0131] In some embodiments, the food product is a dry and / or non-fatty food product. In some embodiments, the food product is a fruit or vegetable. In some embodiments, the food product is a fruit selected from strawberry, blueberry, raspberry, and grape. In some embodiments, the fruit is an uncut and unpeeled fruit.

[0132] In some embodiments, the storage of food in the presence of the plastic carrier or container does not result in significant food migration of potassium metabisulfite. In some embodiments, food migration of potassium metabisulfite is less than about 10 mg / kg, e.g., less than about 10 mg / kg, 5 mg / kg, 2 mg / kg, 1 mg / kg, 0.5 mg / kg, 0.2 mg / kg, 0.1 mg / kg, 0.05 mg / kg, 0.02 mg / kg, 0.01 mg / kg, 0.005 mg / kg, 0.002 mg / kg, 0.001 mg / kg, 0.0005 mg / kg, 0.0002 mg / kg, 0.0001 mg / kg, 0.00005 mg / kg, 0.00002 mg / kg, 0.00001 mg / kg, including all values and ranges therebetween, as measured using TES-AC-812, a contact time of 10 days, and temperature of 40 °C. In some embodiments, food migration of potassium metabisulfite is less than 0.1 mg / kg, less than 0.01 mg / kg, less than 0.001 mg / kg, less than 0.0001 mg / kg, or less than 0.00001 mg / kg, as measured using TES-AC-812, a contact time of 10 days, and temperature of 40 °C. In some embodiments, food migration of potassium metabisulfite is between 0.00001 mg / kg and 0.0001 mg / kg, between 0.0001 mg / kg and 0.001 mg / kg, between 0.001 mg / kg and 0.01 mg / kg, between 0.01 mg / kg and 0.1 mg / kg, or between 0.1 mg / kg and 1 mg / kg, including all ranges and subranges therebetween, as measured using TES-AC-812, a contact time of 10 days, and temperature of 40 °C. In some embodiments, the food is an uncut and unpeeled fruit in the potassium metabisulfite food migration assay.

[0133] In some embodiments, the antimicrobial property comprises antibacterial property. In some embodiments, the antimicrobial property comprises inhibiting or preventing growth of a bacterium. In some embodiments, the antimicrobial property comprises killing a bacterium. In some embodiments, the plastic carrier kills at least about 90%, at least about 95%, or at least about 99% of the bacterium within 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, or 60 minutes, including all ranges and subranges in between, after the plastic carrier is placed in proximity to, or in contact with, the bacterium.In some embodiments, the plastic carrier kills at least about 90%, at least about 95%, or at least about 99% of the bacterium within 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, or 60 hours, including all ranges and subranges in between, after the plastic carrier is placed in proximity to, or in contact with, the bacterium. In some embodiments, the plastic carrier kills at least about 90% of the bacterium within about 1-24 hours after the plastic carrier is placed in proximity to, or in contact with, the bacterium. In some embodiments, the plastic carrier kills at least about 95% of the bacterium within about 1- 24 hours after the plastic carrier is placed in proximity to, or in contact with, the bacterium. In some embodiments, the plastic carrier kills at least about 99% of the bacterium within about 1- 24 hours after the plastic carrier is placed in proximity to, or in contact with, the bacterium. In some embodiments, the plastic carrier kills at least about 99% of the bacterium within about 1 hour after the plastic carrier is placed in proximity to, or in contact with, the bacterium. In some embodiments, the plastic carrier kills at least about 99% of the bacterium within about 24 hour after the plastic carrier is placed in proximity to, or in contact with, the bacterium.

[0134] In some embodiments, the plastic carrier achieves at least a 1 log, 2 log, 3 log, 4 log, 5 log, or 6 log reduction of the number of bacteria within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 1 log reduction of the number of bacteria within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 2 log reduction of the number of bacteria within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 3 log reduction of the number of bacteria within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 4 log reduction of the number of bacteria within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 5 log reduction of the number of bacteria within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 6 log reduction of the number of bacteria within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours.

[0135] In some embodiments, the bacterium is selected from the group consisting of Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Enterococcus faecium, Enterococcus faecalis, Enterococcus faecalis Vancomycin resistant, Listeria monocytogenes, Listeria innocua, Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Legionella pneumophila, Acinetobacter baumannii, Klebsiella pneumoniae, Corynebacterium Xerosis, Salmonella enterica, Pseudomonas aeruginosa, and anycombinations thereof. In some embodiments, the bacterium is selected from the group consisting of Acinetobacter baumannii, Actinomyces israelii, Agrobacterium radiobacter, Agrobacterium tumefaciens, Anaplasma phagocytophilum, Azorhizobium caulinodans, Azotobacter vinelandii, Bacillus anthracis, Bacillus brevis, Bacillus cereus, Bacillus fusiformis, Bacillus licheniformis, Bacillus megaterium, Bacillus mycoides, Bacillus subtilis, Bacillus thuringiensis, Bacteroides fragilis, Bacteroides gingivalis, Bacteroides melaninogenicus, Bartonella henselae, Bartonella quintana, Bordetella bronchiseptica, Bordetella pertussis, Brucella abortus, Brucella melitensis, Brucella suis, Burkholderia mallei, Burkholderia pseudomallei, Burkholderia cepacia, Campylobacter coli, Campylobacter fetus, Campylobacter jejuni, Campylobacter pylori, Chlamydophila pneumoniae, Chlamydophila psittaci, Clostridium botulinum, Clostridium difficile, Clostridium perfringens, Clostridium tetani, Corynebacterium diphtherias, Corynebacterium fusiforme, Coxiella burnetii, Ehrlichia chaffeensis, Enterobacter cloacae, Enterococcus avium, Enterococcus durans, Enterococcus faecalis, Enterococcus faecium, Enterococcus galllinarum, Enterococcus maloratus, Francisella tularensis, Fusobacterium nucleatum, Geobacillus strearothermophilus, Haemophilus influenzae, Haemophilus parainfluenzae, Haemophilus pertussis, Helicobacter pylori, Klebsiella pneumoniae, Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus casei, Lactococcus lactis, Legionella pneumophila, Listeria monocytogenes, Methanobacterium extroquens, Microbacterium multiforme, Micrococcus luteus, Moraxella catarrhalis, Mycobacterium avium, Mycobacterium bovis, Mycobacterium intracellular e, Mycobacterium leprae, Mycobacterium lepraemurium, Mycobacterium phlei, Mycobacterium smegmatis, Mycobacterium tuberculosis, Mycoplasma fermentans, Mycoplasma hominis, Mycoplasma pneumoniae, Neisseria meningitidis, Pasteurella multocida, Pasteurella tularensis, Peptostreptococcus, Porphyromonas gingivalis, Prevotella melaninogenica, Pseudomonas aeruginosa, Rhizobium radiobacter, Rickettsia psittaci, Rochalimaea henselae, Rothia dentocariosa, Salmonella enteritidis, Salmonella typhi, Salmonella typhimurium, Serratia marcescens, Shigella dysenteriae, Spirillum volutans, Stenotrophomonas maltophilia, Streptococcus agalactiae, Streptococcus bovis, Streptococcus cricetus, Streptococcus ferus, Streptococcus gallinarum, Streptococcus mitis, Streptococcus mutans, Streptococcus oralis, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus rattus, Streptococcus salivarius, Streptococcus sanguinis, Streptococcus sobrinus, Treponema pallidum, Treponema denticola, Vibrio cholerae, Vibrio comma, Vibrio parahaemolyticus, Vibrio vulnificus, Viridans streptococci, Yersinia enter ocolitica, Yersinia pestis, Yersinia pseudotuberculosis,and any combinations thereof. In some embodiments, the bacterium is Staphylococcus aureus (S. aureus) and / or Escherichia coli (E. coli).

[0136] In some embodiments, the antimicrobial property comprises antifungal property. In some embodiments, the antimicrobial property comprises inhibiting or preventing growth of a fungus. In some embodiments, the antimicrobial property comprises killing a fungus. In some embodiments, the plastic carrier kills at least about 90%, at least about 95%, or at least about 99% of the fungus within 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, or 60 minutes, including all ranges and subranges in between, after the plastic carrier is placed in proximity to, or in contact with, the fungus. In some embodiments, the plastic carrier kills at least about 90%, at least about 95%, or at least about 99% of the fungus within 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, or 60 hours, including all ranges and subranges in between, after the plastic carrier is placed in proximity to, or in contact with, the fungus. In some embodiments, the plastic carrier kills at least about 90% of the fungus within about 1-24 hours after the plastic carrier is placed in proximity to, or in contact with, the fungus. In some embodiments, the plastic carrier kills at least about 95% of the fungus within about 1-24 hours after the plastic carrier is placed in proximity to, or in contact with, the fungus. In some embodiments, the plastic carrier kills at least about 99% of the fungus within about 1-24 hours after the plastic carrier is placed in proximity to, or in contact with, the fungus. In some embodiments, the plastic carrier kills at least about 99% of the fungus within about 1 hour after the plastic carrier is placed in proximity to, or in contact with, the fungus. In some embodiments, the plastic carrier kills at least about 99% of the fungus within about 24 hours after the plastic carrier is placed in proximity to, or in contact with, the fungus.

[0137] In some embodiments, the plastic carrier achieves at least a 1 log, 2 log, 3 log, 4 log, 5 log, or 6 log reduction of the number of fungi within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 1 log reduction of the number of fungi within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 2 log reduction of the number of fungi within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 3 log reduction of the number of fungi within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 4 log reduction of the number of fungi within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 5 log reduction of the number of fungi within 1, 5, 10, 20, or 30 minutes, orwithin 1, 2, 4, 6, 12, or 24 hours. In some embodiments, the plastic carrier achieves at least a 6 log reduction of the number of fungi within 1, 5, 10, 20, or 30 minutes, or within 1, 2, 4, 6, 12, or 24 hours.

[0138] In some embodiments, the fungus is an Agaricus species, Amanita species, Armillaria species, Aspergillus species, Boletus species, Caloplaca species, Candida species, Cladonia species, Coprinellus species, Coprinopsis species, Cortinarius species, Cyathus species, Deadly fungus species, Entoloma species, Fusarium species, Gymnopilus species, Gymnopus species, Hebeloma species, Hygrocybe species, Hygrophorus species, Inocybe species, Lactarius species, Lactifluus species, Lecanora species, Lepiota species, Leucoagaricus species, Lichen species of Montana, Leccinum species, Marasmius species, Pleurotus species, Mycosphaerella species, Panaeolus species, Penicillium species, Peniophora species, Pertusaria species, Phaeocollybia species, Pholiota species, Pholiotina species, Pluteus species, Poisonous fungus species, Psathyrella species, Psilocybe species, Psilocybin mushroom species, Puccinia species, Russula species, Scleroderma species, Serpula species, Trametes species, Tricholoma species, Tuber species, Tulostoma species, or any combinations thereof. In some embodiments, the fungus comprises a yeast — a nonlimiting example is Candida albicans (C albicans). In some embodiments, the fungus comprises a mold — a non-limiting example is Aspergillus brasiliensis (A. brasiliensis). In some embodiments, the fungus comprises C. albicans and / or brasiliensis.

[0139] In some embodiments, the antimicrobial property comprises antiviral property. In some embodiments, the antimicrobial property comprises inhibiting or preventing growth of a virus. In some embodiments, the antimicrobial property comprises killing a virus.

[0140] Further descriptions of the microorganisms (e.g., pathogenic microorganisms such as bacteria, viruses, and / or fungi) can be found, for example, in US 2018 / 0243333 and US2019 / 0119728, the content of each of which is incorporated by reference in its entirety.

[0141] Acid is usually used as an accelerant in sulfur pads. The present invention, may in some embodiments, also be free of (i.e. not comprise or use) accelerating agents.

