Thermoplastic compositions for biodegradable and compostable packaging intended for contact with food.

Abstract

In particular, a biodegradable and compostable food film having one or more layers is described, which is suitable for producing packaging that can extend the shelf life of fruits and vegetables.

Description

[Technical Field]

[0001] This paper describes a biodegradable and compostable thermoplastic composition intended for contact with food.

[0002] Furthermore, several suitable and possible embodiments of packaging made from biodegradable and compostable materials intended to come into contact with food are described.

[0003] In particular, flexible packaging (e.g., in the form of film, bags, or pouches) and rigid packaging (e.g., in the form of so-called clamshell containers) will be described.

[0004] The packaging described below is specifically intended for packaging and preserving fresh fruits and vegetables.

[0005] Such packaging can also be used for packaging and storing perishable fresh products other than fruits and vegetables, such as fresh floral products. [Background technology]

[0006] Preserving fresh fruits and vegetables during storage at the point of sale presents significant technical challenges.

[0007] The length of time that fruit and vegetable products can be stored without spoiling, and therefore the length of time they can remain on the shelves, is also known as "shelf life."

[0008] Various solutions are known that attempt to solve the problem of extending the shelf life of fresh fruits and vegetables.

[0009] For example, the use of packaging designed to absorb substances that accelerate the deterioration of fruits and vegetables, and / or packaging designed to release substances that have a positive effect on their shelf life, and / or packaging designed to positively interact with the packaged product, its atmosphere, or the microorganisms present therein is known.

[0010] Such packaging is also commercially known as "active packaging."

[0011] In particular, it is already known that packaging containing zeolite can be used to remove ethylene that accumulates inside the packaging following the processing of fruits and vegetables.

[0012] The packaging currently known for preserving fruits and vegetables is not entirely satisfactory. Spanish Utility Model No. 1,220,467 describes a film for packaging fruits and vegetables having at least three layers, with at least one layer containing zeolite to absorb ethylene released by fruits and vegetables during ripening, but this film is neither biodegradable nor compostable.

[0013] International Publication No. 2022 / 043441 describes a food packaging film material comprising three layers, in particular, one central layer made from a biodegradable polymer and two barrier layers positioned on either side to reduce the oxygen permeability of the film.

[0014] The two barrier layers are made of SiO x It is made from a polymer substrate on which silicon oxide (i.e., silicon oxide in which the oxygen content is not definitively determined), Al2O3 (aluminum oxide), or polyvinyl alcohol is arranged. International Publication No. 2022 / 043441 does not foresee the use of ethylene absorbents.

[0015] U.S. Patent No. 2001 / 0031299 describes an ethylene adsorbent comprising a silver-doped hydrophobic zeolite to improve ethylene absorption.

[0016] Spanish Patent Application Publication No. 2939544 describes a packaging film for fruits and vegetables having at least three layers, with zeolite (having the function of absorbing ethylene released during the ripening process of fruits or vegetables) added to one of the layers and a mixture of zinc oxide and silver ions (for limiting the growth of bacteria) added to another layer.

[0017] In some embodiments, the various layers of the film can be made from biodegradable polymers.

[0018] However, due to the high content of zinc oxide, the film described in Spanish Patent Application Publication No. 2939544 is not compostable. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0019] One of the inventors' aims is to at least partially solve the problems of the prior art, particularly the above problems.

[0020] In particular, one of the inventors' aims is to provide packaging for fruits and vegetables that is biodegradable and compostable.

[0021] Another aim of the inventors is to provide packaging for fruits and vegetables that can extend the shelf life of the stored products.

[0022] A further aim of the inventors is to provide packaging for fruits and vegetables that has appropriate transparency. [[ID=…]]

