Food Coating

Abstract

Disclosed herein are embodiments of coating compositions comprising cellulose nanomaterials and emulsion systems. The coating compositions can provide improved moisture barrier and wettability on fruit surfaces, control bioactivity, and improve the shelf life of food products, such as fruit, during ambient storage. Also disclosed herein are embodiments of dry and substantially dry coatings, films, and products produced with the coating compositions, as well as methods of producing and using the coating compositions described herein. [Selected Figure] Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of backdating to U.S. Provisional Application No. 62 / 452,897, filed January 31, 2017, which is incorporated herein by reference in its entirety.

[0002] Disclosed herein are embodiments of coating compositions and films for food products and methods of making and using the same. [Background technology]

[0003] Cavendish bananas (Musa acuminata) are a rich source of vitamins and bioactive compounds (e.g., dietary fiber and phenolic compounds) and are one of the most consumed fruits in the world. However, as a climatic fruit, bananas have a relatively short shelf life due to physiological disorders, postharvest diseases, and senescence. Bananas are an example of a food that typically requires external modification to maintain its shelf life. There remains a need in the art for improved compositions and coatings that can improve the shelf life and / or preharvest integrity of various food products, such as fresh produce, plants, and plant parts. Summary of the Invention

[0004] Disclosed herein are embodiments of coating compositions comprising a cellulose nanomaterial and an emulsion system comprising a hydrophobic material (e.g., a fatty acid) and a surfactant. The coating composition can further comprise a functional agent, a plasticizer, or any combination thereof. In some embodiments, the cellulose nanomaterial can comprise cellulose nanocrystals or cellulose nanofibrils.

[0005] Also disclosed herein are embodiments of a dry (or substantially dry) coating comprising a cellulose nanomaterial and a substantially water-free emulsion system comprising a hydrophobic material and a surfactant. In some embodiments, the coating composition or dry (or substantially dry) coating can be used to coat a food product, such as a plant or plant part.

[0006] Also disclosed herein are method embodiments that include coating or substantially coating a plant or plant part with an embodiment of the coating composition described herein.

[0007] The foregoing and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating the mechanism of action of different coating composition embodiments described herein and their effectiveness in slowing postharvest ethylene biosynthesis in bananas. [Figure 2A] This graph shows the effect of different coating compositions on chlorophyll degradation in bananas during a 10-day storage period at 25±2°C and 50±5% relative humidity. In the figure, "Control" represents an uncoated sample, and "Semp" represents a sample coated with a 1.2% solution of commercially available Semperfresh™. "CNC" represents a coating formed from a composition containing cellulose nanocrystals (0.2 wt%, wet weight basis), chitosan (2 wt%, wet weight basis), and glycerol (0.4 wt%, wet weight basis). "CNF" represents a coating formed from a composition containing cellulose nanofibrils (0·3 wt%, wet weight basis). Both compositions contain the following emulsion systems: Tween 80 only ("CNCA" and "CNFA"), Tween 80 and oleic acid ("CNCB" and "CNFB"), and sucrose fatty acid esters and oleic acid ("CNCC" and "CNFC"). [Figure 2B] This graph shows the effect of different coating compositions on banana weight loss during a 10-day storage period at 25±2°C and 50±5% relative humidity. In the figure, "Control" represents an uncoated sample, and "Semp" represents a sample coated with a 1.2% solution of commercially available Semperfresh™. "CNC" represents a coating formed from a composition containing cellulose nanocrystals (0.2 wt%, wet weight basis), chitosan (2 wt%, wet weight basis), and glycerol (0.4 wt%, wet weight basis). "CNF" represents a coating formed from a composition containing cellulose nanofibrils (0·3 wt%, wet weight basis). Both compositions contain the following emulsion systems: Tween 80 only ("CNCA" and "CNFA"), Tween 80 and oleic acid ("CNCB" and "CNFB"), and sucrose fatty acid esters and oleic acid ("CNCC" and "CNFC"). [Figure 2C] This graph shows the effect of different coating compositions on the marketability of bananas during a 10-day storage period at 25±2°C and 50±5% relative humidity. In the figure, "Control" represents an uncoated sample, and "Semp" represents a sample coated with a 1.2% solution of commercially available Semperfresh™. "CNC" represents a coating formed from a composition containing cellulose nanocrystals (0.2 wt%, wet weight basis), chitosan (2 wt%, wet weight basis), and glycerol (0.4 wt%, wet weight basis). "CNF" represents a coating formed from a composition containing cellulose nanofibrils (0·3 wt%, wet weight basis). Both compositions contain the following emulsion systems: Tween 80 only ("CNCA" and "CNFA"), Tween 80 and oleic acid ("CNCB" and "CNFB"), and sucrose fatty acid esters and oleic acid ("CNCC" and "CNFC"). [Figure 3A]1 is a bar graph showing a comparison of ethylene production between uncoated and coated bananas. Coated samples include a coating produced with Semperfresh™ ("Semperfresh-treated") or an embodiment of a cellulose nanofiber coating ("CNFC") produced with a composition including 0.3 wt. % (wet weight basis) CNF, 1 wt. % sucrose fatty acid ester, and 1 wt. % oleic acid (wet weight basis). Ethylene production was measured after 48 hours of storage of the bananas in 1.5 L jars. [Figure 3B] 1 is a bar graph showing a comparison of CO2 and O2 production between uncoated and coated bananas. Coated samples are shown, including a coating produced with Semperfresh™ ("Semperfresh-treated"), or coated samples of an embodiment of a cellulose nanofiber coating ("CNFC") produced with a composition including 0.3 wt% (wet weight basis) CNF, 1 wt% sucrose fatty acid ester, and 1 wt% oleic acid (wet weight basis). O2 and CO2 production values ​​were evaluated after 24 hours of storage of the bananas in 1.5 L jars. [Figure 3C] 1 is a graph showing ACC concentrations monitored over a 10-day storage period at 25±2°C and 50±5% relative humidity. Uncoated and coated bananas were evaluated. Shown are coated bananas containing a coating produced with Semperfresh™ ("Semperfresh-treated") or coated bananas with an embodiment of a cellulose nanofiber coating ("CNFC") produced with a composition including 0.3 wt% (wet weight basis) CNF, 1 wt% sucrose fatty acid ester, and 1 wt% oleic acid (wet weight basis). [Figure 3D]1 is a graph showing ACS activity monitored over a 10-day storage period at 25±2°C and 50±5% relative humidity. Uncoated and coated bananas were evaluated. Shown are coated bananas containing a coating produced with Semperfresh™ ("Semperfresh-treated") or coated bananas with an embodiment of a cellulose nanofiber coating ("CNFC") produced with a composition comprising 0.3 wt% (wet weight basis) CNF, 1 wt% sucrose esters, and 1 wt% oleic acid (wet weight basis). [Figure 4A] SEM images showing the surface morphology characteristics of uncoated bananas at two different resolutions: 100 μm (top image) and 5 μm (bottom image). [Figure 4B] Included are SEM images showing the surface morphology of bananas coated with 1.2% Semperfresh™ coating at two different resolutions: 100 μm (top image) and 5 μm (bottom image). [Figure 4C] Included are SEM images at two different resolutions (100 μm (top image) and 5 μm (bottom image)) showing the surface morphology characteristics of bananas coated with a coating formed from a CNFC coating composition containing 0.3 wt % (wet weight basis) CNF, 1 wt % sucrose fatty acid ester (wet weight basis), and 1 wt % oleic acid (wet weight basis). [Figure 5A] 1 is a photographic image showing a comparison of the appearance of uncoated bananas (left image), Semperfresh™ coated bananas (center image), and CNFC-coated bananas (right image) during a 10-day storage period at 25±2° C. and 50±5% relative humidity. The CNFC-coated bananas included a coating formed from a composition including 0.3 wt % (wet weight basis) CNF, 1 wt % sucrose fatty acid ester (wet weight basis), and 1 wt % oleic acid (wet weight basis). [Figure 5B]1 is a bar graph showing a comparison of the firmness of uncoated bananas, Semperfresh™ coated bananas, and CNFC-coated bananas over a 10-day storage period at 25±2° C. and 50±5% relative humidity. The CNFC-coated bananas included a coating formed from a composition including 0.3 wt % (wet weight basis) CNF, 1 wt % sucrose fatty acid ester (wet weight basis), and 1 wt % oleic acid (wet weight basis). [Figure 5C] 1 is a bar graph showing a comparison of soluble solids for uncoated bananas, Semperfresh™ coated bananas, and CNFC-coated bananas over a 10-day storage period at 25±2° C. and 50±5% relative humidity. The CNFC-coated bananas included a coating formed from a composition including 0.3 wt % (wet weight basis) CNF, 1 wt % sucrose fatty acid ester (wet weight basis), and 1 wt % oleic acid (wet weight basis). [Figure 5D] 1 is a bar graph showing a comparison of titratable acidity of uncoated bananas, Semperfresh™ coated bananas, and CNFC-coated bananas over a 10-day storage period at 25±2° C. and 50±5% relative humidity. The CNFC-coated bananas included a coating formed from a composition including 0.3 wt % (wet weight basis) CNF, 1 wt % sucrose fatty acid ester (wet weight basis), and 1 wt % oleic acid (wet weight basis). [Figure 6] Photographs are shown comparing the appearance, weight loss, and firmness of fruit without a coating ("control") and different fruit with a coating formed from a composition containing 0.3 wt. % (wet weight basis) CNF, 1 wt. % sucrose fatty acid ester (wet weight basis), and 1 wt. % oleic acid (wet weight basis) ("coated"). [Figure 7] 1 shows photographic images comparing the external appearance and internal morphology of mangoes after 12 days of storage. The mangoes were either uncoated ("uncoated sample") or coated with a coating formed from a composition comprising 0.3 wt. % (wet weight basis) CNF, 1 wt. % sucrose fatty acid ester (wet weight basis), and 1 wt. % oleic acid (wet weight basis) ("coated sample"). [Figure 8A]Photographs of patty-shaped fruit pulp separated by films formed using a cellulose nanomaterial composition are shown. The leftmost image is before storage and after one week of storage at 5-7°C. (The second image from the left uses a film containing only CNF, the third image from the left uses a film containing CNF modified with low molecular weight chitosan, and the rightmost image uses a film containing CNF and high molecular weight CNF.) [Figure 8B] 1 is a graph of water absorption as a function of film type, comparing a control film (CNF) with two different chitosan-modified films ("CNF-low molecular weight CH" and "CNF-high molecular weight CH"). DETAILED DESCRIPTION OF THE INVENTION

[0009] Terminology Overview The following explanations of terms are provided to adequately describe the present disclosure and to guide those skilled in the art in practicing the disclosure. As used herein, "comprising" means "including," and the singular forms "a" or "an" or "the" include plural references unless the context clearly indicates otherwise. The term "or" refers to one element of stated alternative elements or a combination of two or more elements unless the context clearly dictates otherwise.