[0142] Release rates may also be referred to as emission rates, with reference to the SO2. Without being bound by theory, the release rate is thought to be linear over time, so for example the total SO2 released after 2 days would be expected to be twice that released after 1 day. This may change towards the end of the SO2 release profile as the SO2 is used up. Increasing the temperature of the carrier or its environment will affect the release rate, so it is expected that the release rate will be lower at lower temperatures, compared to higher temperatures. So the release rate of SO2 from a carrier in a refrigerated product would be expected to belower than in the same product at room temperature. The release rate can therefore be controlled by changing the environmental temperature of the carrier. The same applies to the food migration of the released SO2. These can be tested using known techniques standard ways. The release of Sulfur Dioxide is passive. The reaction increases with higher temperature (conversion is rapid at 190C but at Room Temperature it is slow and controlled) LDPE is a good moisture barrier and hence controls the environment. It is also permeable to sulfur dioxide gas. Therefore, the release rate may be controlled thermodynamically and / or through controlling the environment around the salt.

[0143] Example 4 shows that the release rate of SO2 is between 0.6ppm (lower detectable limit) and 10.25ppm as an current upper limit (beyond which the food needs to be labelled as containing sulphites) is possible. In some embodiments, the release rate of SO2 is between approx. 0.6ppm (lower detectable limit) and approx. 10.25ppm.

[0144] In some embodiments, the release rate of SO2 is between about 0.6 ppm and about 10 ppm, between about 0.6 ppm and about 9 ppm, between about 0.6 ppm and about 8 ppm, between about 0.6 ppm and about 7 ppm, between about 0.6 ppm and about 6 ppm, or between about 0.6 ppm and about 5 ppm. In some embodiments, the release rate of SO2 is between about 1 ppm and about 10 ppm, between about 2 ppm and about 10 ppm, between about 3 ppm and about 10 ppm, or between about 4 ppm and about 10 ppm. In some embodiments, the release rate of SO2 is between about 1 ppm and about 8 ppm, between about 2 ppm and about 7 ppm, or between about 3 ppm and about 6 ppm.

[0145] In some embodiments, the release rate of SO2 is maintained at a substantially constant level over a period of at least 1 day, at least 3 days, at least 7 days, at least 14 days, or at least 21 days. In some embodiments, the release rate of SO2 varies by no more than 50%, no more than 30%, no more than 20%, or no more than 10% over the period.

[0146] In some embodiments, the release rate of SO2 is measured under standard conditions of 20°C and 50% relative humidity. In some embodiments, the release rate of SO2 is measured under refrigerated conditions of 4°C. In some embodiments, the release rate of SO2 is measured at elevated temperatures of 30°C or 40°C to simulate accelerated storage conditions.

[0147] In some embodiments, the release rate of SO2 is controlled by adjusting the concentration of potassium metabisulfite in the plastic carrier. In some embodiments, the release rate of SO2 is controlled by adjusting the surface area to volume ratio of the plastic carrier. In some embodiments, the release rate of SO2 is controlled by adjusting the thicknessof the plastic carrier. In some embodiments, the release rate of SO2 is controlled by adjusting the gas permeability of the plastic material.

[0148] In some embodiments, the release rate of SO2 is sufficient to achieve antimicrobial efficacy while remaining below regulatory labeling thresholds for sulfites in food products. In some embodiments, the release rate of SO2 provides a sustained antimicrobial effect without causing sulfur burns or off-flavors in food products.

[0149] In some embodiments, the plastic carrier is designed to provide an initial burst release of SO2 followed by a sustained release phase. In some embodiments, the plastic carrier provides a delayed release of SO2, beginning after an initial lag period of 1-24 hours. In some embodiments, the plastic carrier provides a pulsed release pattern of SO2 in response to environmental triggers such as moisture or temperature changes.

[0150] By temperature, it is anticipated to double the release rate of SO2 every 20 degrees C.

[0151] In terms of release rates, a 4cm x 4cm sticker emits between 0.9 to 25 mg of SO2 in 12 days (i.e. over 12 days in total) at 20C and this is expected to be roughly double at 40C. The rate is expected to be linear.

[0152] In some embodiments, carriers with different dimensions provide proportionally scaled SO2 emission rates. In some embodiments, a 2cm x 2cm carrier emits between about 0.2 mg to about 6.3 mg of SO2 over 12 days at 20°C. In some embodiments, a 3cm x 3cm carrier emits between about 0.5 mg to about 14.1 mg of SO2 over 12 days at 20°C. In some embodiments, a 5cm x 5cm carrier emits between about 1.4 mg to about 39.1 mg of SO2 over 12 days at 20°C. In some embodiments, a 6cm x 6cm carrier emits between about 2.0 mg to about 56.3 mg of SO2 over 12 days at 20°C.

[0153] In some embodiments, rectangular carriers with equivalent surface areas provide similar SO2 emission profiles. In some embodiments, a 2cm x 8cm carrier emits between about 0.9 mg to about 25 mg of SO2 over 12 days at 20°C. In some embodiments, a 3cm x 5.3cm carrier emits between about 0.9 mg to about 25 mg of SO2 over 12 days at 20°C. In some embodiments, a 1cm x 16cm carrier emits between about 0.9 mg to about 25 mg of SO2 over 12 days at 20°C.

[0154] In some embodiments, circular carriers with equivalent surface areas provide comparable SO2 emission characteristics. In some embodiments, a circular carrier with a diameter of about 4.5 cm (providing approximately 16 cm2surface area) emits between about 0.9 mg to about 25 mg of SO2 over 12 days at 20°C. In some embodiments, a circular carrierwith a diameter of about 3.2 cm (providing approximately 8 cm2surface area) emits between about 0.45 mg to about 12.5 mg of SO2 over 12 days at 20°C.

[0155] In some embodiments, the SO2 emission rate varies with temperature according to Arrhenius kinetics. In some embodiments, the emission rate at 4°C is between about 0.3 mg to about 8.3 mg over 12 days. In some embodiments, the emission rate at 30°C is between about 1.4 mg to about 37.5 mg over 12 days. In some embodiments, the emission rate at 50°C is between about 2.7 mg to about 75 mg over 12 days.

[0156] In some embodiments, the SO2 emission follows different kinetic profiles. In some embodiments, the emission rate follows zero-order kinetics, providing constant daily emission rates. In some embodiments, the emission rate follows first-order kinetics, with higher initial emission rates that decrease over time. In some embodiments, the emission rate follows a biphasic profile with an initial burst phase followed by a sustained release phase.

[0157] In some embodiments, carriers with variable thickness provide different emission profiles. In some embodiments, carriers with thickness of 75 microns emit between about 0.45 mg to about 12.5 mg of SO2 over 12 days at 20°C. In some embodiments, carriers with thickness of 300 microns emit between about 1.8 mg to about 50 mg of SO2 over 12 days at 20°C. In some embodiments, carriers with thickness of 500 microns emit between about 3.0 mg to about 83 mg of SO2 over 12 days at 20°C.

[0158] In some embodiments, multiple smaller carriers are used to achieve equivalent total SO2 emission. In some embodiments, four 2cm x 2cm carriers collectively emit between about 0.9 mg to about 25 mg of SO2 over 12 days at 20°C. In some embodiments, two 2cm x 4cm carriers collectively emit between about 0.9 mg to about 25 mg of SO2 over 12 days at 20°C.

[0159] In some embodiments, the SO2 emission is measured over different time periods while maintaining proportional characteristics. In some embodiments, the carrier emits between about 0.6 mg to about 16.7 mg of SO2 over 8 days at 20°C. In some embodiments, the carrier emits between about 1.35 mg to about 37.5 mg of SO2 over 18 days at 20°C. In some embodiments, the carrier emits between about 1.8 mg to about 50 mg of SO2 over 24 days at 20°C.

[0160] In some embodiments, carriers with perforations or surface texturing provide modified emission profiles. In some embodiments, carriers with micro-perforations emit between about 1.4 mg to about 37.5 mg of SO2 over 12 days at 20°C due to increased surface area. In some embodiments, carriers with embossed surfaces emit between about 1.1 mg to about 30 mg of SO2 over 12 days at 20°C.

[0161] Therefore, in some embodiments, the release rate is within this range (when measured under comparable conditions (over 12 days in total compared to a carrier of approx..4cmx4cm (approx. 16cm2) at 20C. In some embodiments, the thickness of the carrier of approx. 4cmx4cm (approx. 16cm2) is as descried herein, in particular 150 microns (+ / - 10% or 15%).

[0162] In some embodiments, the release rate of SO2 is between about 0.075 mg and about 2.1 mg per cm2of carrier surface area over 12 days at 20°C. In some embodiments, the release rate is between about 0.05 mg and about 1.5 mg per cm2over 12 days, between about 0.1 mg and about 2.0 mg per cm2over 12 days, or between about 0.2 mg and about 1.8 mg per cm2over 12 days at 20°C.

[0163] In some embodiments, the carrier has dimensions other than 4cm x 4cm while maintaining equivalent SO2 release characteristics. In some embodiments, the carrier has dimensions of about 2cm x 8cm, about 3cm x 5cm, about 5cm x 3cm, or about 6cm x 2.5cm, each providing approximately 15-17 cm2of surface area. In some embodiments, the carrier is circular with a diameter of about 4.5 cm, providing approximately 16 cm2of surface area. In some embodiments, the carrier is oval-shaped with dimensions of about 5cm x 3.2cm.

[0164] In some embodiments, the thickness of the carrier varies from the 150 micron standard while maintaining effective SO2 release. In some embodiments, the carrier thickness is between about 100 microns and about 300 microns, between about 120 microns and about 200 microns, or between about 130 microns and about 180 microns. In some embodiments, the carrier thickness is about 100 microns (±10%), about 125 microns (±10%), about 175 microns (±10%), about 200 microns (±10%), or about 250 microns (±10%).

[0165] In some embodiments, the SO2 release rate is measured over different time periods while maintaining proportional release characteristics. In some embodiments, the carrier emits between about 0.6 mg and about 16.7 mg of SO2 over 8 days at 20°C. In some embodiments, the carrier emits between about 1.35 mg and about 37.5 mg of SO2 over 18 days at 20°C. In some embodiments, the carrier emits between about 1.8 mg and about 50 mg of SO2 over 24 days at 20°C.

[0166] In some embodiments, the temperature dependence of SO2 release is characterized more precisely. In some embodiments, the release rate increases by a factor of about 1.5 to about 2.5 when temperature increases from 20°C to 40°C. In some embodiments, the release rate at 4°C is about 0.3 to about 0.7 times the release rate at 20°C. In some embodiments, the release rate at 30°C is about 1.2 to about 1.6 times the release rate at 20°C.

[0167] In some embodiments, the carrier is designed with variable thickness across its surface to provide controlled release patterns. In some embodiments, the carrier has a thicker central region of about 180-200 microns and thinner edge regions of about 120-140 microns. In some embodiments, the carrier has a gradient thickness varying from about 100 microns at one edge to about 200 microns at the opposite edge.

[0168] In some embodiments, multiple smaller carriers are used to achieve equivalent SO2 release. In some embodiments, two carriers of about 2cm x 2cm each (total 8 cm2) are used together. In some embodiments, four carriers of about 2cm x 1cm each (total 8 cm2) are used in combination. In some embodiments, the multiple carriers are positioned at different locations within a container to provide more uniform SO2 distribution.

[0169] In some embodiments, the carrier surface area to volume ratio is optimized for specific release characteristics. In some embodiments, carriers with surface areas between about 10 cm2and about 25 cm2provide proportionally scaled SO2 release rates. In some embodiments, carriers with surface areas of about 8 cm2, about 12 cm2, about 20 cm2, or about 24 cm2are used depending on the specific application requirements.