[0023] It is also an aim of the inventors to provide packaging for fruits and vegetables that has appropriate mechanical resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Hereinafter, several possible solutions for overcoming the drawbacks of the prior art will be described while referring to the accompanying drawings. It seems there is an incomplete tag reference in the original text. I've translated it as accurately as possible based on the provided content. If you have any further questions or need more clarification, please let me know.[Figure 1] Figure 1 shows some films suitable for packaging and preserving fresh fruits and vegetables. [Figure 2] Figure 2 shows a bag suitable for packaging and storing fresh fruits and vegetables, which can be obtained from the film in Figure 1. [Figure 3] Figure 3 shows a clamshell container (made by thermoforming) suitable for containing and preserving fresh fruits and vegetables. [Figure 4] Figure 4 shows some fresh strawberries as purchased. [Figure 5] Figures 5a to 5d show several strawberries after being stored in a refrigerator at 5°C for 3 days, packaged in four different types of bags, which will be described later. Figure 5e shows several strawberries after being stored in a refrigerator at 5°C for 3 days, packaged in the original packaging known in the art. [Figure 6] Figures 6b and 6d show the same strawberry samples as in Figures 5b and 5d after being stored in a refrigerator at 5°C for 7 days. Figure 6e shows the same strawberry samples as in Figure 5e after being stored in a refrigerator at 5°C for 5 days, but in their original packaging. [Figure 7] Figure 7 shows the same strawberry sample as in Figure 5d after being stored in a refrigerator at 5°C for 10 days. [Figure 8] Figure 8 shows the same strawberry sample as in Figure 5d after being stored in a refrigerator at 5°C for 12 days. [Modes for carrying out the invention]

[0025] Referring to the attached drawings, packaging in the form of a film is shown as reference no. 1, packaging in the form of a bag or sack (which can be obtained from film 1) is shown as reference no. 2, and packaging in the form of a so-called clamshell container with a lid is shown as reference no. 3.

[0026] The packaging 1, 2, and 3 shown in the attached drawings are made of biodegradable, compostable thermoplastic material intended for contact with food, which will be described in more detail later.

[0027] Film 1 can be used, for example, to wrap fruits and vegetables.

[0028] Bag 2 can be used, for example, to store fruits and vegetables.

[0029] The opening of bag 2 can be closed after inserting the fruits and vegetables, for example, by tying a knot, or simply by folding the edge back, or by a heat sealing means.

[0030] Clamshell container 3 can be used, for example, to store fruits and vegetables.

[0031] In one particular embodiment, packaging 1, 2, and 3 are single-layer packaging, that is, they are made of a single layer of thermoplastic material.

[0032] In particular, film 1 can be obtained by using conventional single-layer blown extrusion equipment and supplying a biodegradable and compostable thermoplastic material intended for contact with food in the form of pellets. The film can be processed into the form of a bag or sack, or into a substantially rigid container, such as a clamshell tray.

[0033] Conversely, bag 2 can be obtained by using conventional equipment for bag manufacturing and supplying film material such as tubular film (especially single-layer tubular film) or single-fold film (especially single-layer single-fold film).

[0034] The film-form material used to construct bag 2 is a biodegradable, compostable thermoplastic material intended for contact with food.

[0035] The clamshell container 3 can be obtained by using a conventional flat-head single-layer extrusion apparatus to supply a sheet of single-layer material obtained by feeding a biodegradable and compostable thermoplastic material intended for contact with food in the form of pellets, and then thermoforming the resulting sheet.

[0036] As will become clearer below, packaging 1, 2, and 3 are particularly advantageous for preserving products such as fresh fruits and fresh vegetables, significantly extending their shelf life.

[0037] As used herein, the adjective “thermoplastic” refers in particular to materials that can be molded under the action of heat, especially materials that can be processed through so-called blown extrusion or flat die extrusion.

[0038] As used herein, the term "pellet" generally refers to granular plastic material that is cylindrical or lenticular in shape and preferably has a maximum dimension of less than 5 mm.

[0039] The definition of "intended to come into contact with food" can be found in EC Regulation 1935 / 2004, which is referenced here.

[0040] As used herein, the adjective "biodegradable and compostable" means a material that, under certain temperature, humidity, and oxygen concentration conditions, can be converted into oxygen, carbon dioxide, and compost through the action of bacteria and microorganisms.

[0041] The term "compost" refers to a biologically stable, inert, and odorless organic substance that consists primarily of humic substances, active microorganisms, and trace elements, and can be used as fertilizer.

[0042] As used herein, the property of being "compostable" specifically refers to materials whose composition does not result in the release of heavy metals.

[0043] The term "compostable" as used and asserted herein also refers to materials that can be converted into compost even in the absence of ultraviolet light.

[0044] The definition of "biodegradable and compostable" materials is specified in the Italian technical standards UNI EN13432:2002 (Requirements for packaging recoverable by composting and biodegradation - test procedures) and UNI EN11451:2012 (Compostable and biodegradable bags for municipal solid waste collection - types, requirements and test procedures), which are unified at the European level.