[0010] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of this disclosure, suitable methods and materials are described below. The materials, methods, and examples are illustrative only and not intended to be limiting, unless otherwise indicated. Other features of the present disclosure will be apparent from the following detailed description and claims.

[0011] Unless otherwise indicated, all numerical values ​​expressing amounts, molecular weights, percentages of ingredients, temperatures, times, and the like, when used in the specification or claims, should be understood to be modified by the term "about." Thus, unless otherwise indicated, implicitly or explicitly, the numerical parameters described are approximations that may depend on the desired properties sought and / or the limits of detection under standard test conditions / methods. When directly and explicitly distinguishing an embodiment from the prior art that discusses it, the numerical values ​​of that embodiment are not approximations unless the word "about" is recited. Moreover, not all alternatives described herein are equivalents.

[0012] As used herein, the term "cellulose nanocrystal" refers to a cellulose-derived object composed of at least one elementary fibril that contains primarily crystalline and paracrystalline regions and does not exhibit branching or entanglement between the cellulose nanocrystals or between network-like structures.

[0013] As used herein, the term "cellulose nanofibril" refers to a cellulose-derived object composed of at least one elementary fibril that contains crystalline, paracrystalline, and amorphous regions and may exhibit longitudinal splits, entanglements between cellulose nanofibrils, or a network-like structure.

[0014] As used herein, the term "crosslinking" refers to the use of substances (molecules or ions) to join at least two molecules (whether the same or different) through chemical bonds such as covalent, ionic, and / or electrostatic bonds.

[0015] As used herein, the term "elementary fibril" or "fibril" refers to a cellulose-derived structure that arises from a single terminal enzyme complex and has a cellulose chain organization that is specific to each plant, animal, algae, and bacterial species.

[0016] As used herein, the term "encapsulation" refers to the formation of a barrier that completely or partially surrounds a particle or object to specifically control the migration of substances into or out of the encapsulated particle or object.

[0017] The term "exogenous" refers to any material that is present within or on an organism or living cell or tissue or object, but originates from outside the organism / cell / tissue / object, as opposed to something that is endogenous. As used herein, the exogenous synthetic films disclosed herein are distinguished from natural films or cuticles produced by plants or plant parts.

[0018] As used herein, the term "leaching" refers to the extraction of certain organic and inorganic materials from a plant or plant part into a liquid, such as a treatment composition or other suitable aqueous or non-aqueous composition.

[0019] As used herein, the term "mitigating" refers to the ability of the disclosed compositions, or dry (or substantially dry) coatings or films produced from the compositions, or methods using the disclosed compositions to substantially reduce (e.g., by 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%) the occurrence of pre-harvest or post-harvest damage. In some embodiments, pre-harvest or post-harvest damage can be caused by biotic stress, abiotic stress, storage, and / or treatment (e.g., heat treatment).

[0020] As used herein, the term "nanofiber" refers to a nano-object having two external dimensions on the nanoscale and a significantly larger third dimension.

[0021] As used herein, the term "nutrient" refers to any component found in a plant or plant part, whether naturally occurring or absorbed during growth. Nutrients can include, but are not limited to, macronutrients such as nitrogen, phosphorus, and potassium; macronutrients such as calcium, sulfur, and magnesium; and micronutrients or trace minerals such as boron, manganese, iron, zinc, copper, and nickel.

[0022] As used herein, the term "plant" refers to the entire plant, including any root structures, vascular bundles, vegetative tissue, and reproductive tissue. "Plant part" includes any part of a plant. For example, a plant part can be obtained upon harvesting of a plant. Plant parts encompassed by the present disclosure include, but are not limited to, flowers, fruits, seeds, leaves, vegetables, stems, roots, branches, and combinations thereof, which are less than the entire plant from which the plant part is derived.

[0023] As used herein, the term "prevent" refers to the ability of the disclosed compositions, or dry (or substantially dry) coatings or films produced from the compositions, or methods of using the disclosed compositions to completely or substantially prevent pre-harvest or post-harvest damage from occurring. In some embodiments, pre-harvest or post-harvest damage can be caused by biotic stress, abiotic stress, storage, and / or treatment (e.g., heat treatment).

[0024] As used herein, the term "UV damage" refers to any type of damage to an object described herein caused by UV rays. In some embodiments, such damage can include wilting, discoloration, shrinking, mottling, etc.

[0025] The term "stabilizer" refers to a compound that can improve the material properties, particularly the water resistance and mechanical properties of the dried (or substantially dried) coating or film produced from this coating composition, as well as the affinity between the cellulose nanomaterial and the inorganic salt component.

[0026] The amounts of components that can be used in the coating compositions are expressed as weight / weight percent on a wet weight basis unless otherwise indicated. When the components are in the form of or mixed as an aqueous solution, the amount of the component can be expressed as weight / volume percent (w / v%) or weight / weight percent (w / w%), which units are essentially the same.

[0027] Abbreviation CH Chitosan OA Oleic Acid SEFA sucrose fatty acid esters ACC 1-aminocyclopropane-1-carboxylic acid CNC cellulose nanocrystals CNF cellulose nanofiber ACS ACC synthase CNFC Chitosan-containing nanofiber CN cellulose nanomaterials CNCC Chitosan-containing Nano Calcium Carbonate NCC Nano Calcium Carbonate SEM Scanning Electron Microscopy

[0028] Introduction Several postharvest technologies, such as low temperature, edible coatings, and low-pressure and controlled-atmosphere storage, have been applied to delay fruit ripening and quality deterioration during postharvest storage. However, low-temperature storage can cause chilling injury and physiological damage to banana fruit, and low-pressure and controlled-atmosphere storage are capital-intensive and expensive. Edible coatings have been widely applied as a cost-effective, environmentally friendly postharvest technology for fruits and vegetables. Such coatings can create a modified atmosphere by creating a semipermeable barrier to oxygen, carbon dioxide, moisture, and solute transport.

[0029] While lipid- and / or hydrocolloid-based coatings have been utilized to extend the shelf life of various fruits, such as harvested bananas, several challenges exist that need to be addressed in the art, such as insufficient moisture and gas barrier and poor adhesion to fruit surfaces. This disclosure describes unique coating compositions, coatings, and films that help foodstuffs (e.g., packaged foods, plants, and plant parts) retain various properties (e.g., firmness, weight loss, etc.), thereby improving and maintaining the overall integrity and marketability of the foodstuffs. The disclosed compositions, coatings, and films comprise a unique combination of cellulose nanomaterials and an emulsion system that helps maintain this integrity and marketability.

[0030] Composition and Coating Embodiments Disclosed herein are embodiments of compositions that can be used to form coatings on the exterior surfaces of foodstuffs, such as packaged fresh produce, plants, or plant parts.

[0031] In some embodiments, the ingredients of the coating compositions described herein are edible, and in some instances, the ingredients have a regulatory status of Generally Recognized As Safe (GRAS) as determined by the U.S. Food and Drug Administration. In other instances, the ingredients are listed on the Environmental Protection Agency's Lists 4A and 4B as being environmentally safe.

[0032] Embodiments of the coating compositions described herein include cellulose nanomaterials. As used herein, cellulose nanomaterials are cellulosic materials composed primarily of linear chains of 100 to over 10,000 β-D-glucopyranose units joined by glucosidic bonds at the C1 and C4 positions of the cellulose nanomaterials, and having nanoscale external dimensions or, in some embodiments, nanoscale internal or surface structure. In some embodiments, cellulose nanomaterials can include cellulose nanofibrils (also referred to herein as "CNFs") or cellulose nanocrystals (also referred to herein as "CNCs"). In some independent embodiments, such nanomaterials can include some cellulose microcrystals or cellulose microfibrils. The amount of cellulose microcrystals or cellulose microfibrils present in such embodiments can be decreased or increased depending on the extraction method used to produce the cellulose nanomaterial and / or by modifying the cellulose-containing species from which these components are extracted. In some embodiments, the cellulose nanomaterial consists of cellulose nanofibrils or cellulose nanocrystals. Cellulose nanomaterials are typically selected to provide clear coatings and improved matrices for incorporating other materials / components disclosed herein.

[0033] The cellulose nanomaterials of the disclosed coating compositions are typically selected to have a structure and chemical properties suitable for use in a particular composition embodiment and for methods of using the compositions disclosed herein. For example, the cellulose nanomaterials are typically selected to provide acceptable, transparent, water-resistant coatings. In some embodiments, the cellulose nanomaterial structure and chemical properties are optimized to provide a type of cellulose nanomaterial that contains both crystalline and amorphous regions. In some embodiments, the cellulose nanomaterial can have dimensions ranging from 3 nm to 300 nm in width. In some embodiments, the cellulose nanomaterial can have a length ranging from 15 nm to 100,000 nm, e.g., from 50 nm to 100,000 nm, or from 100 nm to 10,000 nm, 100 nm to 5,000 nm, 100 nm to 2,500 nm, 100 nm to 2,000 nm, or 100 nm to 1,000 nm. In some embodiments, the cellulose nanomaterials disclosed herein can have aspect ratios reminiscent of elementary fibrils in plant cell walls. In some embodiments, the cellulose nanomaterials have aspect ratios (ratio of longest dimension to shortest dimension) in the range of 5 to 1000, e.g., 10 to 1000, or 20 to 1000, or 30 to 1000, or 50 to 1000. Exemplary cellulose nanomaterials with aspect ratios in this range are the cellulose nanofibril materials disclosed herein. In other embodiments, the cellulose nanomaterials can have aspect ratios in the range of 5 to 1000, e.g., 5 to 500, or 5 to 250, or 5 to 200, or 5 to 150, or 5 to 100. Exemplary cellulose nanomaterials with aspect ratios in this range are the cellulose nanocrystal materials disclosed herein. In certain disclosed embodiments, the cellulose nanomaterial may be cellulose nanofibrils that can be prepared using conventional methods known to those skilled in the art, taking advantage of the present disclosure, for example, by mechanical refining of cellulose derived from woody fibers or non-woody plant fibers, followed by fibrillation with or without chemical pretreatment.The methods used to prepare cellulose nanofibrils may or may not result in compositions of cellulose nanofibrils-containing residual hemicellulose. In some embodiments, cellulose nanofibrils may be purchased from commercial sources and then used in the compositions of the present disclosure.