[0170] It is important to reiterate that emission doesn’t constitute migration into food. SO2 emission from the carrier, ideally intro the local atmosphere, is measured by the Monier-Williams or LCMS FDA techniques (the latter from FERA). The Monier-Williams Test may be used to measure migration of the SO2 from the carrier into the food. Both are useful tests. Release rate may therefore be established by trapping emitted SO2 in a similar way to that used in the FDA technique above, using formaldehyde, or via using the hydrogen peroxide solution in the Monier-Williams technique.

[0171] In some embodiments, suitable containers and / or uses for the carrier are for fruits (including grapes, blueberries, strawberries), meat, vegetables and baked goods (such as bread itself or other bread products such as croissants).

[0172] In some embodiments, the containers are suitable for citrus fruits such as oranges, lemons, limes, and grapefruits. In some embodiments, the containers are suitable for stone fruits such as peaches, plums, apricots, and cherries. In some embodiments, the containers are suitable for tropical fruits such as bananas, pineapples, mangoes, papayas, and avocados. In some embodiments, the containers are suitable for berries such as blackberries, raspberries, cranberries, and gooseberries.

[0173] In some embodiments, the containers are suitable for leafy vegetables such as lettuce, spinach, kale, arugula, and cabbage. In some embodiments, the containers are suitable for root vegetables such as carrots, potatoes, sweet potatoes, turnips, and radishes. In someembodiments, the containers are suitable for cruciferous vegetables such as broccoli, cauliflower, Brussels sprouts, and bok choy. In some embodiments, the containers are suitable for vine vegetables such as tomatoes, cucumbers, peppers, and eggplants.

[0174] In some embodiments, the containers are suitable for different types of meat including poultry such as chicken, turkey, and duck. In some embodiments, the containers are suitable for red meat such as beef, pork, and lamb. In some embodiments, the containers are suitable for processed meats such as sausages, deli meats, and cured meats. In some embodiments, the containers are suitable for seafood including fish, shellfish, and crustaceans.

[0175] In some embodiments, the containers are suitable for various baked goods including pastries such as Danish pastries, muffins, and scones. In some embodiments, the containers are suitable for cakes, cookies, and biscuits. In some embodiments, the containers are suitable for pizza dough, tortillas, and flatbreads. In some embodiments, the containers are suitable for specialty breads such as sourdough, whole grain breads, and gluten-free breads.

[0176] In some embodiments, the containers are suitable for dairy products such as cheese, yogurt, and milk-based products. In some embodiments, the containers are suitable for prepared foods such as salads, sandwiches, and ready-to-eat meals. In some embodiments, the containers are suitable for nuts and seeds. In some embodiments, the containers are suitable for dried fruits and dehydrated vegetables. In some embodiments, the containers are suitable for herbs and spices, both fresh and dried.

[0177] In some embodiments, the containers are designed with different configurations for specific food types, such as perforated containers for items requiring air circulation, or sealed containers for items requiring modified atmosphere packaging. In some embodiments, the containers include compartmentalized sections for storing different food items separately while maintaining antimicrobial protection for all compartments.

[0178] Sulfur Pads have been used in the past for use in transport from Picker to Packer. These tend to be very large sheets that are draped over large boxes of fruit. They can be indiscriminate and so tend to lead to suphur burns, especially on the fruit nearest them, and therefore food waste. In some embodiments, the preset carrier is designed for the packer to consumer transportation and use. In some embodiments, the carrier is therefore a sticker, although it may be a lid or placed in or as part of a container. In some embodiments, the “carrier” is the sticker or similar, and a “container” is the tray, punnet, box etc that the carrier sits in with and to protect the food.

[0179] The use of K+ in the present carrier, and at the ranges provided, is a technological improvement over the use of Na+. One example of this is that K+ is more thermally stable andone of the benefits of this is that the plastic carrier comprising the active KMB, in some embodiments, can be formed using a Compounding process, rather than a Masterbatch process. In certain embodiments, for example where the plastic material comprises or consists of one or both of PP (Polypropylene) and LPDE (Low Density Poly Ethylene), we have found that heating the plastic above a certain temperature allows the compounding process to be used. This is primarily because once the melt of the polymer is achieved, heating further reduces the viscosity of the plastic matrix low enough to enable mixing the additive without compromising the thermal stability of potassium metabisulfite. The temperature is approx. 170C.

[0180] Another example of this is that K+ and Sulphite ions dissociate from each other, thereby releasing SO2, at a more controlled rate than is the case for the corresponding Na+ salt. This allows slower release of SO2. This slower release is a technological improvement as it can prevent sulfur burns on an associated food product, and reduced or negligible sulfur burns lead to reduced food waste. In the case of KMB, when used with LDPE, there is up to around a 40C difference in thermal dissociation temperature.

[0181] This may mean that SO2 is released at 40C lower temp for KMB vs NaMB in the carrier, referencing the environmental control mentioned above. It is thought that the LDPE is making KMB more thermally stable by around 40C. In some embodiments, therefore, where the plastic material is LDPE, then a significant benefit and technological improvement is that the LDPE imparts thermal stability on the KMB which would otherwise degrade during the formation of the carrier.

[0182] The slow release of SO2 from KMB is technological improvement over existing sulfur pad technology, which release SO2 more rapidly from NaMB. In particular, these sulfur pads use accelerants and require moisture activation.

[0183] The KMB in the carrier is preferably active KMB. This means that at least 70%, ideally at least 80% or at least 90% or at least 95% of the KMB is present in the salt form in the formed carrier and thus able to form and release SO2 gas from the carrier.

[0184] Factors for slow or controlled release of SO2.

[0185] One of the factors that results in a slower or more controlled release profile for the SO2 is the chemistry of the K+ and Sulphite ions in the KMB salt, for example the thermal dissociation temperature of the KMB salt.

[0186] Another factor is KMB salt particle size. An example particle size range is, in some embodiments, 1-500 microns and, in some embodiments, is 10-50 microns, with ranges around 20-50, 20-40, 20-30, 15-30, 15-40, 15-50, and 30-50 microns preferred. An example particle size range is 10 to below 50 microns, with ranges around 20 to below 50, 20 to below40, 20 to below 30, 15 to below 30, 15 to below 40, 15 to below 50, and 30 to below 50 microns preferred. These may be average particle sizes, for example the mode average; the mean average; or median average. These may be measured by light scattering using known techniques. For example a Malvern Panalytical Particle Size Analyzer may be sued to determine the additive particle size. In some embodiments, a particle size of approx. 25 microns is used. 10 or 15 microns to 25 or 50 microns is a preferred range in some embodiments.

[0187] In some embodiments, the particle size range is 5-100 microns, 8-80 microns, 12-60 microns, or 18-45 microns. In some embodiments, narrower particle size distributions are preferred, such as 22-28 microns, 20-35 microns, or 15-25 microns.

[0188] These may be average particle sizes, for example the mode average; the mean average; or median average. In some embodiments, the particle size distribution is characterized by D10, D50, and D90 values, where D10 represents the size below which 10% of particles fall, D50 represents the median particle size, and D90 represents the size below which 90% of particles fall. In some embodiments, the D90 value is less than 50 microns, less than 40 microns, or less than 35 microns. In some embodiments, the D10 value is greater than 5 microns, greater than 8 microns, or greater than 10 microns.

[0189] These may be measured by light scattering using known techniques. For example a Malvern Panalytical Particle Size Analyzer may be used to determine the additive particle size. In some embodiments, alternative particle size measurement techniques are employed, such as dynamic light scattering (DLS), laser diffraction, sieve analysis, or microscopy -based image analysis. In some embodiments, scanning electron microscopy (SEM) is used to verify particle size measurements and assess particle morphology. In some embodiments, particle size is measured using a Beckman Coulter LS 13 320 Laser Diffraction Particle Size Analyzer, a Horiba LA-960 Laser Scattering Particle Size Distribution Analyzer, or equivalent instrumentation.

[0190] In some embodiments, a particle size of approx. 25 microns is used. In some embodiments, specific target particle sizes include approximately 15 microns, 20 microns, 30 microns, 35 microns, or 40 microns. 10 or 15 microns to 25 or 50 microns is a preferred range in some embodiments.

[0191] In some embodiments, the particle size is optimized based on the plastic carrier matrix material, with smaller particles (10-25 microns) preferred for thinner films and larger particles (25-50 microns) suitable for thicker carriers. In some embodiments, the particle size is selected to optimize the release rate of SO2, with smaller particles providing faster initialrelease and larger particles providing more sustained release over time. In some embodiments, bimodal or multimodal particle size distributions are employed, combining different particle size ranges to achieve desired release profiles.

[0192] In some embodiments, the KMB particles are subjected to surface treatment or coating to modify their release characteristics or improve compatibility with the plastic matrix. In some embodiments, the particles are spherical, irregular, or have controlled morphologies such as rod-like or platelet shapes. In some embodiments, the particle size is controlled through specific grinding or milling processes, such as jet milling, ball milling, or cryogenic grinding, with jet milling being preferred for achieving uniform particle sizes in the 10-50 micron range.

[0193] Without being bound by theory, it is thought that the range of additive particle sizes of approx. 15 microns to 25 microns, especially approx. 20 microns, is advantageous as the salt crystals are thought to create a porosity or permeability in the plastic material. When the plastic is LDPE, which seems to work especially well and provide release rates that leads to long product lives (antimicrobial effect) and little to no sulfur bum, so overall low food wastage. Another benefit is also to stay within current labelling guidelines.

[0194] Another factor is the ambient temperature of the carrier (and optionally any container with said carrier), for example between the packer and sale to the consumer. Such a temperature range is typically from about 1°C to 25°C, in some embodiments. The carrier is can operate in 35C in hotter climates, but typically the food is affected by the heat anyway. In some embodiments, the preferred temperature for use is around 1°C to around 20°C or 25°C.

[0195] In some embodiments, the carrier is designed to operate effectively across a broader temperature range, from about -5°C to about 40°C, to accommodate various storage and transportation conditions including frozen storage, refrigerated transport, ambient warehouse conditions, and elevated temperatures during summer shipping. In some embodiments, the carrier maintains consistent SO2 release characteristics within a narrower temperature range of about 2°C to about 8°C, corresponding to typical refrigerated storage conditions for fresh produce.

[0196] In some embodiments, the carrier is optimized for specific temperature zones, such as tropical climates where ambient temperatures may reach 30°C to 45°C, with the carrier formulation adjusted to prevent excessive SO2 release at these elevated temperatures. In some embodiments, the carrier includes temperature-responsive elements that modulate SO2 release rates based on ambient conditions, providing higher release rates at lower temperatures and reduced release rates at higher temperatures to maintain optimal antimicrobial efficacy while preventing food damage.

[0197] In some embodiments, the carrier is designed for cold chain applications with operating temperatures from about -2°C to about 4°C, suitable for meat, dairy, and highly perishable produce storage. In some embodiments, the carrier functions effectively in controlled atmosphere storage facilities where temperatures are maintained between about 0°C and about 2°C with specific humidity and gas composition controls.

[0198] In some embodiments, the carrier incorporates thermal stability enhancers that maintain potassium metabisulfite integrity and controlled release characteristics even when exposed to temperature fluctuations of ±10°C or ±15°C from the target storage temperature. In some embodiments, the carrier is formulated to compensate for the Arrhenius relationship between temperature and chemical reaction rates, with the plastic matrix composition adjusted to provide relatively constant SO2 release rates across the intended temperature range.

[0199] In some embodiments, the carrier includes temperature indicator elements that provide visual confirmation of exposure to temperatures outside the recommended range, helping to ensure food safety and quality. In some embodiments, the carrier is designed with multiple release zones or layers that activate sequentially as temperature increases, providing adaptive antimicrobial protection based on storage conditions.