[0045] For the definition of active packaging, please refer to EU Regulation 450 / 2009.

[0046] The composition of the pellets used to extrude the materials used in the production of packaging 1, 2, and 3 is: - A mixture of polyester polymers, or biodegradable and compostable thermoplastic polyester polymers, - Zeolite in a weight percentage of 0.1% to 60%, - Antimicrobial agents that are substantially and / or essentially free of metal-based compounds such as metals, metal oxides, and metal salts, Includes.

[0047] The zeolite and antimicrobial agent are dispersed in the polymer mass of the pellets, and therefore in the packaging materials 1, 2, and 3.

[0048] Zeolites present in polymer substrates play a particularly important role in counteracting processes that occur during the maturation phase, effectively slowing down the maturation of packaged products.

[0049] Preferably, the zeolite is present at a weight percentage of 0.1% to 10%, and more preferably at a weight percentage of 0.1% to 2%.

[0050] A zeolite content exceeding 2% by weight causes a decrease in the transparency of the material used to manufacture the packaging.

[0051] For example, to produce rigid, opaque containers, a higher proportion of zeolite can be used, and these containers can be fitted with a lid or sealing film made of a transparent composition.

[0052] In this specification, the term “antimicrobial” is intended to refer to biocide compounds that have the ability to inhibit the growth of bacteria and other microorganisms such as yeasts and molds that are naturally present on the surface of fruits and vegetables.

[0053] The antimicrobial compound or biocide is present in an amount of 0.02% to 10% by weight of the thermoplastic composition, preferably in an amount of 0.1% to 1.5% by weight.

[0054] The preferred biocide is citric acid.

[0055] It is preferable not to use citric acid in salt form.

[0056] The absorption of ethylene released by packaged products and the suppression of microbial growth create a synergistic effect in extending the shelf life of packaged fruits and vegetables.

[0057] In other words, surprisingly, it has been found that the combination of zeolite and biocides, particularly zeolite and citric acid, can extend the maturation time of food by at least 100% compared to conventional packaging, and by at least 100% compared to packaging using zeolite alone or biocides alone.

[0058] For example, the shelf life of a product, which is defined as the maturation time, or the number of days before it becomes unsaleable, has been experimentally confirmed to be extended up to four times, from 7 days to 28 days, in the case of mushrooms, as shown in Table 2 below.

[0059] The fact that the antimicrobial agent is substantially and / or essentially free of metal-based compounds such as metals or metal oxides and metal salts means that packaging 1,2,3 is suitable for contact with products intended for food consumption and is also compostable.

[0060] In particular, the antimicrobial agents used to produce packaging 1, 2, and 3 do not contain zinc oxide (ZnO), but zinc oxide is a compound that is relatively harmful to human health, and its presence also affects the possibility of composting the packaging.

[0061] A suitable biodegradable and compostable thermoplastic polyester for manufacturing packaging 1, 2, and 3 may be polybutylene-adipate-terephthalate (PBAT).

[0062] In possible embodiments, PBAT is present with a small amount of PLA (polylactic acid, a compostable polyester) to improve its extrudeability.

[0063] In other embodiments, the biodegradable and compostable thermoplastic polyester used to produce packaging 1, 2, and 3 may contain at least one thermoplastic polyhydroxyalkanoate (PHA).

[0064] Polyhydroxyalkanoates (PHAs) are a family of polymers (polyesters) composed of (R)-3-hydroxyalkanoates synthesized by bacteria through microbial fermentation processes.

[0065] PHAs can be synthesized as homopolymers (same monomer) or copolymers (different monomers) depending on the bacterial strain or growth substrate used.

[0066] Among PHA homopolymers is polyhydroxybutyrate (PHB).

[0067] PHAs are non-toxic, water-insoluble, biodegradable, compostable, and exhibit thermoplastic properties similar to petrochemical-derived plastics.

[0068] For example, poly-3-hydroxybutyrate (PHB) is the most widely studied PHA polymer and exhibits advanced crystalline properties similar to those of polypropylene.

[0069] Depending on the number of carbon atoms in the monomer, PHAs are called short-chain PHAs (scl-PHAs, 3-5 carbon atoms), medium-chain PHAs (mcl-PHAs, 6-15 carbon atoms), and long-chain PHAs.

[0070] The molecular weight of PHA can be varied depending on the intended use of the thermoplastic composition, being lower for molding and higher for extrusion (e.g., blown extrusion).