[0034] Coating composition embodiments disclosed herein can further include an emulsion system, a functional additive, a plasticizer, or any combination thereof, and are typically aqueous compositions. In some embodiments, the emulsion system can include one or more hydrophobic materials (e.g., fatty acids), one or more surfactants, or a combination thereof. Emulsion system embodiments, functional additives, and plasticizers are described in more detail below. In certain disclosed embodiments, the coating composition comprises, consists essentially of, or consists of a cellulose nanomaterial, a functional additive (e.g., chitosan, aloe vera, potassium sorbate, ethylenediaminetetraacetic acid (EDTA), a quaternary ammonium salt, or any combination thereof), a plasticizer (e.g., glycerol, sorbitol, polyethylene glycol 400, or any combination thereof), and an emulsion system. In exemplary embodiments, the coating composition comprises, consists essentially of, or consists of cellulose nanocrystals, chitosan, glycerol, and an emulsion system. In yet further embodiments, the coating composition comprises, consists essentially of, or consists of a cellulose nanomaterial and an emulsion system. In exemplary embodiments, the coating composition comprises, consists essentially of, or consists of cellulose nanofibrils and an emulsion system. In "essentially consisting" embodiments, the coating composition can include ingredients other than those specified in such embodiments, but these additional ingredients do not adversely affect the coating properties (as determined by comparing a food product containing a coating produced from such a composition with a food product without the coating), for example, by decreasing the wettability of the coating on the food product, increasing discoloration, increasing weight loss, decreasing marketability, increasing ethylene production, decreasing O2 concentration, increasing CO2 concentration, or any combination thereof.Specific amounts of the components of the coating composition are set forth below; these amounts are expressed as percentages of the total composition, and unless otherwise specified, the percentages set forth below refer to weight ratios, determined on a wet weight basis.

[0035] Emulsion system embodiments disclosed herein can include, consist essentially of, or consist of one or more hydrophobic materials, one or more surfactants, or any combination thereof. In certain disclosed embodiments, the emulsion includes, consists essentially of, or consists of a surfactant and a hydrophobic material. In embodiments where an emulsion system "consists essentially of" one or more hydrophobic materials, one or more surfactants, or any combination thereof, the emulsion system does not include or is free of any components that are detrimental to the emulsion system (e.g., inhibit the emulsion system's ability to form emulsion droplets and / or other types of agglomerates). For example, an emulsion system "consisting essentially of" one or more hydrophobic materials, one or more surfactants, or any combination thereof does not include components that cause creaming, sedimentation, flocculation, coalescence, or separation of the emulsion system. In embodiments in which the emulsion system comprises a fatty acid and a surfactant, the surfactant is typically selected based on its ability to form hydrophobic droplets (or other types of aggregate structures), facilitate placement of the emulsion system in a hydrophobic cellulose nanomaterial matrix, and / or reduce the surface tension of the coating composition to improve the stability, uniformity, and spreadability of the emulsion coating.

[0036] In some embodiments, one or more hydrophobic components of the emulsion system may be an oil or a fatty acid. The oil may be, but is not limited to, an essential oil such as thyme oil, clove oil, oregano oil, lemongrass oil, marjoram oil, cinnamon oil, coriander oil, or any combination thereof; a vegetable oil; olive oil; avocado oil; palm oil; and any combination thereof. In certain disclosed embodiments, the fatty acid is a medium-chain fatty acid having an aliphatic tail containing 6 to 12 carbons (saturated or unsaturated) (e.g., capric acid and lauric acid); a long-chain fatty acid having an aliphatic tail containing 13 to 21 carbons (saturated or unsaturated) (e.g., oleic acid, linoleic acid, α-linolenic acid, palmitic acid, stearic acid, arachidic acid), or any combination thereof. In some embodiments, the one or more surfactants of the emulsion system can be selected from polysorbate surfactants (e.g., polyoxyethylene (20) sorbitan monolaurate, also known as "TWEEN 20"; or polyoxyethylene sorbitan (80) monolaurate, also known as "Tween 80"), sorbitan surfactants (e.g., sorbitan monolaurate, also known as "SPAN 20"; or sorbitan monooleate, also known as "SPAN 80"), sucrose fatty acid esters (e.g., sucrose fatty acid esters having 1 to 8 carbons in the fatty acid hydrocarbon chain (e.g., sucrose esters of propionic acid, butyric acid, valeric acid, caprylic acid, or unsaturated forms thereof)), or any combination thereof. In certain disclosed embodiments, the surfactant is Tween 80, SEFA, or a combination thereof. In exemplary embodiments, the emulsion system comprises, consists essentially of, or consists of TWEEN 80. In yet further embodiments, the emulsion system comprises, consists essentially of, or consists of TWEEN 80 and oleic acid. In yet further embodiments, the emulsion system comprises, consists essentially of, or consists of SEFA and oleic acid.

[0037] Additionally, in some embodiments, the coating composition can further comprise one or more additional ingredients, such as a stabilizer (e.g., but not limited to, a carboxy- or sulfate-containing polysaccharide selected from alginic acid, sodium alginate, cellulose, cellulose derivatives, pectin polysaccharides, carboxymethyl dextran, xanthan gum, carboxymethyl starch, hyaluronic acid, dextran sulfate, pentosan polysulfate, carrageenan, fucoidan, or any combination thereof), an inorganic salt (e.g., a sodium-containing salt, a potassium-containing salt, a calcium-containing salt, a magnesium-containing salt, a stannous salt, or any combination thereof), an acidic compound (e.g., ascorbic acid or other organic acid), or any combination thereof). In embodiments including such additional components, the stabilizer may be present in an amount ranging from 0.05% by weight (wet weight basis) to 2% by weight (wet weight basis), for example, from 0.05% by weight (wet weight basis) to 0.1% by weight (wet weight basis), or from 0.05% by weight (wet weight basis) to 0.75% by weight (wet weight basis), or from 0.05% by weight (wet weight basis) to 0.5% by weight (wet weight basis), or from 0.05% by weight (wet weight basis) to 0.25% by weight (wet weight basis). The inorganic salt may be present in an amount ranging from 0.05% by weight (wet weight basis) to 2% by weight (wet weight basis), such as from 0.05% by weight (wet weight basis) to 0.1% by weight (wet weight basis), or from 0.05% by weight (wet weight basis) to 0.75% by weight (wet weight basis), or from 0.05% by weight (wet weight basis) to 0.5% by weight (wet weight basis), or from 0.05% by weight (wet weight basis) to 0.25% by weight (wet weight basis). The acidic compound can be present in an amount ranging from 0.5% (wet weight basis) to 3% (wet weight basis), for example, from 0.5% (wet weight basis) to 2% (wet weight basis), or from 0.5% (wet weight basis) to 1.5% (wet weight basis), or from 0.5% (wet weight basis) to 1.0% (wet weight basis), or from 0.05% (wet weight basis) to 0.75% (wet weight basis). Such ingredients do not adversely affect the properties of the emulsion system or coating composition.

[0038] Coating compositions further comprising one or more agricultural agents selected from nutrients (e.g., fertilizers), growth stimulants, plant growth regulators, herbicides, fungicides, pesticides, or combinations thereof are also contemplated. Such compositions can be produced using any of the methods disclosed herein and can be applied to crops, trees, shrubs, vines, vegetable seedlings, ornamental and decorative plants (e.g., plants grown for their flowers (e.g., roses, carnations, lilies, etc.), or foliage plants (e.g., ivy, ferns, etc.). The amount of agricultural agent used in such coating compositions can be selected within the limits set forth in the EPA guidelines. One of ordinary skill in the art will recognize that such an amount can be determined by reviewing the EPA guidelines for the selected agricultural agent and selecting an amount within the lower and upper limits set forth in the guidelines. In some such embodiments, the agricultural agent is typically provided in an amount ranging from 1 ppm to 5,000 ppm, e.g., from 1 ppm to 4,000 ppm, from 1 ppm to 3,000 ppm, from 1 ppm to 2,000 ppm, or from 1 ppm to 1,000 ppm. One of ordinary skill in the art will readily recognize that amounts below the manufacturer's suggested application levels can also be used.

[0039] In some embodiments, the amounts of cellulose nanomaterial and emulsion system used in the coating composition are selected to provide a ratio of cellulose nanomaterial to emulsion system ranging from 1:1 to 1:20, e.g., 1:2 to 1:8, or 1:1 to 1:5. In certain disclosed embodiments, the cellulose nanomaterial is cellulose nanofibrils, and this material is included in the coating composition in an emulsion system in a ratio of 1:2 to 1:20 or 1:2 to 1:8. In other certain disclosed embodiments, the cellulose nanomaterial is cellulose crystals, and this material is included in the coating composition in an emulsion system in a ratio of 1:1 to 1:20 or 1:1 to 1:5.

[0040] In some embodiments, the amount of cellulose nanomaterial used in the coating composition ranges from 0.1 wt% (wet weight basis) to 1 wt% (wet weight basis), e.g., from 0.1 wt% (wet weight basis) to 0.75 wt% (wet weight basis), or from 0.1 wt% (wet weight basis) to 0.5 wt% (wet weight basis), or from 0.1 wt% (wet weight basis) to 0.4 wt% (wet weight basis), or from 0.1 wt% (wet weight basis) to 0.3 wt% (wet weight basis), or from 0.1 wt% (wet weight basis) to 0.2 wt% (wet weight basis). In certain exemplary embodiments, the amount of cellulose nanomaterial used in the coating composition is 0.1 wt% (wet weight basis), 0.2 wt% (wet weight basis), 0.3 wt% (wet weight basis), or 0.4 wt% (wet weight basis). In some embodiments, the amount of emulsion system used in the coating composition ranges from 0.03% (wet weight basis) to 4% (wet weight basis), for example, from 0.03% (wet weight basis) to 3.5% (wet weight basis), or from 0.03% (wet weight basis) to 3% (wet weight basis), or from 0.03% (wet weight basis) to 2.5% (wet weight basis), or from 0.03% (wet weight basis) to 2% (wet weight basis), or from 0.03% (wet weight basis) to 1.5% (wet weight basis), or from 0.03% (wet weight basis) to 1% (wet weight basis), or from 0.03% (wet weight basis) to 0.5% (wet weight basis).In such embodiments, the emulsion system can include one surfactant in such amounts, or the emulsion system can include a mixture of surfactant and hydrophobic material in such amounts, where the surfactant is present in the mixture in an amount ranging from 0.03% (wet weight basis) to 5% (wet weight basis) by weight (e.g., 0.03% (wet weight basis) to 2% (wet weight basis), or 0.03% (wet weight basis) to 1% (wet weight basis), or 0.2% (wet weight basis) to 1% (wet weight basis) by weight), and the hydrophobic material is The surfactant is present in the mixture in an amount ranging from 0.1 wt. % (wet weight basis) to 5 wt. % (wet weight basis) (e.g., 0.1 wt. % (wet weight basis) to 4 wt. % (wet weight basis), or 0.1 wt. % (wet weight basis) to 3 wt. % (wet weight basis), or 0.1 wt. % (wet weight basis) to 2 wt. % (wet weight basis), or 0.1 wt. % (wet weight basis) to 1.5 wt. % (wet weight basis), or 0.1 wt. % (wet weight basis) to 1 wt. % (wet weight basis)). In an exemplary embodiment, the emulsion system comprises a surfactant in an amount ranging from 0.0 wt. 3% by weight (wet weight basis), or 0.2% by weight (wet weight basis), or 1% by weight (wet weight basis), and / or 1% by weight (wet weight basis) of a hydrophobic material. In embodiments further comprising a functional additive and / or a plasticizer, the functional additive is present in a range of 0.1% by weight (wet weight basis) to 3% by weight (wet weight basis), for example, 0.1% by weight (wet weight basis) to 2.5% by weight (wet weight basis), or 0.1% by weight (wet weight basis) to 2% by weight (wet weight basis), or 0.1% by weight (wet weight basis) to 1.5% by weight (wet weight basis). The coating composition may be used in an amount ranging from 0.02 wt% (wet weight basis) to 1 wt% (wet weight basis), and the plasticizer may be present in an amount ranging from 0.02 wt% (wet weight basis) to 0.5 wt% (wet weight basis), or from 0.02 wt% (wet weight basis) to 0.4 wt% (wet weight basis), or from 0.02 wt% (wet weight basis) to 0.3 wt% (wet weight basis). Additional exemplary coating compositions and the amounts of components used in such compositions are also described in the Examples section and figures of this disclosure.