[0200] Another factor is the size and / or shape of the carrier. Example carrier sizes are 4cm by 4cm. Example shapes of the carrier are cuboid (square or rectangular), circular or oval shaped. We have also used 20x8 cm2 films in of trials as a film.

[0201] Another factor is the concentration of the KMB salt in the carrier. Example ranges include 5%-20% w / w, in some embodiments, and 10-25%, 15-25%, 10-20%, 15-25%, 18-25%, 18-22%, 19-25% 19-23%, 19-22% and 20-23% w / w KMB to plastics material, especially LDPE or PP.

[0202] US Patent Publication US 2005106380 A1 (Bernard) filed in 2003, discloses a NaMB system that releases SO2 from the Na+ sulphite salt (NaMB). It states in its Examples that a release rate of up to 186 ppm SO2 from NaMB is possible using any cation, but this is clearly only for instances where the cation is Na+. Bernard’s temperature range was limited to between HOC and 150 C, and mostly toward the lower end, in order to avoid degradation of the NaMB and thereby ensure their aim of fast release of sulfur dioxide gas. It is a focus of the present invention that the release of SO2, this time from KMB, is slow, in contrast to Bernards fast release.

[0203] Bernard also focuses on the fact that small particles of NaMB, i.e. those having a high surface area to volume ratio, are useful for faster release rates of SO2 from NaMB. In contrast, we have found that for slow release of SO2 from KMB, these smaller particles in therange of a D90 mof 10-50 (or 10 up to below 50) microns and ranges within that as described herein, particularly a D90 around 25 microns (average particle size as measured by scattered light) are required.

[0204] In a technological improvement, we have shown in our Examples that a desired release rate of SO2 given above are only possible if the K+ cation is used.

[0205] References herein to release rate should be understood to refer to SO2. And it should be understood to include reference to emission rate, to the extent that the there is no conflict between them. Suitable units are PPM (Parts Per Minute). The gas released (or emitted) is SO2 and a suitable test for measuring SO2 release (or emission) may be tested via the well-known Monier Willaims test, an example of which is given in Example 4 herein or in US 2005106380 A1 (Bernard), which is incorporated herein by reference. Food migration tests into food are useful.

[0206] SO2 fumigants for harvested grapes has been used to attempt to ensure long distance food transportation from grower to packer; so-called SO2 pads used in shipping. These often release a lot of SO2 and prize liberating the maximum amount of SO2 without breaching the limit of SO2 migration. However, this often causes sulfur burns and contributes to rejections at the packer. This leads to food waste, which is damaging to the environment as more food needs to be grown that is actually consumed, as well as economic loss for small farmers in particular. In contrast, our solution differs by, inter alia, allowing a focus on usage at the packer to consumer stage, for example by presenting in the size ranges described herein, in particular around 16cm2 (approx. 4cm x 4cm) as described herein.

[0207] One result of this is, in some embodiments, to liberate (e.g. release, emit) smaller quantities of SO2. Ideally, this is the smallest quantity of SO2 that yields effective results in terms of restricting microbe growth. Ideally, this rate of release or emission is also lower (in some cases magnitudes lower) than the safety limits of SO2. It is therefore an advantage to stay below these release / emission rates to reduce food wastage and reduce or eliminate safety concerns. Furthermore, above certain SO2 levels, or release / emission rates, food needs to be labelled as containing sulphites. This is commercial burdensome, and can alarm consumers, and so it is a technological improvement that the present invention is able to provide release / emission rates below these thresholds.

[0208] Thus, the concept of slow release (or slow emission) has been developed as a technological improvement. In exemplary embodiments, the release / emission rate is described herein. Innovations include one or more of:• carrier matrix,1. for example LDPE,• SO2 releasing salt,1. i.e. KMB,• % loading,1. for example 0.1% to 50% (w / w) KMB in the carrier, and other exemplary ranges provided herein;• additive particle size,1. for example 10 to 50 micrometre (microns), especially ranges around 25 microns size particles (when measured by light scattering),• Carrier (e.g. a sticker) shape and dimensions,1. The surface area and volume can affect release, in particular the surface area to volume ratio. This can be determined by testing the release of SO2 and food migration of SO2 from different shaped carriers. Exemplary shape and surface area to volume ratios are provided herein.

[0209] Also important may be:• The successful production of the carrier with the KMB salt without significantly destroying the KMB additive.• The use of LDPE (Low-Density Poly-Ethylene) allows lower temperatures to be used as it has a lower melting point than many other PEs or PPs (Poly-Propylenes).• Thus, in some embodiments, the combination of LPDE and KMB is particularly useful. In addition, certain grades of LDPE are preferred, such as those having a high or very high molecular weight (MW), for example plastics, especially LDPE, having MFI 0.5.Step Convention Our Solution Outcome if not performedAdditive selection Sodium metabisulfite We used potassium Additive does not is the conventional metabisulfite work when ingredient for SO2 compounded into generators plasticAdditive grinding Conventionally Additive is jet milled to 25 Lower performance additives are added micron D90 specification, so evidenced by in in a semi coarse ranges 10-50 microns are most house microbiology grade around 100 useful testing. micron or larger.Additive grinding Typically cheap Jet milling is used, Additive clumps or alternatives such as degrade under ball milling is used. shear stress.Plastic matrix Polyolefins are Uses LDPE. PP and higher selection expected to work melting plastic will such as PP and LDPE cause additive degradation.

[0210] MFI (Melt Flow Index): As used herein, the term " MFI" or "melt flow index" refers to a measure of the ease of flow of the melt of a thermoplastic polymer. MFI is typically expressed in grams per 10 minutes (g / 10 min) and is determined by measuring the mass of polymer that flows through a standardized capillary die under specified conditions of temperature and pressure over a 10-minute period, as defined by standard test methods such as ASTM DI 238 or ISO 1133. A lower MFI value indicates higher molecular weight and higher melt viscosity, while a higher MFI value indicates lower molecular weight and lower melt viscosity. In the context of this invention, MFI is particularly relevant for characterizing the flow properties of polyethylene materials, especially low-density polyethylene (LDPE), where specific MFI values such as 0.5 are preferred for achieving optimal processing characteristics while maintaining the integrity of temperature-sensitive additives like potassium metabisulfite during manufacturing processes.

[0211] Thus, in some embodiments, the combination of LDPE and KMB is particularly useful. In addition, certain grades of LDPE are preferred, such as those having a high or very high molecular weight (MW), for example plastics, especially LDPE, having MFI 0.5.

[0212] In some embodiments, the melt flow index (MFI) of the LDPE is between about 0.1 and about 2.0, between about 0.2 and about 1.5, between about 0.3 and about 1.2, or between about 0.4 and about 0.8. In some embodiments, the MFI of the LDPE is about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1.0,about 1.2, about 1.5, or about 2.0. In some embodiments, the MFI of the LDPE is 0.5 ± 0.1, 0.5 ± 0.2, or 0.5 ± 0.3.

[0213] In some embodiments, the high or very high molecular weight LDPE provides improved melt strength during processing, which is particularly advantageous when incorporating temperature-sensitive additives such as potassium metabisulfite. In some embodiments, the low MFI value indicates higher molecular weight and provides better processability at lower temperatures, thereby reducing the risk of thermal degradation of the potassium metabisulfite during manufacturing.

[0214] In some embodiments, the LDPE has a molecular weight (Mw) of at least about 100,000 g / mol, at least about 150,000 g / mol, at least about 200,000 g / mol, at least about 250,000 g / mol, or at least about 300,000 g / mol. In some embodiments, the LDPE has a molecular weight between about 100,000 g / mol and about 500,000 g / mol, between about 150,000 g / mol and about 400,000 g / mol, or between about 200,000 g / mol and about 350,000 g / mol.

[0215] In some embodiments, the combination of LDPE with MFI 0.5 and potassium metabisulfite allows for processing temperatures as low as about 150°C to about 170°C, which is significantly lower than typical processing temperatures for other polyolefins such as polypropylene. In some embodiments, this lower processing temperature helps preserve the integrity and antimicrobial efficacy of the potassium metabisulfite while still achieving adequate melt flow and processability for film formation.

[0216] In some embodiments, the LDPE grade selected has a density between about 0.910 g / cm3and about 0.930 g / cm3, between about 0.915 g / cm3and about 0.925 g / cm3, or about 0.920 g / cm3. In some embodiments, the LDPE exhibits good gas permeability properties that facilitate the controlled release of SO2 from the incorporated potassium metabisulfite.

[0217] In some embodiments, the carrier has a 4:1 ratio (20% w / w) of KMB to plastic material. In particular, a 4:1 ratio (20 w / w) KMB to LDPE is preferred. This is he KMB “loading” in the plastic material.

[0218] LDPE is, in some embodiments, preferred as the plastic material, for the reasons provided herein, including permeability. LDPE with an MFI of around 0.3 to 2.5, in particular approx. 0.5 is therefore, in some embodiments, preferred.

[0219] In some embodiments, a particle size of KMB of approx. 5 microns in the carrier product is ideal. This is, without being bound by theory, because it provides a preferred SO2 release rate (at room temperature), especially but not exclusively when LDPE, in particular low MFI such as 0.5, and / or approx. 20% KMB w / w are used together with this approx, particlesize of D90 25 microns used in the manufacturing process or D90 5 microns in the carrier product. Reference here to particle size is with respect to the final product, the carrier.

[0220] In some embodiments, a combination of: an approx. 4:1 ratio (20% w / w) of KMB to plastic material; and LDPE (especially with an MFI of around 0.5) is preferred.

[0221] In some embodiments, a combination of: an approx. 4:1 ratio (20% w / w) of KMB to plastic material; a particle size of KMB of approx. 5 microns in the carrier product, is preferred.

[0222] In some embodiments, the potassium metabisulfite has a particle size of approximately 5 microns in the carrier product. Reference herein to a 5 micron particle size may also include the following variations. In some embodiments, the particle size is between about 3 microns and about 7 microns, between about 4 microns and about 6 microns, or between about 4.5 microns and about 5.5 microns. In some embodiments, the particle size is about 3 microns, about 4 microns, about 5 microns, about 6 microns, or about 7 microns.

[0223] In some embodiments, the approximately 5 micron particle size is achieved through specific grinding or milling processes optimized for potassium metabisulfite. In some embodiments, jet milling is used to achieve the 5 micron particle size with minimal particle degradation. In some embodiments, cryogenic grinding is employed to maintain particle integrity while achieving the target size. In some embodiments, ball milling followed by optional classification is used to obtain particles of approximately 5 microns. In some embodiments, jet milling followed by optional classification is used to obtain particles of approximately 5 microns.

[0224] In some embodiments, the particle size distribution around 5 microns is characterized by a D50 value of approximately 5 microns with a narrow distribution span. In some embodiments, at least 80%, at least 90%, or at least 95% of the particles fall within the range of 3-7 microns. In some embodiments, the particle size distribution has a D10 value of about 3 microns and a D90 value of about 7 microns.

[0225] In some embodiments, processing conditions are optimized to prevent particle size reduction during melt processing, including temperature control below 180°C and reduced shear rates. In some embodiments, the particle size is verified post-processing to ensure minimal degradation from the target 5 micron size.

[0226] In some embodiments, the 5 micron particle size provides optimal balance between processability and antimicrobial efficacy. In some embodiments, particles of this size distribute more uniformly throughout the plastic matrix compared to larger particles, reducing the formation of concentration gradients. In some embodiments, the 5 micron size facilitatescontrolled release of SO2 over extended periods while maintaining structural integrity of the carrier.

[0227] In some embodiments, a combination of: a particle size of KMB of approx. 5 microns in the carrier,; and LDPE with an MFI or around 0.5 is preferred.