[0071] In a possible embodiment, the PHA used is 2 × 10 4 ~5×10 6 It has a molecular weight of Dalton.

[0072] It was found that adding PHB can improve the elasticity and compostability of the final product, particularly in the form of film.

[0073] In other embodiments, the biodegradable and compostable thermoplastic polyester used to produce packaging 1, 2, and 3 may include polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA).

[0074] The molecular weight of PBS can be in the range of 60,000 to 100,000 g / mol.

[0075] An example of PBS that can be used to extrude packaging 1, 2, and 3 is Mitsubishi FZ91, which has a fluidity (also called melt flow index or MFI) of 5 g / 10 min and a melting point of 115°C.

[0076] By using polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA), the transparency of packaging 1, 2, and 3 can be improved.

[0077] In particular, PBSA appears to be more amorphous and therefore more transparent.

[0078] In some embodiments, a mixture is used that includes a certain proportion of polylactic acid (PLA) in addition to one of the polymers discussed above, in order to improve the processability of the polymer mixture.

[0079] In one possible embodiment, the antimicrobial agent is composed of or includes citric acid, particularly in its anhydrous form.

[0080] Combining citric acid with zeolite significantly increases the shelf life of packaged fresh fruits and vegetables.

[0081] In the illustrated embodiment, citric acid is present at a weight percentage of 0.1% to 1.0% of the total weight of the polymer composition.

[0082] The inventors observed that when the weight percentage of citric acid was higher than 1%, it caused an excessive increase in the fluidity of the thermoplastic composition during the extrusion phase, making the material manufacturing process difficult.

[0083] It should also be noted that zeolite and citric acid not only do not affect the compostability of polymer materials, but both are also suitable for contact with food and skin.

[0084] Preferably, the zeolite is present at a weight percentage of 2%, and the citric acid is present at a weight percentage of 0.7%.

[0085] In other embodiments not shown, packaging 1, 2, and 3 can be multi-layer packaging.

[0086] For example, film 1 may comprise multiple layers of a biodegradable, compostable thermoplastic material intended for contact with food, each layer being compounded with zeolite and an antimicrobial agent, and substantially or essentially free from metals or metal-based compounds such as metal oxides and metal salts.

[0087] Preferably, the "antibacterial" compound is a biocide that is compatible with the thermoplastic polymer and is selected from benzoic acid, citric acid, sorbic acid, bacteriocins, biocides, essential oils having biocides (preferably selected from tea tree, lavender, thyme, onion, eucalyptus, and lemon essential oils), chitosan and chitin, polyphenols, graphene, terpenes, peptides, and cinnamaldehydes, or mixtures thereof.

[0088] It should be noted that the acids listed above are preferably used in their non-salt form.

[0089] The preferred compound is citric acid, which is available in solid or powder form.

[0090] Antimicrobial agents in the form of oils or other liquids are generally added to a carrier such as epoxidized soybean oil, which acts as a plasticizer, and then added to the polymer in a kneading extruder by known methods.

[0091] Layers intended to come into contact with fruits and vegetables are filled with, for example, zeolite and antimicrobial agents.

[0092] In multilayer embodiments, it is preferable to add zeolite and antibacterial agents to all layers.

[0093] By having more layers, the mechanical properties of the film 1, bag 2, and tray 3, particularly their tear strength, can be improved.

[0094] PHA, PBS, and PBSA all have the advantage of being heat-sealable and are therefore suitable for the manufacture of packaging in the form of bags.

[0095] Zeolite and citric acid have a particle size smaller than the thickness of the material being extruded.

[0096] The composition of the pellets, and therefore the compositions of packaging 1, 2, and 3, may contain starch, such as thermoplastic starch, in a weight percentage of 30% or less.

[0097] Adding starch helps reduce the manufacturing costs of packaging 1, 2, and 3, even if it results in reduced transparency of the packaging.

[0098] The pellet compositions used to produce packaging 1, 2, and 3 may contain a filler dispersant at a weight percentage of 1% or less in order to maintain a uniform distribution of zeolite and starch within the extruded product and obtain a material with a homogeneous composition.

[0099] As a dispersant, for example, a product sold as "4102" by the German company BYK can be used.

[0100] The pellet composition, and therefore the composition of packaging 1, 2, and 3, may contain food-grade plasticizers (e.g., epoxidized soybean oil, glycerin, water, sorbitol, or mixtures thereof) to improve extrudeability and the stretchability of the final product.