[0041] In one exemplary embodiment, a coating composition comprising cellulose nanofibrils and an emulsion system containing oleic acid and a sucrose fatty acid ester is effective in improving the postharvest storability of banana fruits by controlling their physiological activity during ambient storage, improving coating adhesion to the fruit surface. In some embodiments, the emulsion system improved the hydrophobicity, stability, and wettability of the coating on the fruit surface. Such coating compositions also slowed the ethylene biosynthetic pathway, reducing ethylene and CO2 production in the fruit and altering fruit surface morphology, resulting in more uniform coating coverage. Furthermore, such coating embodiments are effective in reducing chlorophyll degradation in banana peels, fruit weight loss, and firmness, thereby improving marketability and shelf life during ambient storage.

[0042] Also disclosed herein are coatings formed from embodiments of the coating compositions described herein. As used herein, the term "coating" refers to a layer of the composition formed on the exterior of a food product, such as a plant or plant part. The layer need not be of uniform thickness or completely homogeneous in composition. These coating compositions can be dried to form a dry (or substantially dry) coating, as described below. Also disclosed herein are film embodiments that can be made using the disclosed composition embodiments. Such film embodiments can be used as flexible packaging components (e.g., biodegradable boards, films, and wrapping) for various perishable foods, such as meats, seafood, and the like. Film embodiments are edible, thus preventing consumer concerns about food safety. In some embodiments, the films can be fibrous or crystalline and can form durable, inert, and water-resistant coatings over the coated object. In some embodiments, the films include cellulose nanomaterials and functional agents, such as chitosan.

[0043] A coating, dried (or substantially dried) coating, or film need not cover the entire object to which it is applied. In some embodiments, the coating or film can substantially cover the object. In such embodiments, the film or coating can cover 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the surface area of ​​the object. In other embodiments, the film or coating can completely cover the object, i.e., cover 100% of the object. In some embodiments, the film or coating can have a thickness that varies by 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the object.

[0044] Coatings and / or films produced from embodiments of the coating compositions of the present disclosure are highly water-resistant and strong. The coatings and films can provide water resistance and barrier properties while preserving the unique functionality of the non-cellulose components of the composition. The coatings and films described herein provide protection from water loss caused by transpiration and / or freeze-thaw-related drip loss and can improve water resistance and barrier properties while preserving the unique functionality of the non-cellulose components of the composition. In still further embodiments, the coatings and films exhibit enhanced adhesion between cellulose nanomaterials and hydrophobic surfaces (e.g., hydrophobic fruit surfaces).

[0045] When applied to a target surface of a plant, plant part, or other food product, the disclosed compositions form a strong external barrier after drying. The composition can be dried to form a dry (or substantially dry) coating by evaporating the water in the coating composition. In some embodiments, the coating is dried with heat to accelerate drying of the coating composition, thereby preventing or mitigating prolonged exposure to oxygen and light. After applying the composition to an object, temperatures ranging from 30°C to 35°C can be used to dry the composition. In some embodiments, after applying the coating composition to an object, the composition can be dried (at least partially) using hot air drying techniques. Such hot air drying techniques can use temperatures ranging from 60°C to 90°C for times ranging from 2 minutes to 10 minutes. Coatings produced using embodiments of the coating compositions disclosed herein reduce the loss of color appearance and physical integrity associated with the leaching of anthocyanins and other biological pigments (e.g., betalains), nutrients, and water-soluble compounds. Preventing moisture loss before and after harvesting in plants and food products is important to the marketability of the product. The compositions of the present disclosure and coatings formed from such compositions can be used to prevent such moisture loss in susceptible plants and other foodstuffs.

[0046] In certain disclosed embodiments, plants or plant parts comprising a coating made from a composition disclosed herein exhibit properties not exhibited by equivalent plants or plant parts that do not comprise such a coating (i.e., similar, unmodified plants or plant parts). For example, in some embodiments, plants or plant parts comprising a coating formed from a composition disclosed herein exhibit weight loss (e.g., a 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% reduction) after thawing compared to equivalent plants or plant parts that are not coated with the coating. In some embodiments, plants or plant parts comprising a coating formed from a composition disclosed herein exhibit reduced morphological abnormalities (e.g., a 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% reduction) compared to equivalent plants or plant parts that are not coated with the coating. In still other embodiments, plants or plant parts including a coating formed from the disclosed compositions exhibit less firmness loss (e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% less firmness loss) compared to an equivalent plant or plant part not coated with the coating.

[0047] Method Embodiments Disclosed herein are methods of making and using embodiments of the coating compositions described herein.

[0048] Embodiments of methods for making the disclosed compositions may include dispersing appropriate amounts of each composition component disclosed herein in water (which may have been deionized, purified, etc.). In some embodiments, the composition components may be added to water simultaneously. In other embodiments, the components may be added sequentially to the same aqueous solution. In still other embodiments, aqueous solutions of each component may be prepared separately and then mixed. Certain components do not need to be dispersed in water prior to mixing and may therefore be added undiluted to one or more solutions containing other components. As used herein, "mixing" can be achieved by any means known in the art. For example, mechanical stirring, agitation, or co-spraying of the components can be used to "mix" the components described herein. In certain disclosed embodiments, an emulsion system is first prepared separately from the cellulose nanomaterial and then mixed with the cellulose nanomaterial (which may be formulated with additional components described above, such as functional additives and / or plasticizers). In certain disclosed embodiments, the emulsion system is generated by suspending a surfactant in ambient temperature water at elevated temperatures (e.g., 70°C). In emulsion-based embodiments further comprising a hydrophobic material (e.g., a fatty acid), the hydrophobic material can be added to the surfactant solution followed by homogenization. In embodiments where the coating composition comprises a functional additive and / or a plasticizer, the functional additive can be pretreated (e.g., dissolved in an acidic solution) and then mixed with the plasticizer and / or cellulose nanomaterial.

[0049] Once each component is dispersed in water (whether together or separately), the solution is then homogenized using a homogenizer at low or high shear. The level of shear used can be modified depending on the type of coating composition being used. Typically, the solution is homogenized at ambient temperature for a suitable time to completely dissolve, disperse, and / or emulsify the components in water. The final composition can then be formulated for application to an object by soaking, spray coating, immersion, enrobing, or any other suitable technique, as disclosed herein. Additional exemplary methods for making coating compositions are described in the Examples section of this disclosure.

[0050] In some embodiments, the composition is not intended for immediate use, for example, when the composition is packaged for future sale. Such compositions are shelf-stable such that less than 20%, 30%, 40%, or 50% of the composition separates after 5, 10, 20, 30, or 60 days of storage. Longer storage periods are also anticipated. Those skilled in the art will recognize that methods for creating shelf-stable compositions can include selecting an appropriate stabilizer to be added to the composition.

[0051] The compositions disclosed herein can be used to prevent pre- and post-harvest damage to plants or their parts, thereby extending the shelf life and increasing marketability of fresh produce.The compositions can be used in food products to promote the storage and appearance of food, especially edible products.The coatings and / or films formed from the coating compositions disclosed herein can be easily removed before sale, can be easily peeled off by consumers, and can be safely ingested orally.

[0052] In some embodiments, the coating and treatment compositions disclosed herein can be used to reduce or prevent color and nutrient leaching from fruits and / or vegetables. The disclosed compositions are also useful as food coatings and in the preparation of frozen foods to prevent drip loss and maintain integrity during thawing. Foodstuffs experience significant moisture loss during the freezing and thawing process due to syneresis (i.e., moisture loss after thawing) and evaporation. Films formed from the compositions described herein can mitigate this moisture loss. For example, the disclosed compositions can be used to reduce moisture loss / gain of bakery products (e.g., cookies, pastries, and breads) and / or meats during storage (refrigerated or ambient storage). Some embodiments can be used to reduce moisture loss / gain and / or sticking of candies and other confectioneries during storage (refrigerated or ambient storage). In still other embodiments, the disclosed compositions can be used to reduce gas (e.g., O2 and CO2) exchange with ambient air or exposure of various foods or other organic materials to harmful gases (e.g., ethylene gas) during storage and shelf life.

[0053] The compositions disclosed herein can also be used in agricultural applications to protect plant parts (e.g., crop seeds), plants, and / or plantlets from biotic and / or abiotic stresses before and after harvest. In some embodiments, the compositions described herein can be used alone or in combination with one or more agricultural chemicals to inhibit biotic stresses, such as insect, nematode, and / or microbial infestation, and to resist abiotic stresses, such as environmental stress. Those skilled in the art will recognize that there are several methods that can be used to determine the reduction in infestation resulting from the application of the compositions described herein. For example, for microbial levels, cultures can be taken and the number of colony-forming units (CFU) determined and compared to plant parts (e.g., crop seeds), plants, and / or plantlets that have not been treated with the composition. Similarly, the number of insects or insect larvae can be counted, and plant parts (e.g., crop seeds), plants, and / or plantlets that have been treated with the compositions described herein can be compared to similar untreated plant parts (e.g., crop seeds), plants, and / or plantlets within the same landscape. Generally, treated plants exhibit 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% less microbial, larval, and / or insect infestation compared to control plant parts (e.g., crop seeds), plants, and / or plantlets.

[0054] In some instances, the coating compositions are used to prevent or reduce weight loss, mold growth, and / or loss of firmness. By way of example only, embodiments of the disclosed compositions can be used to prevent mold growth and / or morphological changes in plant parts (e.g., fruits), such as tropical fruits. Exemplary plant parts that can be coated with the coating compositions disclosed herein include, but are not limited to, avocado, cantaloupe, papaya, mango, honeydew melon, and the like.