[0228] In some embodiments, a combination of: an approx. 4:1 ratio (20% w / w) of KMB to plastic material; LDPE (especially with an MFI of around 0.5) is preferred; and a particle size of KMB of approx. 5 microns in the carrier, is preferred.

[0229] For certain carrier usages, for example a sticker, a thickness of approx. 150 microns (+ / - 10%) is preferred, in some embodiments. For certain carrier usages, for example a sticker, a sizing of approx. 4cm x 4cm square (16cm2) is preferred, in some embodiments. For certain carrier usages, for example a sticker, athickness of approx. 150 microns (+ / - 10%) and a sizing of approx. 4cm x 4cm square (16cm2) is preferred, in some embodiments. A surface area to volume ratio equivalent to approx. 16cm2 to a thickness of approxl50 microns (+ / - 10%) is therefore provided.

[0230] In some embodiments, the surface area to volume ratio is equivalent to approximately 12cm2to a thickness of approximately 120 microns (+ / - 10%), approximately 20cm2to a thickness of approximately 180 microns (+ / - 10%), or approximately 25cm2to a thickness of approximately 200 microns (+ / - 10%). In some embodiments, the thickness tolerance is maintained at + / - 5%, + / - 15%, or + / - 20% to accommodate different manufacturing processes and quality control requirements.

[0231] In some embodiments, the surface area to volume ratio is optimized for different carrier geometries, such as rectangular carriers with dimensions of approximately 3cm x 5.3cm to a thickness of approximately 140 microns, circular carriers with a diameter of approximately 4.5cm to a thickness of approximately 160 microns, or oval-shaped carriers with dimensions of approximately 5cm x 3.2cm to a thickness of approximately 145 microns. In some embodiments, the carrier incorporates variable thickness profiles, with thicker central regions of approximately 170-190 microns and thinner edge regions of approximately 130-150 microns to provide controlled release characteristics.

[0232] In some embodiments, the surface area to volume ratio is adapted for different plastic materials, with LDPE carriers maintaining the 16cm2to 150 micron ratio, while PP carriers utilize approximately 16cm2to 175 microns (+ / - 10%) to account for different processing requirements and gas permeability characteristics. In some embodiments, degradable plastic carriers such as PLA maintain approximately 16cm2to 140 microns (+ / -10%) to optimize SO2 release while ensuring structural integrity throughout the intended use period.

[0233] In some embodiments, the surface area to volume ratio is scaled proportionally for different application requirements, such as 8cm2to 75 microns for smaller packaging applications, 32cm2to 300 microns for extended release applications, or 64cm2to 600 microns for industrial-scale antimicrobial protection. In some embodiments, multiple carriers with the standard 16cm2to 150 micron ratio are used in combination to achieve equivalent total surface area while maintaining optimal individual carrier performance characteristics.

[0234] Various forming methods are possible for different uses. In some embodiments, the carrier is for use in a punnet (for grapes, strawberries and other fruit, or for meat). Cast Film Extrusion can be used here and the resulting sheet may have a thickness of 150 pm (± 15%) and a width of 320 mm and length of 130 m. Alternatively Blown Film Extrusion may be sued here and the resulting sheet may have a thickness of 150 pm (± 15%) and a width of 320 mm and length of 130 m. These are then cut down to smaller carriers, for example the approx. 4x4cm (approx. 16cm2) carriers. Alternatively, For Bread Bags, a blown film extruded carrier is preferred and an exemplary resulting sheet may have a thickness of 37 micron (± 15%) and a width of 320 mm.

[0235] Provided, therefore, is a cast or blown film extruded carrier (for example a sticker for use in a punnet) having an approx, thickness of 150 pm (± 15%), which may be provided as carriers of approx. 4x4cm (approx 16cm2). Also provided is a blown film extruded carrier (for example for use in a bread bag) having an approx, thickness of 370 pm (± 15%), which may be provided as carriers in a range of sizes, for examples of approx. 4x4cm (approx 16cm2). Also provided are punnets and bread bags comprising said carries.

[0236] In some embodiments, the methods, both compounding and / or masterbatch, may include a step of jet milling to provide the additive particle size distribution. Without being bound by theory, it is thought that jet milling is advantageous as it breaks down the particles without heating them up.

[0237] In some embodiments, in the methods, both compounding and / or masterbatch, the plastic material is LDPE. In some embodiments, the plastic material has a low MFI. In some embodiments, the low MFI of the plastic material can be in the range of 0.3-2.5. In some embodiments, the LDPE has a low MFI. In some embodiments, the low MFI of the LDPE can be in the range of 0.3-2.5. In some embodiments, the low MFI of the LDPE can be approx.0.5, and as described herein.EXAMPLESExample 1: Manufacture and Characterization of Thick Film Plastics Containing Potassium MetabisulfiteManufacture of Thick Film Plastics Containing Potassium MetabisulfiteGrinding Process:

[0238] Potassium metabisulfite (KMB) was ground to a lower micron range by a dry grinding process for future extrusion.Extrusion Process:

[0239] Masterbatch: A mixture containing 30% of dry powderized active KMB and 70% of dry powderized polypropylene (PP Sabie) was placed into the TMS oven at 80°C for at least an hour. Extrusion was performed in a Process 11 Parallel Twin Screw Extruder (Thermo Scientific), using the heating profile from doser as 150, 170, 185, 190, 195, 195, 185 and 170 at a dosing speed of 30% with the extruder set to 185 RPM. The extruded masterbatch was cooled and pelletized using a Varicut Pelletiser (Thermo Scientific) at 3 max speed at setting L3, to form the granular masterbatch. The masterbatch pellets were stored in zip lock bags and stored in the fridge for freshness.

[0240] Masterbatch dilution: Masterbatch pellets were mixed with PP (Sabie) pellets at target ratios, then extruded at 170°C in the twin screw extruder using the heating profile from doser as 150, 170, 185, 190, 195, 195, 185 and 170 at a dosing speed of 30% with the extruder set to 185 RPM. The resultant filaments were then pelletized by the Varicut Pelletiser at 3 max speed at setting L3 to obtain the end product having a desirable final concentration of KMB (for example, a film containing 5% KMB was produced with 16.6% masterbatch and 83.3% sabic polypropylene). Pellets obtained were stored in zip lock bags and stored in the fridge for freshness.Production of Plastic Thick Film:

[0241] The resulting pellets from the masterbatch dilution extrusion process were then heat pressed (2 g) at 170°C between two aluminum plates. The aluminum plates were cleaned with ethanol to eliminate any sticky residue on the plates. The films were then cooled to produce a thick film for testing. The thick films were then stored in the fridge for freshness, and used as is for the characterization studies.Characterization of Thick Film Plastics Containing Potassium MetabisulfiteAntifungal Activity of 1% and 2% KMB thick films

[0242] Potassium metabisulfite was incorporated into PP at either 1 wt % or 2 wt %, and the antifungal efficacy was measured at 24 hours of contact with the yeast C. albicans and the mold A. brasiliensis. As shown in Figure 11, C. albicans showed an almost 4 log (99.96%) reduction for both 1 wt % and 2 wt % KMB, while A. brasiliensis exhibited a 3 log (99.86%) reduction when exposed to 1 wt % KMB and almost a 3.5 log (99.97%) reduction when exposed to 2 wt % KMB for 24 hours, demonstrating that potassium metabisulfite possessed high antifungal activities in this setting.Food Migration Studies:

[0243] The overall and specific food migration of the thick films containing various concentrations of potassium metabisulfite (KMB) were performed. Food simulant E - Tenax was assigned as representative of dry, non-fatty foods, a category where unpeeled and uncut fruits are placed within Commission Regulation (EU) 10 / 2011. To perform the experiment, film samples were kept for 10 days at 40°C. At the end of the experiment, extracts were taken and tested using relevant instruments. Experiments were performed in triplicate and mean results were taken. Tables 1-6 below show the results for 3% (w / w), 5% (w / w), and 8% (w / w) KMB containing thick films made of PP.

[0244] Tables 1 and 2 show the results for thick films containing 3% (w / w) KMB. Overall migration of the films was <0.3 mg / dm2, whereas the specific migration was <0.01 mg / kg for potassium and 0.005 mg / kg for sulfites. The Specific Migration Limit (SML) for potassium is 0.01 mg / kg, whereas it is 10 mg / kg for sulfites. Therefore, the results show that no migration above the allowed limits is expected to occur for foods covered by the simulant used and under conditions equivalent to or less severe than the testing conditions.Table 1. Overall migration of thick films containing 3% (w / w) KMB:: TO-; W<® 1 (UOSCdomHWiWlp: 18 ^ WCOw^mi|pto grt?:am<0.30 <0.30 <03 033 dof ortw)Table 2. Specific migration of thick films containing 3% (w / w) KMB«had: TES'AC 8U ( UK )Elh ne*C«sntsot tb h: W da dt CGsmaa ams: 03^<0.01 ^>1 w* o,w (IWM o.«

[0245] Tables 3 and 4 show the results forthick films containing 5% (w / w) KMB. Overall migration of the films was <0.3 mg / dm2, whereas the specific migration was <0.01 mg / kg for potassium and 0.005 mg / kg for sulfites. The Specific Migration Limit (SML) for potassium is 0.01 mg / kg, whereas it is 10 mg / kg for sulfites. Therefore, the results show that no migration above the allowed limits is expected to occur for foods covered by the simulant used and under conditions equivalent to or less severe than the testing conditions.Table 3. Overall migration of thick films containing 5% (w / w) KMBOwOwp > w < w*s: 14 ' 004SOM.so*'54130 <30 4130 3.33 « exit xKtsoryTable 4. Specific migration of thick films containing 5% (w / w) KMB4*01® TF. S AC. £'3Smutent Tw (Ethw$ whelmsGootrn 0 owwop Wisp ® WCCo?t44 w«4ss4\ X4 'i 4;' o.m 401 Wt am 0.0® W

[0246] Tables 5 and 6 show the results for thick films containing 8% (w / w) KMB. Overall migration of the films was <0.3 mg / dm2, whereas the specific migration was <0.01 mg / kg for potassium and 0.005 mg / kg for sulfites. The Specific Migration Limit (SML) for potassium is 0.01 mg / kg, whereas it is 10 mg / kg for sulfites. Therefore, the results show that no migration above the allowed limits is expected to occur into foods covered by the simulant used and under conditions equivalent to or less severe than the testing conditions.Table 5. Overall migration of thick films containing 8% (w / w) KMBWOod:: TES^Wt (U WC»m; 10 > 41COvoos3 tent; w mspof®wisssi^din54130 4130 < 0.30 <03 d 3xTable 6. Specific migration of thick films containing 8% (w / w) KMBWM MM Tw [SW WMSWCorfet tWtep IQ^^W’G'CM®0,33 < Wmsjscws M.W Ci _. W <003 < OO1 <301 OOIwFood Shelflife Test:

[0247] A food shelf life test was performed for grape packaging to evaluate the plastic’s ability to extend the shelf life of grapes packed in carbon dioxide modified atmosphere packaging.

[0248] The thick films were put in the punnet under the grapes and plastic lids were adhered on top of the punnet in the presence of carbon dioxide. Thirty -five replicates were used from each experimental group and 500 g punnets were stored at 20°C for 22 days. The grapes were checked for the evaluation every 2-3 days. At the end of the 22 days, organoleptic properties were tested by a panel. The samples included (i) P: Polypropylene (PP) film (control); and (ii) K: 5% (w / w) Potassium metabisulfite (KMB) thick film.

[0249] As shown in Figure 1, the punnets containing PP film lasted for only 10 days, with the last punnets being removed on day 10 due to the spoilage, whereas 28 out of 35 K samples were rejected in total at the end of Day 10. The results showed that 2% of KMB containing punnets remained in good condition after 22 days.