[0101] The weight percentage of plasticizer in the thermoplastic composition may be 0 to 15%.

[0102] Pellets having the composition described above can be obtained by weighing all components using a dedicated dispenser, or by injecting them in the case of liquid components using a known method, and then introducing them into a conventional extruder, such as a twin-screw extruder.

[0103] The extrusion temperature of the thermoplastic composition described above, i.e., the temperature at which film 1 is produced, is influenced by the polymer assumed by the type of machine used and the formulation.

[0104] For example, the extrusion temperature may be in the range of approximately 150°C to 180°C.

[0105] Taking into full consideration the thermal instability of the constituent components of the composition, a thermal melting profile is generally applied that allows for obtaining a molten material that is discharged to the outside at a temperature approximately 20°C higher than the melting point of the compound being processed.

[0106] In some alternative embodiments of the thermoplastic composition and packaging, the antimicrobial agent may include a mixture of citric acid and thyme oil.

[0107] Although thyme oil is more expensive than citric acid, it may be advantageous to add it because it possesses not only antibacterial properties but also antifungal properties.

[0108] In other embodiments, the thermoplastic composition includes sorbic acid in addition to citric acid because it has biocide and antifungal properties.

[0109] In one possible embodiment, the single-layer or multi-layer film material 1 has an average thickness of 7 to 20 μm, preferably about 12 to 20 μm, for example, about 13 μm.

[0110] If the thickness is less than 12 μm, film 1 may not be very durable.

[0111] On the other hand, thicknesses exceeding 20 μm become economically disadvantageous.

[0112] In one possible embodiment, the material of the clamshell container 3 has an average thickness in the range of 0.5 mm to 2.5 mm, preferably at least 1 mm.

[0113] In one possible embodiment, packaging 1, 2, 3 is packaging equipped with ventilation holes 4 (in the case of a clamshell container, at least the holes 4 can be located in the lid of the container).

[0114] The ventilation holes 4 provide significant permeability to packaging 1, 2, and 3 for gases (especially oxygen and carbon dioxide) and water vapor.

[0115] Ultimately, the ventilation holes 4 allow the atmosphere inside the packaging to be maintained at a level that minimizes anaerobic processes that deplete the freshness of the food.

[0116] The atmosphere inside the space defined by packaging 1, 2, and 3 can be altered by changing the shape, size, and number of ventilation holes 4.

[0117] The shape, size, and distribution of the ventilation holes 4 can be selected according to the type of product contained in packaging 1, 2, and 3, and the quantity of product packaged in packaging 1, 2, and 3.

[0118] In one possible embodiment, the ventilation opening 4 is substantially and / or essentially circular, having a diameter of 3 to 8 mm, preferably about 4 to 6 mm (i.e., about 12 mm). 2 ~approx. 28mm 2 (Having the cross-sectional area of ​​).

[0119] In particular, the ventilation opening 4 may have a diameter of approximately 6 mm.

[0120] For example, a 28 x 42 cm bag 2 has eight ventilation holes, four on each side or face of the bag.

[0121] Generally, 500cm 2 ~1200cm 2 Regarding the surface area, there are at least four pores of the type described above.

[0122] If there are no holes, the bag can be left open to allow for ventilation.

[0123] However, this technique cannot be repeated for a long time and is not suitable for obtaining the same effectiveness as the ventilation holes. The number of ventilation holes 4 depends on the size of the bag.

[0124] In one embodiment, the holes discussed above are on the surface of the package 1 cm 2 per hole area in mm 2 (hole area in mm 2 / surface in cm 2 ) and are present in a number that gives a ratio of 0.04 mm 2 / cm 2 to 0.4 mm 2 / cm 2 .

[0125] In fact, it has been found that ventilation holes 4 of this size and distribution significantly increase the shelf life of the fresh products stored in the bag 2.

[0126] The inventors have hypothesized that the dimensions of the ventilation holes 4 shown above enable more effective moisture discharge without affecting the effect on the maturation time of the product of the combination of zeolite and biocide.

[0127] In particular, it is considered that with the dimensions of the ventilation holes 4 shown above, the moisture created inside the package is less likely to block the ventilation holes and accumulate inside the package (this problem is significant when using conventional ventilation holes having a diameter of about 1.5 mm or less, for example).