[0055] The composition does not impart any significant odor or taste to food, and also provides a safe, apparently clear coating that prevents discoloration or other damage to fruit due to UV exposure. The film can also prevent moisture loss due to heat and / or sunlight.

[0056] Modifying the physical properties of biodegradable products, such as boards, films, and packaging, to provide, for example, increased resistance to degradation, improved barrier properties, and / or improved strength, is yet another application for films made from the compositions described herein. It is also contemplated that the films, dried (or substantially dried) coatings, and coating compositions provided herein can be used as protective surface treatments or coatings for durable materials, for example, to reduce or prevent damage during shipping and handling. The majority of flexible packaging materials in the food industry are petroleum-derived polymers. Their lack of sustainability and concerns about toxic residues reduce their appeal to consumers. Alternative natural materials (e.g., cellulose and chitosan) lack water resistance. The films disclosed herein can be used to provide coatings that address these limitations.

[0057] In certain disclosed embodiments, the coating composition can be applied to an object using any suitable method to partially or completely cover the object and form a coating after drying. For example, the object can be dipped into the coating composition. In other embodiments, the coating composition can be dripped or brushed onto the object. In still other embodiments, the coating composition can be sprayed onto the object, covering the object (partially or completely) with the coating. Alternatively, a mechanical applicator or brush can be used to cover (partially or completely) the object and then apply the coating composition to the object. In embodiments relating to compositions used to coat plants and / or plant parts, such as fruits and / or vegetables, the composition can be added to the object before or after harvesting. Suitable sprayers and enrobers will be recognized by those skilled in the art. In some embodiments, the coating method can be selected based on the viscosity of the coating composition. For example, if the coating composition is sticky and the object to be coated is a post-harvest product (e.g., a fruit or vegetable), a dipping or dripping application method is typically used. Pre-harvest application typically involves applying the coating to the plant or plant part thereof using a spraying method.

[0058] Various objects can be contacted with embodiments of the compositions disclosed herein, thereby providing improved products. In some embodiments, the object is a food product, such as a plant or plant part. Exemplary objects are fruits, particularly fruits having hydrophobic surfaces, and vegetables, particularly vegetables having hydrophobic surfaces.

[0059] Generally, objects containing coatings produced with the compositions contain the organisms described herein, but upon drying, the relative concentrations of the components change, for example, due to water loss from the composition. Thus, a dried (substantially dry) coating formed from a coating composition generally contains less water and a higher concentration / ratio of (non-evaporable) compositional components. A substantially dried coating may still contain low levels of moisture, e.g., greater than 0% to 10% moisture, or greater than 0% to 7% moisture, or greater than 0% to 5% moisture, or greater than 0% to 4% moisture, or greater than 0% to 3% moisture. Table 1 shows representative ranges of the amounts of components present in a substantially dried coating, expressed as wt % on a dry weight basis. In a representative example, a substantially dried coating may contain cellulose nanofibrils or cellulose nanocrystals, which may be present in an amount ranging from 4.5% (dry weight basis) to 9.8% (dry weight basis), e.g., from 5% (dry weight basis) to 8.0% (dry weight basis). In some embodiments, the dry weight basis of each component of the substantially dry coating can be calculated by the formula: (percentage of solids in the dry coating) x (percentage of the particular component) / (total percentage of all components in the wet composition). In some other embodiments, the dry weight basis of each component of the dry coating can be calculated as follows: W dry = some of the components / total of all components. By way of example only, in an exemplary embodiment where the concentration of cellulose nanofibrils ranges from 4.5% by weight (dry weight basis) to 9.3% by weight (dry weight basis), this range was obtained using this calculation (accounting for 5% moisture retained in the substantially dried coating): 95 x 1.0 / 21, and 95 x 0.1 / 1.02, respectively. In some embodiments, the object can include a dry or substantially dry coating having a thickness in the range of greater than 0 μm to 50 μm, e.g., 1 μm to 40 μm, or 1 μm to 30 μm.

[0060] [Table 1]

[0061] Overview of Some Embodiments Disclosed herein are embodiments of a coating composition comprising a cellulose nanomaterial in an amount ranging from 0.1 wt % (wet weight basis) to 1 wt % (wet weight basis) and an emulsion system comprising a fatty acid and a surfactant, wherein the fatty acid is present in an amount ranging from 0.1 wt % (wet weight basis) to 5 wt % (wet weight basis) and the surfactant is present in an amount ranging from 0.1 wt % (wet weight basis) to 2 wt % (wet weight basis).

[0062] In some embodiments, the cellulose nanomaterial comprises cellulose nanofibrils, which are present in an amount ranging from 0.1% (wet weight basis) to 0.5% (wet weight basis).

[0063] In some embodiments, the cellulose nanomaterial comprises cellulose nanocrystals, which are present in an amount ranging from 0.1% (wet weight basis) to 1% (wet weight basis).

[0064] In some or all of the above embodiments, the fatty acid is oleic acid, capric acid, lauric acid, linoleic acid, alpha-linolenic acid, palmitic acid, stearic acid, arachidic acid, and any combination thereof.

[0065] In some or all of the above embodiments, the surfactant is a sucrose fatty acid ester or a polysorbate surfactant.

[0066] In some or all of the above embodiments, the composition further comprises a functional agent, a plasticizer, or a combination thereof. In some embodiments, the functional agent is chitosan.

[0067] In some or all of the above embodiments, the plasticizer is glycerol.

[0068] In some or all of the above embodiments, the coating composition comprises a functional agent and a plasticizer, wherein the functional agent is present in an amount ranging from 0.1 wt % (wet weight basis) to 2 wt % (wet weight basis), and the plasticizer is present in an amount ranging from 0.02 wt % (wet weight basis) to 1 wt % (wet weight basis).

[0069] In some embodiments, the coating composition comprises cellulose nanomaterial in an amount ranging from 0.1 wt % (wet weight basis) to 1 wt % (wet weight basis) and an emulsion system comprising oleic acid and sucrose fatty acid ester, wherein the oleic acid is present in an amount ranging from 0.1 wt % (wet weight basis) to 5 wt % (wet weight basis) and the sucrose fatty acid ester is present in an amount ranging from 0.1 wt % (wet weight basis) to 2 wt % (wet weight basis).

[0070] In some embodiments, the cellulose nanomaterial comprises cellulose nanofibrils.

[0071] In some embodiments, the coating composition comprises a cellulose nanomaterial in an amount ranging from 0.1 wt % (wet weight basis) to 1 wt % (wet weight basis), an emulsion system comprising a polysorbate kingdom surfactant present in an amount ranging from 0.1 wt % (wet weight basis) to 2 wt % (wet weight basis), and a functional agent, a plasticizer, or a combination thereof.

[0072] In some embodiments, the cellulose nanomaterial comprises cellulose nanocrystals.

[0073] In some or all of the above embodiments, the functional agent is chitosan and the plasticizer is glycerol.

[0074] Also disclosed herein are embodiments of a substantially dry coating comprising a cellulose nanomaterial and an emulsion system comprising a fatty acid and a surfactant.

[0075] In some embodiments, the cellulose nanomaterial is present in an amount ranging from 4.5% by weight (dry weight basis) to 9.8% by weight (dry weight basis).

[0076] In some or all of the above embodiments, the fatty acid is present in an amount ranging from 9.5% by weight (dry weight basis) to 23% by weight (dry weight basis).

[0077] In some or all of the above embodiments, the surfactant is present in an amount ranging from 9.5% by weight (dry weight basis) to 9.8% by weight (dry weight basis).

[0078] In some or all of the above embodiments, the cellulose nanomaterial comprises cellulose nanofibrils.

[0079] In some or all of the above embodiments, the cellulose nanomaterial comprises cellulose nanocrystals. In some embodiments, the composition further comprises chitosan in an amount ranging from 9.5% (dry weight basis) to 9.8% (dry weight basis).

[0080] In some or all of the above embodiments, the composition further comprises glycerol in an amount ranging from 2% by weight (dry weight basis) to 4.7% by weight (dry weight basis).

[0081] Also disclosed herein are plant part embodiments that include a coating formed from a coating composition according to some or all of the above coating composition embodiments.

[0082] Also disclosed herein are plant part embodiments comprising a substantially dried coating according to some or all of the above dry coating embodiments.

[0083] In some or all of the above embodiments, the plant part is a tropical fruit.

[0084] In some or all of the above embodiments, the plant part is a banana, papaya, avocado, melon, or mango.

[0085] Also disclosed herein are method embodiments that include coating or substantially coating a plant or plant part with a coating composition that includes cellulose nanomaterial in an amount ranging from 0.1% (wet weight basis) to 1% (wet weight basis) by weight and an emulsion system that includes a fatty acid and a surfactant, wherein the fatty acid is present in an amount ranging from 0.1% (wet weight basis) to 5% (wet weight basis) by weight and the surfactant is present in an amount ranging from 0.1% (wet weight basis) to 2% (wet weight basis).

[0086] Example The following materials and methods may be useful in making and using various embodiments of the present disclosure.

[0087] material CNF and CNC, derived from softwood kraft pulp and with solids contents of 2.95% and 11.8%, respectively, were produced at the Process Development Center at the University of Maine (ME, USA). Chitosan (97% deacetylation, 149 kDa molecular weight) was purchased from Premix (Iceland), Tween 80 from Amresco (OH, USA), SEFA from TCI American (OR, USA), OA and glycerol from Alfa Aesar (MA, USA), and acetic acid from JT Baker (NJ, USA). 1-Aminocyclopropane-1-carboxylic acid (ACC) and N-(2-hydroxyethyl)piperazine-N'-3-propanesulfonic acid (EPPS) were purchased from Chem Impex International, Inc. (IL, USA), HgCl2 from MP biomedicals (CA, USA), pyridoxal phosphate from TCI American (OR, USA), dithiothreitol (DTT) from Sigma (MO, USA), and trichloroacetic acid (TCA) and NaOCl from JT Baker (NJ, USA).

[0088] Organic Cavendish bananas (Piura, Peru) at ripeness stage 2 (slightly yellowish green) with no visible defects were purchased on the day they arrived at a local supermarket (OR, USA) and coated on the same day.

[0089] Example 1 In this example, two nonionic surfactants, including Tween 80 and sucrose fatty acid esters (SEFA), were evaluated as surfactants in a representative coating composition. These surfactants have different hydrophilic head groups (carbohydrate for Tween 80 and ethoxylate for SEFA).

[0090] In this example, the cellulose nanomaterials included cellulose nanofibers (CNFs), which have high flexibility and absorbency, and cellulose nanocrystals (CNCs), which are highly rigid, rod-like structures with a negative surface charge. These can be combined with functional additives, such as chitosan, to provide a matrix. The ability of coating compositions containing these components to improve the storability of postharvest bananas by improving coating adhesion to the fruit surface, enhancing the coating's moisture barrier, controlling bioactivity, and / or modifying the fruit's surface morphology was evaluated.