[0250] Table 7 shows the individual assessment of the panelists for KMB containing punnets. On Day 14, sensory evaluation was performed to assess organoleptic properties such as taste, texture, and overall quality by scoring them between the values of 0-4, descriptions of which are given below. A tasting session was not conducted for P samples, which had been discarded at Day 10. External appearance, firmness, crunchiness, texture, sweetness, acidity, and overall flavor of the grape punnets having K sample in ranged from 1.9-2.1 except crunchiness which was 1.6. However, in general the grapes kept in KMB containing film punnets exhibited acceptable values.Table 7. Individual assessment of the panelists for KMB containing punnetsExternal § i § § Would 1 i Firm- Chrunch4 ^Sweet- ^Overall i 1 i Panelist Appear- § ^Texture Acidity 1 pou Comments! hess uness § pess Flavour i 1 i ance §! i Mediocre, i! i ^slightly i i 0 |3 1 k 2 2 U M § i! i Isweet, not § Aery juicy k 2 |2 |2 |2 2 2 k | ] k 3 |3 |2 |2 2 2 kYi 1, \ £...44C § i koo soft, s k 2 jl 1 k 2 2 §2§ pot sweet 5 2 |2 2 4 „£3,„ |2 1 1 1 Y |,62|2 |N | |£..4 § peutral § ^smell, 7 „^„„J £ _ _4 3 p W home ^berries are \ Cl Cl § Aery sharp ^Average 1.9 k ° h-6 k-1 | ()2.0 |0.9 4Y / 3X | |O-RTM,1-Needs improvement, 2-Acceptable, 3-Exceeds expectation, 4-ExcellentExample 2: Manufacture and Characterization of Thick or Thin Film Plastics Containing Potassium MetabisulfiteManufacture o f Thick or Thin Film Plastics Containing Potassium Metabisulfite Grinding Process:

[0251] Potassium metabisulfite (KMB) was ground to a lower micron range by a dry grinding process for future extrusion.Quality Control of the potassium metabisulfite powder:

[0252] For Quality Control (QC) analysis, titration and scanning electron microscopy (SEM) imaging was performed. The titration experiment used a titrant comprising potassiumiodide and iodine to ensure the quality of potassium metabisulfite (KMB) after grinding. SEM was also used to calculate the approximate dimensions of the particles.

[0253] For SEM imaging, first, a carbon tape was placed on an SEM stub to allow conductivity within the sample and obtain an image. For the KMB sample, a thin layer of the ground powder was placed onto the carbon tape with the help of a spatula and an air gun was used to ensure the powder was stuck to the carbon tape. System parameters to obtain the images included: accelerating voltage of 15KV, beam intensity set to point, detector BSD full and vacuum set to high (0.10 Pa).

[0254] SEM images are shown in Figure 2 for KMB powder-HD. SEM imaging was used to identify the dimension profile of the compound and average size was calculated using imaged. Measurements were then exported to excel to determine the average and standard deviation of the measurements within the SEM image.

[0255] The average size of the ground KMB-HD and KMB-Sigma compounds was calculated to be 8.43±10.38 pm and 13.45±6.24 pm, respectively. Because of the irregularities in the shape of the compounds, the average sizes were only an estimate of the dimension profile.Extrusion Process:

[0256] Masterbatch: A mixture containing 30% of dry powderized active KMB and 70% of dry powderized polypropylene (PP Sabie) was placed into the TMS oven at 80°C for at least an hour. Extrusion was performed in a Process 11 Parallel Twin Screw Extruder (Thermo Scientific), using the heating profile from doser as 150, 170, 185, 190, 195, 195, 185 and 170 at a dosing speed of 30% with the extruder set to 185 RPM. The extruded masterbatch was cooled and pelletized using a Varicut Pelletiser (Thermo Scientific) at 3 max speed at setting L3, to form the granular masterbatch. The masterbatch pellets were stored in zip lock bags and stored in the fridge for freshness.

[0257] Masterbatch dilution: The masterbatch pellets were mixed with PP (Sabie) pellets at target ratios and then extruded at 170°C in the twin screw extruder using the heating profile from doser as 150, 170, 185, 190, 195, 195, 185 and 170 at a dosing speed of 30% with the extruder set to 185 RPM. The filaments obtained were then pelletized by the Varicut Pelletiser at 3 max speed at setting L3 to obtain the end product compound at differing concentrations 5%, 10%, 15% and 20% based on masterbatch dilutions. Pellets obtained were stored in zip lock bags and stored in the fridge for freshness.Thick or Thin Film production at Heat Press / Injection Molding:

[0258] Thick film production: Pellets from the masterbatch dilution extrusion process were heat pressed (2 g) at 170°C between two aluminum plates. The aluminum plates were cleaned with ethanol to eliminate any sticky residue on the plates. The films were then cooled to produce a thick film for testing, and were stored in the fridge for freshness.

[0259] Thin fdm production: Pellets of desired concentration were weighed (4 g) and spread between 2 Kapton films. The Kapton films were sandwiched between two stainless steel sheets on each side. Best efforts were maintained to keep the metal sheets and Kapton films cleaned either via dry wipe for the Kapton or IPA for the stainless-steel sheets. The Collins molder was preheated to 164°C for at least 20 minutes, after which the sandwiched sample was loaded into the molder and pressed at a pressure of 5 bar. Once the temperature of the plates hit 160°C, the pressure was maintained for 70 s and then released. The sandwiched sample was removed from the heat press and air dried via waving the kapton sheets in the air whilst the sample was still sandwiched for roughly 2 minutes. The sample was then peeled away and stored. The thin films were cut into 4 pieces of 4x4 cm2(0.5 gram / each) for the trial. The 20% potassium metabisulfite thin films here contained the same quantity of potassium metabisulfite as the 2-gram weight, 5% potassium metabisulfite thick films described in Examples 1 and 2.Characterization of Thick or Thin Film Plastics Containing Potassium Metabisulfite Thermogravimetric Analysis (TGA):

[0260] Thermogravimetric Analysis (TGA) thermograms were obtained using a Q50 Thermogravimetric Analyzer (TA instruments). Thermograms were recorded under an N2 atmosphere at a heating rate of 10 °C min-1, from 25°C (room temperature) to 600°C, with an average sample weight ranging from 15 to 25 mg.

[0261] TGA of 20% KMB and 15% KMB thin film samples are shown in Figures 3-4 and Table 8. The decomposition reaction of potassium metabisulfite (K2S2O5) is given below:

[0262] Thermal degradation of potassium metabisulfite started at around 180°C and continued until 460°C. Two stages of weight loss were observed for all samples. For the 20% KMB thin samples the first weight loss occurred between 180°C - 275°C, the second weight loss happened between 275°C and 475°C. The first weight loss (4.50%) was associated with SO2, whereas the second one is associated with the polymer’s (PP Sabie) degradation andcalculated to be 79.97%. Around 15.53% residue might belong to K2SO3. In order to decide if the residue is only K2SO3, polymer’s TGA was also taken. Because there was no residue associated with PP, the residue in 20% KMB thin films was considered to be associated with K2SO3.

[0263] Further, as shown in Figure 3, the onset of degradation of KMB started at 144°C in the powder sample, whereas the onset of degradation of KMB increased to 202°C in 20% KMB thin films, demonstrating that the thermal stability of KMB was improved by 57°C as a result of its incorporation into the plastic material.

[0264] TGA was performed in triplicate for 20% KMB thin films, with results provided in Table 8 for all 3 samples. First TGA was taken from the first batch, whereas the latter two were taken from the second batch. The results were very similar among all 3 samples, with average ± standard deviation being 4.48±0.08% as associated with SO2 release and 15.75±0.48% as associated with K2SO3.Table 8. Summary of TGA results of 20% thin film samples and 15% thin film sample Sample Mass of sample (mg) SO2 (%) K2SO3 (%) 20% KF * 15.498 4.5 15.5320% thin ** 18.783 4.54 16.320% thin ** 21.737 4.39 15.4315% thin 24.161 2.94 11.54(*) sample from the first batch(**) samples from the second batch

[0265] Similar results were observed for the 15% KMB thin sample where the first weight loss happened at 200°C, second weight loss at 275°C, reaching a plateau at 460°C. The first weight loss (2.94%) was associated with SO2, whereas the second weight loss is again associated with the polymer degradation and calculated to be 86.32%. Around 11.54% residue may belong to K2SO3. Because there is no residue associated with PP, the residue in 15% KMB thin films was considered to be associated with K2SO3.

[0266] In addition, as shown in Figure 4, the onset of degradation of KMB started at 144°C in the powder sample, whereas the onset of degradation of KMB increased to 205°C in15% thin films. This result showed that we improved the thermal stability of KMB around 60°C by incorporating it into PP.Antimicrobial activity

[0267] The antimicrobial activity of KMB incorporated films was assessed in two assays, determining the antimicrobial activity of direct-contact killing and indirect-contact killing (via volatiles).

[0268] Direct-contact killing: To assess the antimicrobial activity of these materials when in direct contact with bacteria, samples were tested following ISO 22196, with minor modifications. Briefly, disks were prepared and cut to 2.5 cm x 2.5 cm. The samples were prepared in two different thicknesses, and the thinner films were prepared at different KMB concentrations (5-20%). A bacterial inoculum, containing -IxlO5CFU / ml, was added to the material’s surface and covered with a coverslip to maximize contact and prevent evaporation. The inoculated samples were incubated for 24 hours at 37°C, after which the surviving bacteria were recovered, serially diluted and plated. After 18-24 hours of growth at 37°C, the colonyforming units were enumerated, and the log reduction from polypropylene (PP) only controls was calculated. As shown in Figure 5, all samples (at either thickness and all concentrations of KMB) were able to eradicate E. coli after 24 hours of contact. Antifungal testing was also conducted following a modified version of ISO 22196, with some parameters changed to suit culturing and testing of yeast and mold species. A fungal inoculum containing -IxlO7CFU / ml of C. albicans or A. brasiliensis was prepared for testing KMB films (1% and 2%). Inoculated samples were incubated at 30°C for 24 hours. As per bacteria testing, surviving fungi were recovered, serially diluted and plated, and the log reduction from polypropylene (PP) only controls was calculated.

[0269] Indirect-contact killing: An in-house, indirect-contact antimicrobial test was developed to determine the antimicrobial activity of the volatiles being released, to better mimic the application scenarios in which there is no contact between the samples and the product, where the activity relies solely on the release of an antimicrobial gas (e.g., in the case of these samples being placed within fruit punnets). The volatile test was adapted from Amat etal., Lett Appl Microbiol. 2017 Dec;65(6):489-495. Briefly, agar was inoculated with -IxlO5CFU / ml bacteria, and 10 mm agar plugs were cut out. These plugs were placed in close proximity (0.5 cm away) to the 4 x 4 cm sample containing either just PP or PP with the active component (KMB). The sample and bacteria were stored in a sealed petri dish (volume = 1030.6 cm2) for 24 hours. After the exposure period, the agar plugs were removed andsurviving bacteria were recovered, serially diluted, plated, grown at 37°C, and then counted to determine the CFU / cm2. Bacteria, when grown in this assay, were able to proliferate and be sustained for this 24-hour period, with controls growing ~108CFU / cm2. The volatiles released from the KMB containing samples were able to effectively kill bacteria over a 24-hour period, as shown in Figure 6 for S. aureus, indicating the release of antimicrobial gas from our materials.Food Shelf Life Test:

[0270] A food shelflife test was performed for grape packaging to evaluate the thick and thin film plastics’ ability to extend the shelf life of grapes packed in carbon dioxide modified atmosphere packaging.