[0128] The packages 1, 2, 3 thus produced have appropriate mechanical resistance and pose no risk to the health of consumers of the packaged fruits and vegetables.

[0129] Furthermore, the packages 1, 2, 3 appear to be easily biodegradable and compostable.

[0130] Furthermore, the packages 1, 2, 3 are substantially and / or essentially transparent, enabling visual inspection of the packaged fruits and vegetables.

[0131] The achievements of the inventors will be further explained with reference to the following examples.

[0132] <Example 1. Production of polymer film according to the present invention> In the extruder, to improve the distribution of zeolite and citric acid in the polymer mass, 0.2 kg of zeolite, 0.07 kg of citric acid, and 0.1 kg of filler dispersant were added to 10 kg of a mixture consisting of PBAT and PLA.

[0133] The filled polymer was blow-extruded and then converted into a film with a thickness of 13 μm.

[0134] <Example 2. Manufacturing of a transparent polymer film according to the present invention> In an extruder, 0.2 kg of zeolite, 0.07 kg of citric acid, and 0.1 kg of filler dispersant were added to 10 kg of PBSA.

[0135] The filled polymer was blow-extruded and then converted into a film with a thickness of 13 μm.

[0136] <Example 3. Strawberry Maturity Test> Using the film obtained in Example 1, a bag with dimensions of 18 × 28 cm was manufactured.

[0137] The bag had four holes on each side, each with a diameter of 6 mm.

[0138] Fresh strawberries were placed in roughly equal quantities, some in their original packaging and others inside the bags according to the present invention.

[0139] Strawberries packaged in the bag according to the present invention were placed in a first refrigerator set to a temperature of 5°C.

[0140] The strawberries, still in their original plastic packaging, were placed in a second refrigerator, which was identical to the first refrigerator and also set to a temperature of 5°C.

[0141] Samples were visually inspected and photographed daily to check for ripeness and the onset of early signs of wilting. A wilting fruit assessment meant that the fruit was not in a condition to be sold.

[0142] The condition of the strawberries in both samples on the start date of the test will be classified as "excellent".

[0143] Strawberries packaged in the bag according to the present invention maintained excellent condition until the 10th day and good condition until the 12th day, while strawberries in the original packaging showed the first signs of wilting as early as the 5th day and were confirmed to be wilted by the 7th day.

[0144] < Example 4. Comparative storage test of strawberries in the original packaging, additive-free bag packaging, bag packaging containing only zeolite, bag packaging containing only citric acid, and bag packaging containing zeolite and biocide according to the present invention. > To conduct comparative tests, bags measuring 18 x 28 cm with four 6 mm diameter holes on each side were prepared, and bags with the following compositions were prepared: a) A material consisting solely of the biodegradable and compostable thermoplastic polyester material described in Example 1 (the material does not contain additives, and in particular does not contain zeolite or citric acid). b) A biodegradable and compostable thermoplastic material as in Test a), containing the amount of zeolite shown in Example 1 but without citric acid. c) A biodegradable and compostable thermoplastic material as in Test a), which contains only the same amount of citric acid as in Example 1 but does not contain zeolite. d) Biodegradable and compostable thermoplastic material of Example 1

[0145] Samples a) to d) were formed by distributing equal amounts of the same type of fresh strawberries purchased on the same day into bags a) to d).

[0146] The original packaging of the strawberries was also retained as sample e). Both original packaging consisted of a polypropylene tray and film.

[0147] All packaging was kept in a refrigerator set to a temperature of 5°C.

[0148] Samples were visually inspected daily to check for signs of ripeness and wilting. A wilting fruit indicates that it is not in a marketable condition.

[0149] The condition of the strawberries at the start of the test is classified as "excellent."

[0150] In sample d), the strawberries packaged in the bag according to the present invention maintained excellent condition until the 12th day, while the strawberries in the additive-free bag (test a) had already wilted by the 5th day, and the strawberries in tests b), c), and e) wilted on the 7th day.

[0151] The strawberries from samples a) to e) exhibited the maturation behavior summarized in Table 1 below. In Table 1, na (not available) indicates that the sample was in an indistinguishable, very poor condition.

[0152] [Table 1]

[0153] The results of the comparative test showed that in test d), namely the maturation test in the packaging (bag) according to the present invention, the maturation time of strawberries increased from 5 days to 12 days.