[0091] Fruit adhesion, coating hydrophobicity, and extrinsic fruit quality parameters (e.g., chlorophyll degradation, weight loss, and fruit marketability) were evaluated, as well as the coating's effects on surface properties (e.g., critical surface tension and cell morphology of fruit skin) and fruit physiological activities (e.g., ethylene biosynthesis pathway and ethylene and CO2 production). Additionally, the coating's ability to improve fruit storage was evaluated by monitoring intrinsic fruit quality (e.g., starch degradation, firmness, soluble solids, and titratable acidity) during ambient storage of fruit.

[0092] The coating compositions were prepared on a wet weight basis (weight ratio), and the concentration range of each component was determined based on the applicant's preliminary testing (data not shown). Each coating matrix, containing 0.3% CNF and 0.2% CNC-reinforced chitosan (2%), was formulated with surfactants (Tween 80 or SEFA) and / or OA to yield six different emulsion coatings, as reported in Figure 1. (Referring to Figure 1, the surfactant types used to form the oleic acid (OA) emulsions included Tween 80 and sucrose fatty acid esters (SEFA); θ represents the contact angle of the reference liquid on the banana surface; γL is the surface tension of the reference liquid on the banana peel; and γc is the critical surface tension of the banana peel.) Emulsion systems with different surfactant types were first prepared as follows: 1% Tween 80 was suspended in water at ambient temperature, and then SEFA was dispersed at 70°C to improve water solubility. Then, 1% OA (1 wt%) was added to the surfactant solution and homogenized for 1 minute. A coating composition containing only Tween 80 (10 wt%, dry weight basis) was also prepared as a positive control. For the CNF-based emulsion coating compositions, 0.3% CNF was mixed with surfactants and / or OA (CNFA: 0.03% Tween 80 only, CNFB: 1% Tween 80 and 1% OA, and CNFC: 1% SEFA and 1% OA) and then homogenized for 1 min (Polytron PT10-35, Luzernerstrasse, Switzerland). For the CNC-reinforced chitosan emulsion coating compositions, 2 wt% chitosan was dissolved in 1 wt / vol% acetic acid solution and homogenized for 1 min with 0.2% CNC and 0.4% glycerol. The prepared coating compositions were mixed with surfactants and / or OA (CNCA: 0.2% Tween 80 only, CNFB: 1% Tween 80 and 1% OA, and CNFC: 1% SEFA and 1% OA), homogenized for 3 minutes, and then degassed using a homemade water-jet vacuum system.

[0093] Three different coating application methods (dipping, spraying, and immersion) were evaluated when applying the coating to the fruit surface, and no significant differences were observed in fruit storage stability. A brushing method was used to further improve coating spreadability across the fruit surface. To ensure uniform coating, each coating composition was manually applied to the bananas using a 25 mm wide paintbrush. The fruits were then dried under forced air for 1 hour. Uncoated and coated fruits were stored unpackaged under fluorescent light at ambient conditions (20 ± 2°C, 50 ± 5% RH) for 10 days. Fruit coated with Semperfresh™ (Semp, 1.2 wt%, Pace International, LLC, WA, USA) served as a positive control. Semperfresh™ is a commercially available coating product containing sucrose fatty acid esters, monoglycerides and diglycerides, and carboxymethylcellulose, and is used to coat various fruits and vegetables, including bananas.

[0094] Example 2 Coating performance is strongly influenced by the hydration of the coating formulation, which correlates with the surface properties of the fruit. To date, limited efforts have been made to understand the correlation between coating hydration and fruit surface. In this example, the contact angle (CA) of the coating formulation and the spreading coefficient (W) of the coating composition on the banana surface were analyzed. s ) was evaluated, as well as the surface tension (ST) of the coating composition to meet the surface tension (ST) of the banana surface to ensure sufficient adhesion of the coating on the banana surface.

[0095] The CA was determined using a video contact angle system (FTA32, First Ten Angstroms, Inc., USA) equipped with a surface contact angle meter. 10 μL of the coating composition was dropped onto the horizontal surface of a banana from a height of 10 mm. After 30 seconds, the CA was recorded for all samples, excluding the effect of dispersion time on spreadability. The ST of the coating composition was determined using an FTA model T10 (First Ten Angstroms, Portsmouth, VA) equipped with a Du Nuoy ring (CSC Scientific Co., Fairfax, VA). All data were collected within 5 minutes to reach a steady state of ST. The spreadability of the coating composition was calculated, and the adhesion coefficient (W a =γ SV +γ LV -γ SL , which affects diffusion) and the cohesion coefficient (W c =2γ LV , which affects the contraction) s =W a -W c )(in the formula γ SV , γ SL , and γ LV represents the solid-vapor, solid-liquid, and liquid-vapor interfacial tensions of the coating composition).

[0096] To ensure adequate and uniform adhesion of the coating composition to the coated fruit surface, the ST of the developed coating composition must be lower than or close to the critical ST (γC) of the fruit surface. The critical ST of the banana surface was determined by extrapolation from a Zisman plot constructed using water, formamide, and 1-methylnaphthalene as reference liquids. In some embodiments, the critical surface tension of the fruit surface depends on the texture and composition of the fruit.

[0097] Example 3 In this example, the contact angle (CA) of the coating composition and the WVP of the derived film were determined to measure hydrophobicity. The CA of the coating composition on a silicon wafer surface was determined using the same method as described above. The coatings were derived from the developed coating composition. Briefly, 60 mL of the coating composition was uniformly poured into a 150 mm diameter polystyrene Petri dish (Falcon, PA, USA) and allowed to dry at room temperature for 2 days. Prior to measurement, the derived coatings were conditioned at 25 °C and 50% RH in a self-assembly chamber (Versa, PA, USA) (Jung et al., 2016). The WVP of the coatings was measured using the cup method based on ASTM Standard E96-87 (ASTM 2000; Park & ​​Zhao, 2004). Each film sample (75 x 75 mm) was sealed with vacuum grease between a Plexiglas test cup (57 x 15 mm) filled with 11 mL of distilled (DI) water and its lid, and a rubber band was used to secure the sealing ring. The test cup assembly was stored in a self-assembly chamber at 25°C and 50% RH and weighed hourly for 6 hours. Data were recorded as the mean and standard deviation of three replicate experiments.

[0098] Example 4 In this example, the chlorophyll content, weight loss (%), and marketability (%) of banana peels from uncoated (control) and coated fruit samples were evaluated and used as a scientific basis for selecting a coating composition to improve fruit storage stability. Eighteen bananas were randomly assigned to three groups (six fruits per group), with one replicate per group and three replicates per treatment. The chlorophyll content of banana peels was measured using a DA meter (Sinteleia, Bolonga, Italy), and the percentage of chlorophyll degradation was recorded as the change in chlorophyll content from the initial chlorophyll content at different sampling times (days 1–10). The weight loss (%) of fruit was calculated by multiplying the weight change from the initial weight at different sampling times by 100. The marketability (%) of fruit was determined based on visual observation of brown spots on the banana peel; fruit was considered unmarketable if 20% of the peel was covered with brown spots. The number of marketable fruits at different sampling times (days 1–10) was then divided by the total number of fruits (18) per treatment and multiplied by 100 to calculate marketability (%).

[0099] Coating compositions containing cellulose nanofibrils, such as those containing CNF, oleic acid, and SEFA (e.g., the "CNFC" coating described in some figures), performed well based on the above-mentioned measured parameters. Such coatings were further validated by coating a series of fresh fruit. Uncoated and coated (CNFC and Semp) fruit were evaluated for starch degradation, firmness, titratable acidity (TA), and total soluble solids (TSS). Photographs of the fruit were taken at various sampling times (days 0, 3, 7, and 10) during the same storage conditions as in the above study. Pulp starch content was determined using an iodine staining method to estimate starch conversion to sugars as a result of fruit ripening. Freshly prepared iodine solution was prepared using 2.5 g / L iodine and 10 g / L potassium iodide. At each sampling time, a cut surface of each banana was immersed in the iodine solution for 5 seconds, and six randomly selected cut surfaces from six fruits per treatment were visually observed. Fruit firmness was determined using a texture analyzer (TA-XT2 Texture Analyzer, Texture Technologies Corp., NY, USA) by penetrating each banana with a P / 6 stainless steel cylindrical probe to a depth of 7 mm at a speed of 10 mm / s. Three measurements were performed at different locations on each fruit, with one replicate experiment per treatment. Mean values ​​and standard deviations were recorded for six replicate experiments. For TSS and TA, 40 g of banana pulp was mixed with 160 mL of distilled water using a blender (Proctor Silex, NACCO Industry Inc., VA, USA). The mixture was filtered using qualitative filter paper with 2.5 μm pore size (Whatman, GE Healthcare Bio-Sciences, PA, USA). The TSS of the filtrate was measured using a refractometer (RA250-HE, KEM, Tokyo, Japan). The filtrate was then titrated with 0.1N NaOH to pH 8.3 using a pH meter (Orion 410A, Fisher scientific, MA, USA) and a digital titrator (Brinkmann, TX, USA).TA was recorded as the equivalent percentage of malic acid as the predominant acid in ripe bananas. One measurement was made for each fruit in replicates per treatment, and the mean and standard deviation were recorded for six replicates.

[0100] Example 5 In this example, the fruit bioactivity and surface properties of uncoated and coated fruits were investigated to understand the mechanism of effective coating.

[0101] Banana respiration (O2 and CO2) and ethylene production were measured using a gas chromatograph (GC-2014, Greenhouse gas analyzer, Shimadzu, Japan) with a flame ionization detector (FID, ethylene and CO2) and a thermal conductivity detector (TCD, O2). Five bananas were randomly selected, weighed, and placed in 1.5 L airtight glass jars with lids holding 10 mm rubber septa for headspace gas sampling. They were then stored at ambient temperature (20 ± 2°C). After 24 h, O2 and CO2 production was monitored, but ethylene production was measured after 48 h due to the small amount produced. For each bottle, 1 mL of headspace gas was collected using a gas-tight syringe (Series A, Valco Instrument Co., USA) and then injected into a GC equipped with three types of packed columns (molecular sieve columns 80 / 100 HAYESEP D, 8 / 100 HAYESEP N, and 60 / 80 (Supelco, Bellefonte, PA, USA)). Helium was added as the carrier gas at a pressure of 350 kP and a flow rate of 21.19 mL / min. The temperatures of the syringe, column, and FID detector were 150 °C, 90 °C, and 250 °C, respectively. Standard gases for O2, CO2, and ethylene were purchased from Air Liquide (Scott™, PA, USA), and the amounts of O2, CO2, and ethylene were calculated using GC solution software (Shimadzu, Japan).