[0271] The thick films and thin films were placed in the punnet under the grapes and plastic lids were adhered on top of the punnet in the presence of carbon dioxide. 35 replicates were used from each experimental group and 500 g punnets were stored at 20°C for 22 days. The grapes were checked for the evaluation every 2-3 days. At the end of 22 days, organoleptic properties were tested by a panel.

[0272] Tested samples include:Sample 1: 5% (w / w) Potassium metabisulfite (KMB) thick film (2 grams);Sample 2: 20% (w / w) KMB thin film (0.5 grams);Sample 3: Polypropylene (PP) film (control) (0.5 grams);Sample 4: 15% (w / w) KMB thin film (0.5 grams);Sample 5: 5% (w / w) KMB thin film (0.5 grams); andSample 6: 10% (w / w) KMB thin film (0.5 grams).Samples 1 and 2 here contained the same quantity of potassium metabisulfite in each film.

[0273] As shown in Figure 7, the best shelf life extension (from 14 to 22 days) was achieved for punnets #2, which used 20% (w / w) KMB thin film. Punnets #1 (5% KMB thick film) and #3 (PP film) were rejected before the 22-day period due to spoilage, preventing sensory evaluation of those samples. Punnets #2 showed the best overall performance, with 43% of the grapes remaining in good condition after 22 days. Punnets #4 (with 15% (w / w) KMB thin film) had the second-best result, with 17% of grapes still in good condition at 22 days.Table 9. Individual assessment of the panelists for sample #2 (20% (w / w) KMB thin film, Sample #4 (15% (w / w) KMB thin film), Sample #5 (5% (w / w) KMB thin film), and Sample #6 (10% (w / w) KMB thin film). Average values are shown below. The full results are shown in Figure 12.^Sample #2 External ^Overall s §Firmness Crunchiness: Texture: Sweetness: Acidity § Buy? § ^(20% KMB ^appearance Flavor: s *2.0 2.0 2.2 1.8 21.8 §:4Y / I \:thin film) £.2 p.2^Sample #4 ^External ^Overall §Firmness Crunchiness: Texture: Sweetness: Acidity5% KMB ^appearance flavor: & Y / 2N11.6 |1.6 2.0 12.0 1.8hhin film): T.6 h.8 | |^Sample #5 [External ^Overall §(Firmness Crunchiness: Texture: Sweetness: Acidity^(5% KMB ^appearance ^flavor: pY / 3N)1.4 1.4 1.6 1.6 1.6hin film): fi.6 I1-6I I^Sample #6 [External ^Overall §Firmness Crunchiness: Texture: Sweetness: Acidity^(10% KMB ^appearance flavor: & Y / 2N11.6 1.6 2.0 1.8 1.8hin film): T.8 h.8 | |0-RTM,l-Needs improvement, 2-Acceptable, 3-Exceeds expectation, 4-Excellent

[0274] Table 9 and Figure 12 shows the individual assessment of the panelist for 5-20% KMB thin film containing punnets. The scoring descriptions for values 0-4 are also given above. On Day 22, sensory evaluation was performed to assess organoleptic properties such as taste, texture, and overall quality. A tasting session was not conducted for PP film and 5% thick film samples containing punnets, which had already been discarded at that time point. External appearance, firmness, crunchiness, texture, sweetness, acidity, and overall flavor of the grape punnets #2 containing 20% KMB thin film samples ranged from 1.8-2.2. These grapes from punnets #2 were found to have the best overall flavor, indicating that the KMB containing thin film not only prevented mold but also maintained grape quality. The other punnets with lower concentration of KMB had slightly lower scores than 20% KMB thin film.Example 3: Potassium Metabisulfite is More Compatible with Plastic Carriers Than Sodium Metabisulfite

[0275] Methods: Powderized potassium metabisulfite (Sigma Aldrich, BioUltra, 97%) was combined with powderized polymer, extruded into pellets at temperatures up to 190°C, and heat pressed at a temperature of up to 170°C into a film for testing. All samples were tested for a bacterial contact time of 24 h following a modified ISO 22196 standard.Results

[0276] The antimicrobial efficacy of potassium metabisulfite in low-density polyethylene (LDPE, ExxonMobil 605B A) was assessed in the first set of experiments. As shown in Figures 8A-8B, all LDPE plastic carriers comprising potassium metabisulfite at a concentration of 0.5 wt%, 2.5 wt%, or 5 wt% caused an average of 6.5 log (>99.9999%) reduction of Staphylococcus aureus (S. aureus) and about 6 log (99.9999%) reduction of Escherichia coli (E. coli), almost completely inhibiting the growth for both bacteria.

[0277] The antimicrobial activity of potassium metabisulfite in PP (Impact Polypropylene, Sabie PHC31) was assessed in the second set of experiments. Production of PP -based plastic carrier requires a higher temperature that was expected to cause decomposition of potassium metabisulfite. Surprisingly, all PP -based plastic carriers comprising potassium metabisulfite at a concentration of 0.5 wt%, 1 wt%, 2 wt%, or 5 wt% still possessed high antimicrobial properties. As shown in Figure 9, even PP -based plastic carriers having the lowest concentration of potassium metabisulfite (0.5%) still caused almost 6 logs reduction of S. aureus. Controls used in the study included PP alone and a commercially available masterbatch loaded with 20% silver. These results demonstrate that potassium metabisulfite surprisingly retained its antimicrobial activity despite undergoing up to 190°C temperature during the manufacture of the PP -based plastic carriers.

[0278] The antimicrobial efficacy of potassium metabisulfite was compared with that of sodium metabisulfite (Sigma Aldrich, 97%) in the third set of experiments. Ethylene-vinyl acetate (EVA, ExxonMobil Escorene 00728CC) was used as the carrier for the antimicrobial at 20 wt% which was mixed with PP, diluting the active agent to final concentrations of 2 wt% and 5 wt%. As shown in Figures 10A-10B, sodium metabisulfite yielded no appreciable antibacterial effect against either S. aureus or E. coli., whereas potassium metabisulfite displayed very high antimicrobial activities, completely killing S. aureus at both concentrations.

[0279] Taken together, these results demonstrated that potassium metabisulfite is suitable for incorporation into plastics as an antimicrobial agent for various applications, including the use as safe, food-based additives / preservatives.Example 4: Monier-Williams sulfite test reports

[0280] Three Monier-Williams sulfite tests (001, 002 and 003) were run on Strawberries (test reports 001 and 002); and Bread Rolls (test report 003) to determine the sulfite level on control foods unlikely to be exposed to sulfites in SO2 (ppm). The composition used was 20% w / w KMB to LDPE.Monier-Williams sulfite test report - Report Number 001Date 22 / 08 / 2025Entry number 001Protocol notes and experiment summary

[0281] Protocol was followed without spike (the sample is exposed sulfite containing chemical called hydroxymethanesulfonate (HMS) for validation of the method).

[0282] The aim of the experiment was to assess the sulfite level on control foods unlikely to be exposed to sulfites. The response of the test will identify if the protocol is robust enough against external contaminants, or sulfites that may be present in the strawberry. The cause of any positive response will not be determined.

[0283] After sample 1, the lid of the trapping vessel was capped with parafilm to ensure any route into the trapping vessel is not the cause of the positive readings. The samples and titration results are shown in Table 10 and Table 11, below.Table 10. Sample detailsSample Substrate and Sulfite Storage Packaging Notes Number mass source conditions (Time typeand temperature)1 Strawberry Control Fresh from K37 vented Sainsburys source Sainsburys punnetStrawberry Control Fresh from K37 vented Sainsburys Sainsburys punnet sourced,Parafilmed lid on bubbling solutionTable 11. Titration resultsSample Replicates? Average titre Concentration ppm of SO2 Number (mL) (M) in sample1 1 0.1 0.0095 0.62 1 0.1 0.0095 0.6Conclusion

[0284] For a 2 hour reflux of standard untreated strawberries yielded a 0.6ppm content which is the smallest quantity of sulfites that are detectable at this level.Monier-Williams sulfite test report - Report Number 002Date 28 / 8 / 2025Entry number 002Protocol notes and experiment summary

[0285] Recovery of KMB and NaMB was not good, so HMS (hydroxymethanesulfonate) was used. Recovery was done for quality check of the experiment.

[0286] The Monier-Williams sulfite protocol version 1 was followed as it was outlined. The heating mantle thermocouple eroded after sample 1. So, sample 2 and 3 used a slightly different setup using a heating stirrer plate as opposed to a heating mantle. The samples and titration results are shown in Table 12 and Table 13, below.Table 12. Sample detailsSample Substrate and Sulfite source Storage conditions Packaging Notes Number mass (Time and typetemperature)1 Strawberry Spike HMS No storage K37 punnet, un Sainsbury's lOppm vented source 2 hour reflux 2 Strawberry Spike HMS No Storage K37 punnet, un Sainsbury's lOppm vented source 2 hour Reflux 3 Strawberry Spiked HMS No Storage K37 punnet, un Sainsbury's lOppm vented source 3 hour refluxTable 13. Titration resultsSample Replicates? Average titre Concentration of ppm of SO2 Number (mL) NaOH (M) in sample1 1 2.0 0.0068 8.72 1 1.3 0.01 8.33 1 1.5 0.01 9.6Conclusion

[0287] The recovery was significantly higher than previous attempts and was found to be best with a 3 hour reflux for the best recovery using HMS as the sulfite source. This will become the standard technique to validate recovery from a substrate.Monier-Williams sulfite test report - Report Number 003Date 29 / 08 / 2025Entry number 003Protocol notes and experiment summary

[0288] Following protocol 1.1 of the Monier Williams sulfite test, using the thermocouple in solution on the standard heater stirrer plate. 4x4 cm2 dimension is a standard sticker, as referred to in this Example.Table 14. Sample detailsSample Substrate and Sulfite source Storage conditions Packaging Notes Number mass (Time and typetemperature)1 Bread 120g bread 2 standard Ambient, 9 days K37 punnet, Sainsburys rolls stickers unvented source(Kingsmill)Table 15. Titration resultsSample Replicates? Average titre Concentration (M) ppm of SO2 Number (mL) in sample1 1 1.6 0.01 10.25Conclusion

[0289] Bread rolls when incorporated with 1 sticker per bread roll (60g) portion within a sealed PET punnet creates a detectable level of sulfite within the bread. The result sits on the labeling requirement level for the UK, EU and US regulatory bodies at 10.25ppm. This is likely the very maximum that can be included before labelling requirements are reached. There is a requirement to label a food product as having sulfites. That the level is approx lOppm SO2 in the food sample (food migration We want our carrier product to deliver SO2 at a certain release rate so that the food product has level of SO2 below this labelling threshold.Example 5 Comparison of NaMB with KMB

[0290] Microbiology data comparing KMB vs NaMB (both at 20% weight / weight) in LDPE. This Microbiology data shows the slower release of SO2 from KMB (compared to faster release of NaMB) in LDPE as after 6h contact time, the antimicrobial activity of KMB is high (full inhibition) while no meaningful activity remains for NaMB over this contact time.SO2 migration into food and sulfur burns

[0291] It is expected that there will be a greater migration of sodium metabisulfite into food since it liberates SO2 in a more uncontrolled way than the KMB design. There is a potential for sulfur burns to also be shown or be present.

[0292] Plastic sheets measuring 4 by 4cm by 300 micron are attached into the inside of a punnet or food container that is filled with a food substrate in likely case will be grapes or strawberries. The punnet is stored at food storage temperature (20C for grapes, 4C forstrawberries) for a duration of around 7-10 days (not fixed). During this time the food is visibly inspected for damages such as sulfur bums. Once estimated shelf life is achieved, the sulfite migration is measured using a Monier-Williams titration setup to establish ppm. It will measure significantly higher for a sodium metabisulfite laden material than potassium metabisulfite material.Material shelf life

[0293] It is expected that the shelf life of a product containing sodium metabisulfite is shorter due to uncontrolled release.