[0154] In other words, strawberries can be stored effectively for at least nine days longer than in conventional polypropylene packaging as shown in test e), and remain in good or good condition (i.e., edible and sellable).

[0155] The same results were obtained when packaging bags made with comparative films using only zeolite (test b) and only citric acid (test c), demonstrating the synergistic effect produced by the presence of zeolite and biocide.

[0156] Furthermore, it is noteworthy that, when considering the purpose of preserving strawberries, the biodegradable and compostable polymer packaging (test a) performed worse than conventional polypropylene packaging (test e) under all other conditions.

[0157] <Example 5. Comparative test with other fruits and vegetables> Following Example 3, tests were also conducted on other vegetables to determine the extension of shelf life, i.e., maturation time.

[0158] The results are summarized in Table 2 below.

[0159] [Table 2]

[0160] As described above, the thermoplastic polymer composition of the present invention can be in the form of pellets, films, or containers with some degree of rigidity (closed with a lid or film).

[0161] The film has sufficient thickness (e.g., about 13 μm) and can be used to manufacture perforated bags for storing vegetables, especially fruits and vegetables.

[0162] Users can purchase bags and use them to store products that need to be kept separately.

[0163] Alternatively, as described above, the fruits and vegetables to be stored are packaged in packaging made of the composition of the present invention.

Claims

1. A package (1) having a biodegradable and compostable thermoplastic composition intended to come into contact with food, comprising one or more layers, a) At least one biodegradable and compostable thermoplastic polyester, b) Zeolite in a weight percentage of 0.04% to 60%, c) A substance and / or essentially free antimicrobial agent in an amount of 0.02% to 10% by weight, which is substantially and / or essentially free of metals or metal-based compounds. Packaging (1), including.

2. The packaging according to claim 1, wherein the zeolite is present in the thermoplastic composition at a weight percentage of 0.1% to 10%, more preferably 0.1% to 2.0%, and the antibacterial agent is present in the thermoplastic composition at a weight percentage of 0.1% to 1.5%.

3. The packaging according to claim 1 or 2, wherein the biodegradable and compostable thermoplastic polyester comprises at least one polymer, selected from polybutyrate-adipate-terephthalate (PBAT), thermoplastic polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), or polybutylene succinate adipate (PBSA).

4. The packaging according to any one of claims 1 to 3, wherein the antibacterial agent consists of or contains 0.1% to 1.0% citric acid by weight percentage.

5. The packaging according to any one of claims 1 to 4, further comprising 30% or less of starch by weight.

6. The packaging according to any one of claims 1 to 5, further comprising a filler dispersant in an amount of 1% or less by weight.

7. The packaging according to any one of claims 1 to 6, having a plurality of ventilation holes (4) suitable for enabling the exchange of gas and vapor, wherein the ventilation holes (4) have a diameter of 3 to 8 mm, preferably 4 to 6 mm.

8. The packaging according to any one of claims 1 to 7, further comprising a food-grade plasticizer in an amount of 15% or less by weight.

9. The packaging according to any one of claims 1 to 8, further comprising an antifungal agent.

10. The packaging according to any one of claims 1 to 9, characterized in that it is single-layer packaging or multi-layer packaging.

11. A biodegradable and compostable thermoplastic polymer composition intended for contact with food, a) At least one biodegradable and compostable thermoplastic polyester, b) Zeolite in a weight percentage of 0.04% to 60%, c) Antimicrobial agents that are substantially and / or essentially free of metals or metal-based compounds, A polymer composition comprising or containing the following.

12. The polymer composition according to claim 11, wherein the antimicrobial agent is a biocide compatible with the thermoplastic polymer composition, and is selected from benzoic acid, citric acid, sorbic acid, bacteriocins, biocides, essential oils (preferably selected from tea tree, lavender, thyme, onion, eucalyptus, and lemon essential oils), chitosan and chitin, polyphenols, graphene, terpenes, peptides, and cinnamaldehydes.

13. The polymer composition according to claim 11 or claim 12, wherein the antibacterial agent is 0.1% to 1.0% by weight of citric acid.

14. A polymer composition according to any one of claims 10 to 13, further comprising one of the properties of claims 2 to 10.

15. A method for delaying the maturation of vegetables, characterized in that the vegetables are packaged in the packaging described in any one of claims 1 to 10.

16. The use of a combination of zeolite and citric acid to delay the maturation of vegetables, preferably fruits, vegetables, mushrooms, and flowers.

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