[0102] By creating modified atmosphere conditions, the coating can affect the ethylene biosynthesis pathway in fruit, as illustrated in Figure 1. ACC was measured as a precursor of ethylene, and ACS activity was measured as the enzyme that catalyzes the synthesis of ACC from S-adenosylmethionine (SAM).

[0103] To measure ACC and ACS, banana pulp samples were collected at different sampling times (days 0, 3, 7, and 10) and stored at -80°C prior to analysis. To extract ACC, 2 g of freshly thawed banana pulp was homogenized in 10 mL of 9% TCA for 60 seconds and then incubated at 4°C for 24 hours. The extract was centrifuged at 10,000 × g for 30 minutes, and the supernatant was adjusted to pH 7–8 with 1 N NaOH. Two sample reaction mixtures were prepared in capped 10 mL vials: 500 μL of supernatant, 100 μL of 10 mM HgCl2, and 300 μL of distilled water. One of the samples was spiked with the internal standard ACC (50 μL of 0.05 mM ACC). For the hydrolysis of ACC to ethylene, 100 μL of saturated NaOH and 5.25% NaOCl were added to both mixtures and then incubated at 4 °C for 3 min. A 5 mL gas sample was then taken for ethylene measurement and quantified using GC. ACC concentrations were expressed as pmol / g fresh sample.

[0104] To measure ACS, 5 g of freshly thawed banana pulp was homogenized for 60 seconds in 10 mL of a buffer solution containing 100 mM N-(2-hydroxyethyl)piperazine-N'-3-propanesulfonic acid (EPPS), 0.5 μM pyridoxal phosphate, and 4 mM dithiothreitol (DTT), adjusted to pH 8.5 with KOH. The extract was centrifuged at 10,000 × g for 30 minutes, and the supernatant was then dialyzed overnight at 4°C in a dialysis buffer containing 2 mM EPPS, 0.2 μM pyridoxal phosphate, and 0.1 mM DTT. Similarly, two reaction mixtures containing 400 μL of enzyme solution, 50 μL of 600 mM EPPS (pH 8.5), and 90 μL of distilled water were prepared in 10 mL capped vials. One of the mixtures was spiked with the internal standard ACC (50 μL of 0.05 mM ACC). After adding 60 μL of 0.5 mM SMA, both reaction mixtures were incubated at 30 °C for 3 h and then mixed with 100 μL of 10 mM HgCl2 and 200 μL of distilled water. Finally, the reaction mixtures were hydrolyzed by adding 100 μL of saturated NaOH and 5.25% NaOCl. After incubation at 4 °C for 3 min, 5 mL of headspace gas was collected and ethylene production was measured using GC. ACS activity was expressed as pmol ethylene / g fresh sample.

[0105] Example 6 In this example, the effect of coating on the surface morphology of bananas was evaluated using a scanning electron microscope (SEM) (FEI Quanta 600, Cressington Scientific Instruments Ltd., UK). Uncoated, Semp-coated, and CNFC-coated banana peels were cut into 5 mm pieces and placed in modified Karnovsky's fixative for 2 h. The samples were rinsed in 0.1 M sodium cacodylate buffer and dehydrated in a graded series of acetone (10%, 30%, 50%, 70%, 90%, 95%, and 100% acetone) for 10–15 min each. The samples were dried in an EMS850 critical point dryer, mounted peel-side up on SEM stubs, and coated with gold and palladium. Digital images were acquired at an accelerating voltage of 5 kV.

[0106] To analyze the performance of coating compositions and derived coatings, a completely randomized two-factorial design was applied, considering two treatment factors (type of coating matrix: CNF and CNC-reinforced chitosan; type of emulsion: Tween 80 only, Tween 80 and OA, and SEFA and OA). PROC GLM was used to identify significant differences and interactions between each factor using the SAS program (SAS version 9.2, The SAS Institute, USA), and post-hoc least significant difference (LSD) was used for multiple comparisons. All measurements were performed in triplicate, and results were considered significantly different at P < 0.05.

[0107] A completely randomized design with a single treatment factor (type of coating composition: uncoated, Semp-coated, and CNFC-coated) was then applied to further investigate the internal fruit quality, bioactivity, and surface properties of bananas. All measurements were performed in either duplicate or triplicate. One-way analysis of variance was performed to determine significant differences between treatments, and post-hoc LSD was performed using statistical software (SAS version 9.2, The SAS Institute, USA). Results were considered significantly different at P<0.05.

[0108] [Table 2]

[0109] Example 7 The effectiveness of fruit coatings to reduce moisture loss and control postharvest respiration depends on the sufficient wetting and adhesion of the coating composition to the fruit surface and the hydrophobicity of the resulting coating. In this example, the wetting and hydrophobicity of the coating composition were evaluated by measuring the wettability (contact angle and spreading coefficient) of the coating composition on the fruit surface and the correlation between the surface tension (ST) of the coating composition and the critical ST of the fruit surface, the hydrophobicity (contact angle) of the coating composition on a hydrophobic silica wafer, and the WVP of the resulting coating.

[0110] The type of emulsion contained in the coating composition significantly (P<0.05) affected the CA of the banana surface, with the coating compositions containing OA / Tween 80 (36.8°) or OA / SEFA (31.2°) showing a lower CA than the coating composition containing OA / Tween 80 alone (44.8°) (Table 2). The diffusion coefficient (W s ) was significantly (P<0.05) influenced by the interaction between the type of coating matrix and the type of emulsion, with W being higher in the emulsified coating compositions (CNCB, CNCC, CNFB, and CNFC) than in the emulsion-free coating compositions (CNCA and CNFA). s The ST values ​​were high. The two treatment factors (coating matrix and emulsion) significantly (P < 0.05) interacted to affect the ST values ​​of the coating compositions, with the CNCC and CNFC coating compositions showing the lowest ST values ​​(26.0 mM / m and 25.4 mM / m, respectively) among all treatments (Table 2). These results confirm that the emulsion coating composition improved the wettability of the coating to the hydrophobic banana surface, which is composed of cutin and wax in the cell wall. In addition, the ST values ​​of the developed coating composition were lower than the critical ST values ​​of the fruit surface (derived from the Zisman plot), at 35.2 mN / m (Figure 1), indicating the low surface energy of the banana surface (<100 mN / m). Many fruit surfaces have low surface tension due to the presence of a natural wax layer. Because this natural wax layer protects the fruit, high wettability may be required for the uniform deposition of water-soluble coatings on the fruit surface. To improve the wetting of the coating on the fruit surface, the ST of the coating composition needs to be close to and / or lower than the critical ST of the fruit surface. The above results confirmed that all the coating compositions developed from this example, except for CNFA, ​​have ST lower than the critical ST of the banana surface, thus ensuring sufficient adhesion of the coating to the banana surface.

[0111] Regarding hydrophobicity, the coating composition containing OA / SEFA had significantly (P<0.05) lower CA on hydrophobic silicon wafers than the coating composition containing OA / Tween 80 (Table 2). This may be due to the more hydrophobic nature of SEFA compared to Tween 80, thereby lowering the oil-water interfacial tension and improving the hydrophobicity of the coating. Meanwhile, the type of coating matrix and emulsion contained had a significant (P<0.05) effect on the WVP of the derived coatings, with the CNFC film (0.03 g mL / m² d Pa) having the lowest WVP among all coating compositions and demonstrating an excellent moisture barrier (Table 2). Without being limited to a single theory, it is currently believed that the OA / SEFA emulsion system, compared to the CNC-reinforced chitosan coating, is able to be well dispersed in a continuous CNF phase with a slight surface charge and flexible structure, thus hindering water diffusion through the hydrophobic CNF emulsion matrix. The CNC-reinforced chitosan matrix may have a low compatibility with the OA / SEFA emulsion system, as indicated by the electrostatic interaction between the positively charged chitosan and the negative surface charge of the CNCs and the reduced surface charge due to the highly crystalline continuous phase. Therefore, an emulsion system composed of OA and SEFA in a CNF-based coating matrix can yield a hydrophobic coating with improved moisture barrier properties.

[0112] Example 8 The effects of the coating compositions on chlorophyll degradation, weight loss, and marketability of bananas during 10 days of ambient storage are reported in Figures 2A–2C. The CNFC coating resulted in the least and slowest chlorophyll degradation of banana peels among all coating compositions (Figure 2A). Furthermore, the CNFC coating resulted in the least weight loss (approximately 17%) at the end of 10 days of ambient storage compared to the uncoated treatment (approximately 24%) and the other treatments (approximately 19–23%) (Figure 2B). Furthermore, CNFC retained the highest marketability of the fruit over the storage period compared to the other coating compositions (Figure 2C). After 5 days of storage, uncoated (control) fruit lost approximately 50% of its marketability, whereas CNFC-coated fruit remained approximately 90% marketable even after 8 days of storage. Without being limited to a single theory, it is currently believed that the effectiveness of the CNFC coating may be attributed to the well-dispersed OA / SEFA emulsion system in the CNF coating matrix, which intimately interacts with the fruit surface, resulting in uniform coating coverage and a good moisture barrier, thus preventing moisture loss, reducing chlorophyll degradation, and improving the marketability of the fruit during storage.

[0113] Example 9 In this example, we further investigated the effects of uncoated, Semp-coated, and CNFC-coated bananas on their physiological activity (Figures 3A-3D) and surface properties (Figures 4A-4C) during ambient storage. Ethylene production in CNFC-coated fruits was significantly reduced (0.82 ppm / g) compared to uncoated fruits (4.41 ppm / g) and Semp-coated fruits (2.38 ppm / g) (Figure 3A). Furthermore, CNFC-coated fruits contained less CO and more O than uncoated fruits, but similar CO and O concentrations compared to Semp-coated fruits (Figure 3B). Fruit respiration (O and CO) and ethylene production are key physiological indicators for tracking changes in ripening and senescence over storage periods. These data confirmed that CNFC coating inhibits banana respiration and ethylene production by creating an altered internal atmosphere within the fruit, thereby delaying fruit ripening and senescence.

[0114] Postharvest, climacteric fruits produce ethylene through autocatalytic ethylene biosynthesis, where ACC is the precursor of ethylene and ACS is the catalytic enzyme that synthesizes ACC from SAM (Figure 1). As shown in Figure 3C, CNFC-coated fruits resulted in significantly higher ACC concentrations in the fruit compared with uncoated and Semp-coated fruits. This result indicated that the CNFC-coated fruit altered the internal atmosphere of the fruit, thereby limiting the hydrolysis of ACC to ethylene and thus reducing the ethylene production from ACC accumulated within the fruit. This result was consistent with the lower ethylene production in CNFC-coated fruits compared with uncoated and Semp-coated fruits (Figure 3B). Meanwhile, ACS activity peaked on day 0 of storage and then gradually decreased during the first 4–5 days of storage, but increased again during the remaining storage period in CNFC-coated and Semp-coated fruits (Figure 3D). The initial high ACS activity may be related to the subsequent appearance of skin yellowing in the obtained fruit samples. It is possible that banana fruits obtained from local markets had already reached the onset of subsequent peel yellowing before storage in our facility. The increase in ACS activity in Semp-coated and CNFC-coated fruits after 7 days of storage may be related to the delayed ripening stage of the fruit. CNFC-coated fruit had lower ACS activity than Semp-coated fruit, indicating a slower ripening process. Therefore, CNFC coating can control the physiological activity of bananas, as indicated by the reduced production of ethylene and CO2 and the decreased ACS activity, thereby delaying fruit ripening.