[0294] Stickers are aged at ambient temperature in the open atmosphere for 3 months. Afterward a biological spatial assay to determine antimicrobial effect will be performed to deduce the antimicrobial efficacy (see above details re indirect contact killing).Overview of testing

[0295] Antibacterial testing was conducted using an in-house non-contact exposure experiment against E. coli. A control containing the polymer only (LDPE film without the active ingredient) was used alongside the test samples for comparison purposes. Samples were incubated at 37°C for 6 hours. Surviving bacteria was recovered and plated on nutrient agar to determine the levels of growth or inhibition.Results

[0296] E. coli was tested against spent pressed samples of 20% NaMB in LDPE or 20% KMB in LDPE with non-contact exposure for 6 hours. The Log 10 growth inhibition of E. coli was calculated by subtracting the Log 10 CFU / mL recovered from the test samples from the LDPE only control. Following 6 hours exposure, 20% NaMB demonstrated a mean -1.23 log growth inhibition, meanwhile 20% KMB showed a mean -3.96 log growth inhibition.

[0297] Figure 13 shows: Antibacterial activity against E. coli following a 6 hour exposure period with 20% NaMB in LDPE and 20% KMB in LDPE. The mean+STD values of the Log 10 growth inhibition (CFU / mL) calculated from the LDPE only control are shown.Discussion

[0298] The testing of E. coli at 6 hours against spent 20% NaMB in LDPE and 20% KMB in LDPE samples in a spatial environment demonstrated a higher Log 10 growth inhibition for KMB. This difference is likely due to the faster release of SO2 from NaMB in comparison to KMB, therefore the antibacterial efficacy of KMB in LDPE lasts longer than that of NaMB within the same time frame. This work essentially shows that NaMB does not meaningfulantimicrobial properties after 6h contact time, whilst KMB does retain that activity. This is in line with the fast release of SO2 from NaMB compared to KMB which results in NaMB losing its efficacy much faster than KMB.

[0299] All documents, patents, patent applications, publications, product descriptions, and protocols which are cited throughout this application are incorporated herein by reference in their entireties for all purposes.

[0300] The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the disclosure. Modifications and variation of the above-described embodiments of the disclosure are possible without departing from the disclosure, as appreciated by those skilled in the art in light of the above teachings. It is therefore understood that, within the scope of the claims and their equivalents, the disclosure may be practiced otherwise than as specifically described.

Claims

CLAIMS:

1. A plastic carrier comprising about 0.1% (w / w) to about 50% (w / w) potassium metabisulfite based on the weight of the plastic carrier.

2. The plastic carrier of claim 1, comprising about 15% (w / w) to about 25% (w / w) potassium metabisulfite based on the weight of the plastic carrier.

3. The plastic carrier of claim 1 or 2, wherein at least a portion of the potassium metabisulfite is present on at least one surface of the plastic carrier or wherein at least a portion of the potassium metabisulfite is present in the bulk of the plastic carrier.

4. The plastic carrier of any one of claims 1-3, wherein the potassium metabisulfite is in a powdered form.

5. The plastic carrier of any one of claims 1-4, wherein the plastic carrier comprises granules comprising potassium metabisulfite.

6. The plastic carrier of claim 5, wherein the granules have an average size of about 1-200 pm or about 1-50 pm when measured using Malvern Laser Diffractometer.

7. The plastic carrier of claim 6, wherein the granules have a D90 size of about 20 to 30 pm when measured using a Malvern Laser Diffractometer, when added.

8. The plastic carrier of claim 6 or 7, wherein the granules have a D90 size of about 5 pm when measured using a Malvern Laser Diffractometer, in the formed carrier product.

9. The plastic carrier of any one of claims 1-8, wherein the plastic carrier has a pH of from about 6.5 to about 7.5.

10. The plastic carrier of any one of claims 1-9, wherein the plastic carrier emits an effective amount of sulfur dioxide (SO2).

11. The plastic carrier of any one of claims 1-10, wherein the potassium metabisulfite is not encapsulated in a metal oxide or silica.

12. The plastic carrier of any one of claims 1-11, wherein all or substantially all of the potassium metabisulfite is in direct contact with the plastic carrier.

13. The plastic carrier of any one of claims 1-12, wherein the plastic carrier is in the format of a film, a sticker, a fiber, a foam, a disc, a box, a lid, a punnet, or a container.

14. The plastic carrier of any one of claims 1-13, wherein a first surface of the plastic carrier comprises the potassium metabisulfite and the first surface comprises a surface area of at least 1 cm2.

15. The plastic carrier of claim 14, wherein the surface area of the first surface of the plastic carrier is 1 cm2to about 100 cm2.

16. The plastic carrier of claim 14 or 15, wherein the surface area of the first surface of the plastic carrier is no more than 50 cm2.

17. The plastic carrier of any one of claims 1-16, wherein the plastic carrier comprises thickness of between 100 pm and 1.5 mm.

18. The plastic carrier of any one of claims 1-17, wherein the plastic carrier comprises volume of between 1 cm3and 100 cm3.

19. The plastic carrier of any one of claims 1-18, wherein the plastic carrier has a surface-to-volume ratio ranging from 10 cm^(-1) to 5,000 cm^(-1).

20. The plastic carrier of any one of claims 1-19, wherein the plastic carrier further comprises a second surface and an adhesive material on the second surface of the plastic carrier.

21. The plastic carrier of any one of claims 1-20, wherein the plastic is a food grade plastic.

22. The plastic carrier of any one of claims 1-21, wherein the plastic is capable of injection molding at a temperature of up to 250°C.

23. The plastic carrier of any one of claims 1-22, wherein the plastic is capable of injection molding at a temperature of between 150°C and 250°C.

24. The plastic carrier of any one of claims 1-23, wherein the plastic is gas permeable.

25. The plastic carrier of any one of claims 1-24, wherein the plastic carrier comprises a plastic material selected from a polyolefin, polyester, acrylic or an ester derivative thereof, polyolefin elastomer, thermoplastic elastomer, elastomer, and combinations thereof.

26. The plastic carrier of claim 25, wherein the plastic material comprises a polyolefin, polyester, or copolymers thereof.

27. The plastic carrier of any one of claims 25-26, wherein the plastic material comprises a polyolefin, polyester, polyoxymethylene (POM), polyvinylidene fluoride (PVDF), polymethylmethacrylate (PMMA), polystyrene (PS), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), ethylene-vinyl acetate (EVA), ethylene methyl acrylate (EMA), polyvinyl alcohol (PVA), styrene acrylonitrile resin (SAN), or any combinations thereof.

28. The plastic carrier of any one of claims 25-27, wherein the plastic material comprises a polyethylene (PE) or polypropylene (PP).

29. The plastic carrier of claim 28, wherein the polyethylene comprises ultra-high molecular weight polyethylene (UHMWPE), high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), or low density polyethylene (LDPE).

30. The plastic carrier of claim 29, wherein the plastic material comprises LDPE.

31. The plastic carrier of claim 30, wherein the LDPE has an MFI of approx. 0.3 to 2.5, optionally 0.5.

32. The plastic carrier of any one of the preceding claims, wherein the carrier has an approx.4:1 ratio (20% w / w) of KMB to plastic material, optionally LPDE.

33. The plastic carrier of claim 32, wherein the potassium metabisulfite has a particle size of approximately between about 3 microns and about 7 microns, between about 4 microns and about 6 microns, between about 4.5 microns and about 5.5 microns or approx. 5 microns, in the formed carrier.

34. The plastic carrier of any one of the preceding claims, wherein the particle size is provided by jet milling.

35. The plastic carrier of any one of the preceding claims, having a combination of: an approx.4: 1 ratio (20% w / w) of KMB to plastic material; LDPE (optionally with an MFI of around 0.5); and a particle size of KMB of approx. 5 microns in the formed carrier.

36. The plastic carrier of any one of the preceding claims, wherein the plastic carrier is degradable.

37. The plastic carrier of claim 36, wherein the plastic carrier comprises polylactic acid (PLA), polycaprolactone (PCL), polyglycolide (PGA), or poly(lactide-co-glycolide) (PLGA).

38. The plastic carrier of any one of the preceding claims, wherein the plastic carrier extends shelflife of a food product by at least 3 days when measured at 20 °C.

39. The plastic carrier of claim 38, wherein the plastic carrier extends shelf life of a food product by 3-50 days when measured at 20 °C.

40. The plastic carrier of any one of claims 38-39, wherein the food product is a fruit, vegetable, meat or a baked good.

41. The plastic carrier of claim 40, wherein the fruit is strawberry, blueberry, raspberry, or grape.

42. The plastic carrier of any one of claims 38-41, wherein food migration of potassium metabisulfite is less than 0.01 mg / kg as measured using TES-AC-812, a contact time of 10 days, and temperature of 40 °C.

43. The plastic carrier of any one of claims 38-41, wherein food migration of SO2 is less than 0.001 mg / kg as measured using TES-AC-812, a contact time of 10 days, and temperature of 40 °C.

44. The plastic carrier of any one of claims 1-43, made by a process comprising steps of:(a) mixing (i) a masterbatch comprising a first plastic material and about 20% (w / w) to about 80% (w / w) potassium metabisulfite; and (ii) a second plastic material, to form a mixture; and(b) subjecting the mixture to a temperature of between 50 °C and 250 °C, to form the plastic carrier.

45. A method of manufacturing a plastic carrier, comprising:(a) mixing (i) a masterbatch comprising a first plastic material and about 20% (w / w) to about 80% (w / w) potassium metabisulfite; and (ii) a second plastic material, to form a mixture; and(b) subjecting the mixture to a temperature of between 50 °C and 250 °C, to form the plastic carrier.

46. The method of claim 45, wherein the method further comprises attaching the plastic carrier to a containing comprising a food product.

47. The plastic carrier of claim 44 or the method of any one of claims 45-46, wherein the temperature is between 150 and 190 °C.

48. The plastic carrier of claim 44 or the method of any one of claims 45-46, wherein the temperature is no more than 230 °C.

49. The plastic carrier or claim 44 or the method of any one of claims 44-48, wherein the method or process further comprises (c) applying an adhesive material to the surface of the plastic carrier.

50. The plastic carrier or claim 44 or the method of any one of claims 44-48, wherein the particle size is provided by jet milling.

51. A container comprising the plastic carrier of any one of claims 1-44 and 47-50.

52. The container of claim 51, wherein the container is a sealed container.

53. The container of claim 51 or 52, wherein the ratio of the exposed surface area of the plastic carrier and the volume of the interior of the container ranges from 0.001 cm-1to 0.5 cm-1.

54. The container of any one of claims 51-53, wherein the container has undergone modified atmosphere packaging.

55. The container of any one of claims 51-54, wherein the container comprises a fruit or vegetable in its interior.

56. The container of claim 55, wherein shelflife of the fruit or vegetable is extended by at least 3 days, compared to shelflife of the fruit or vegetable without the plastic carrier at 20 °C.

57. The container of claim 55, wherein shelf life of the fruit or vegetable is extended by 3-50 days at 20 °C, compared to shelf life of the fruit or vegetable without the plastic carrier at 20 °C.

58. The container of any one of claims 55-57, wherein the fruit is strawberry, blueberry, raspberry, or grape.

59. The container of any one of claims 51-58, wherein the plastic carrier is in the interior of the container.

60. A method of controlling or killing a microbe on a product, comprising (i) placing the plastic carrier of any one of claims 1-44 and 47-50 in proximity to the product or (ii) contacting the plastic carrier with the product.

61. The method of claim 60, wherein the plastic carrier is within 20 cm to the nearest surface of the product, and optionally wherein the product is a food product.

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