[0115] The effects of coating on fruit surface properties by SEM analysis are illustrated in Figures 4A–5C. The CNFC coating (Figure 4C) uniformly covered the fruit skin surface without any breaks between the epidermal cells, whereas intercellular cracks and / or breaks appeared in the uncoated fruit (Figure 4A) and the Semp-coated fruit (Figure 4B). This insufficient coverage may accelerate water loss, respiration, and fungal invasion. In addition, the size and shape of epidermal cells in the CNFC-coated fruit changed, as marked in Figure 4C. This may be due to interactions between the fibrous CNF matrix and the epidermal cells of the banana peel. Therefore, the fruit surface morphology further confirmed that the fibrous, hydrophobic CNFC coating could sufficiently bind to the banana surface, resulting in effective coating performance.

[0116] Example 10 In this example, confirmatory tests were performed on uncoated, Semp-coated, and CNFC-coated fruits. The appearance of the fruits was observed on days 3, 7, and 10 of ambient storage (Figure 5A). During the green-yellow banana period (days 0 to 3 of storage), the Semp-coated (center image in Figure 5A) and CNFC-coated (right image in Figure 5A) reduced the rate of chlorophyll degradation. During the yellow-brown banana period (days 7 to 10 of storage), the CNFC-coated fruit further reduced the occurrence of brown spots on the fruit surface compared to the uncoated and Semp-coated fruits. During the yellow stage, banana fruits continue to ripen, and the presence of polyphenol oxidase (PPO) further promotes the conversion of phenol to quinine, resulting in increased polymerization of polymers and the accumulation of brown pigments. The CNFC-coated fruit reduced enzymatic browning by delaying banana ripening and senescence during the yellow stage.

[0117] Starch testing revealed that the color of the fruit cross sections turned dark blue / black from the iodine reaction, indicating a higher starch content in CNFC-coated bananas compared with uncoated and Semp-coated fruits (Figure 5A). A similar trend was observed in the TSS on days 3 and 7 of storage, indicating that the CNFC-coated bananas resulted in the lowest TSS compared with uncoated and Semp-coated fruits (Figure 5A). These results demonstrated that the CNFC coating retards banana ripening by preventing starch hydrolysis and its conversion to soluble sugars. On the other hand, the TSS of CNFC-coated bananas was not significantly different from that of uncoated bananas on day 10 of storage, indicating that the ripening process continued properly in the bananas during storage. This result was also supported by an increase in ACS activity after day 7 of storage, indicating that the ripening process continued properly in CNFC-coated bananas.

[0118] Both the Semp-coated and CNFC-coated bananas maintained higher firmness than the uncoated samples on days 3 and 7 of storage (Figure 5B). Firmness is an important parameter for determining the ripening stage and quality of banana fruit. During ripening, pectinesterase and polygalacturonase hydrolyze pectin and starch, leading to the destruction and deterioration of cell wall structure, which then softens the fruit. Based on the results recorded and described above, a uniform surface coating of CNFC on the fruit surface could delay the physiological activity and ripening of the coated fruit through the interaction between CNFs and the epidermal cells of the banana peel, thus maintaining the firmness of the fruit during storage.

[0119] CNFC coating resulted in the lowest fruit soluble solids content compared with uncoated and Semp-coated fruits on days 3 and 7 of storage (Figure 5C). Because starch is hydrolyzed to soluble sugars during ripening, soluble solids content is a good indicator of fruit ripening. The soluble solids data demonstrated that CNFC coating further delayed fruit ripening compared with Semp coating. Meanwhile, the soluble solids content of CNFC-coated bananas was not significantly different from that of uncoated bananas on day 10 of storage, indicating that the ripening process continued properly in the stored bananas. This result was also supported by the increase in ACS activity after day 7 of storage, indicating that the ripening process continued properly in the CNFC-coated bananas.

[0120] The TA of CNFC-coated fruits was significantly (P < 0.05) higher than that of uncoated and Semp-coated fruits throughout the entire 10-day storage period (Fig. 5D). It was hypothesized that CNFC coating reduced the consumption of organic acids as primary substrates during respiration during storage due to the control of fruit physiological activity. Confirmatory testing confirmed that CNFC coating was effective in delaying ripening, retarding quality deterioration, and extending the shelf life of postharvest bananas during ambient storage.

[0121] Example 11 In this example, the effect of CNF emulsion coating on the appearance and quality parameters of various selected fruits during ambient storage was investigated. The results are shown in Figure 6. In the figure, superscripts that differ between control and coated fruit indicate significant differences (P<0.05), and WL = weight loss.

[0122] Example 12 In this example, mangoes were coated with a coating composition comprising cellulose nanofibrils and an emulsion system containing oleic acid and sucrose ester fatty acids. The mangoes were stored under ambient conditions for 12 days. It was found that application of the coating extended the green color and improved the shelf life of the fruit (see Figure 7).

[0123] Example 13 On day 12 of storage, uncoated and coated fruits were measured for weight loss, firmness, total soluble solids (TSS), and titratable acidity (TA). The only significant (P<0.05) difference was observed in TA, which was higher in fruits with coating embodiments disclosed herein than in uncoated fruits. A higher TA may indicate delayed fruit ripening. The results are shown in Table 3 below.

[0124] [Table 3]

[0125] Example 14 In this example, films produced with CH-containing CNF were evaluated for use as films for separating fruit pulp. Consistently, CH-containing CNF films (containing 20 wt.% CH (dry weight basis) at 68 kDa and 287 kDa) had significantly lower liquid absorption (lower WA values) than CH-free CNF films, indicating improved water resistance of the CH-containing CNF films. These results (see Figures 8A and 8B) suggest that the CH-containing CNF films are durable to high moisture conditions and therefore have the potential to be applied to moist surface foods as separator sheets to prevent moisture transfer between layered products. All films except the control (containing only CNF) were prepared by containing 0.5 wt.% CNF (weight ratio to water on a wet weight basis) and 10 wt.% glycerol (weight ratio to chitosan on a dry weight basis).

[0126] In view of the many possible embodiments to which the principles of the present disclosure may be applied, it should be recognized that the illustrated embodiments are merely preferred examples and should not be considered as limiting the scope of the present disclosure. Rather, the scope of the present disclosure is defined by the following claims. Applicant therefore claims as his invention all that comes within the scope and spirit of these claims.

Claims

1. 1. A coating composition comprising: cellulose nanomaterial in an amount ranging from 0.1 wt. % (wet weight basis) to 1 wt. % (wet weight basis); one or more emulsion droplets dispersed within the nanomaterial; wherein the cellulose nanomaterial comprises cellulose nanofibrils or cellulose nanocrystals, the one or more emulsion droplets comprise a fatty acid component and a sucrose fatty acid ester, the fatty acid component being present in an amount ranging from 0.1% by weight (wet weight basis) to 5% by weight (wet weight basis), the sucrose fatty acid ester being present in an amount ranging from 0.1% by weight (wet weight basis) to 2% by weight (wet weight basis), the sucrose fatty acid ester forming an outer hydrophobic region of the one or more emulsion droplets, and the fatty acid component forming an inner hydrophobic region of the one or more emulsion droplets.

2. 10. The coating composition of claim 1, wherein the cellulose nanofibrils are present in an amount ranging from 0.1 wt % (wet weight basis) to 0.5 wt % (wet weight basis).

3. 10. The coating composition of claim 1, wherein the cellulose nanocrystals are present in an amount ranging from 0.1 wt % (wet weight basis) to 1 wt % (wet weight basis).

4. 2. The coating composition of claim 1, wherein the fatty acid component is oleic acid, capric acid, lauric acid, linoleic acid, alpha-linolenic acid, palmitic acid, stearic acid, arachidic acid, and any combination thereof.

5. The coating composition of claim 1 , further comprising a functional agent, a plasticizer, or a combination thereof.

6. The coating composition of claim 5 , wherein the functional agent is chitosan.

7. The coating composition of claim 5 wherein the plasticizer is glycerol.

8. 6. The coating composition of claim 5, wherein the composition comprises a functional agent and a plasticizer, the functional agent being present in an amount ranging from 0.1 wt % (wet weight basis) to 2 wt % (wet weight basis), and the plasticizer being present in an amount ranging from 0.02 wt % (wet weight basis) to 1 wt % (wet weight basis).

9. The coating composition of claim 1 , wherein the fatty acid component is oleic acid.

10. 10. A substantially dried coating formed from the coating composition of claims 1-9, comprising greater than 0% to 10% moisture, a cellulose nanomaterial, and one or more emulsion droplets dispersed within the cellulose nanomaterial, the cellulose nanomaterial comprising cellulose nanofibrils or cellulose nanocrystals, the one or more emulsion droplets comprising a fatty acid component and a sucrose fatty acid ester, the sucrose fatty acid ester forming an outer hydrophobic layer of the one or more emulsion droplets, and the fatty acid component forming an inner hydrophobic region of the one or more emulsion droplets.

11. A plant part comprising a coating formed from the coating composition of any one of claims 1 to 9.

12. A plant part comprising the substantially dried coating of claim 10.

13. The plant part of claim 12, wherein the plant part is a tropical fruit.

14. 13. The plant part of claim 12, wherein the plant part is a banana, papaya, avocado, melon, or mango.

15. A method for coating a plant or plant part with a coating composition comprising a cellulose nanomaterial in an amount ranging from 0.1% by weight (wet weight) to 1% by weight (wet weight) and one or more types of emulsion droplets dispersed within the cellulose nanomaterial, wherein the cellulose nanomaterial comprises cellulose nanofibrils or cellulose nanocrystals, the one or more types of emulsion droplets comprise a fatty acid component and a sucrose fatty acid ester, the fatty acid component being present in an amount ranging from 0.1% by weight (wet weight) to 5% by weight (wet weight), the sucrose fatty acid ester being present in an amount ranging from 0.1% by weight (wet weight) to 2% by weight (wet weight), the sucrose fatty acid ester forming an outer hydrophobic layer of the one or more types of emulsion droplets, and the fatty acid component forming an inner hydrophobic region of the one or more types of emulsion droplets.

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