Patent Application
20200068912
This application claims the benefit of U.S. Provisional Application 62/727,501, filed Sep. 5, 2018, and incorporated herein for all purposes.
Common agricultural products are susceptible to degradation and decomposition (i.e., spoilage) when exposed to the environment. Such agricultural products can include, for example, eggs, fruits, vegetables, produce, seeds, nuts, flowers, and/or whole plants (including their processed and semi-processed forms). Edible non-agricultural products (e.g., vitamins, candy, etc.) can also be vulnerable to degradation when exposed to the ambient environment. The degradation of agricultural and other edible products can occur via abiotic means as a result of evaporative moisture loss from an external surface of the products to the atmosphere, oxidation by oxygen that diffuses into the products from the environment, mechanical damage to the surface, and/or light-induced degradation (i.e., photodegradation). Biotic stressors such as bacteria, fungi, viruses, and/or pests can also infest and decompose the products.
The cells that form the aerial surface of most plants (such as higher plants) include an outer envelope or cuticle, which provides varying degrees of protection against water loss, oxidation, mechanical damage, photodegradation, and/or biotic stressors, depending upon the plant species and the plant organ (e.g., fruit, seeds, bark, flowers, leaves, stems, etc.). Cutin, which is a biopolyester derived from cellular lipids, forms the major structural component of the cuticle and serves to provide protection to the plant against environmental stressors (both abiotic and biotic). The thickness, density, as well as the composition of the cutin (i.e., the different types of monomers that form the cutin and their relative proportions) can vary by plant species, by plant organ within the same or different plant species, and by stage of plant maturity. The cutin-containing portion of the plant can also contain additional compounds (e.g., epicuticular waxes, phenolics, antioxidants, colored compounds, proteins, polysaccharides, etc.). This variation in the cutin composition as well as the thickness and density of the cutin layer between plant species, plant organs and/or a given plant at different stages of maturation can lead to varying degrees of resistance between plant species or plant organs to attack by environmental stressors (i.e., water loss, oxidation, mechanical injury, and light) and/or biotic stressors (e.g., fungi, bacteria, viruses, insects, etc.).
Conventional approaches to preventing degradation, maintaining quality, and increasing the life of agricultural products include refrigeration and/or special packaging. Refrigeration requires capital-intensive equipment, demands constant energy expenditure, can cause damage or quality loss to the product if not carefully controlled, must be actively managed, and its benefits are lost upon interruption of a temperature-controlled supply chain. Special packaging can also require expensive equipment, consume packaging material, increase transportation costs, and require active management. Despite the benefits that can be afforded by refrigeration and special packaging, the handling and transportation of the agricultural products can cause surface abrasion or bruising that is aesthetically displeasing to the consumer and serves as points of ingress for bacteria and fungi. Moreover, the expenses associated with such approaches can add to the cost of the agricultural product.
There exists a need for new, more cost-effective approaches to prevent degradation, maintain quality, and increase the life of agricultural products. Such approaches may require less or no refrigeration, special packaging, etc.
Compositions and formulations for forming protective coatings and methods of making and using thereof are described herein. The compositions can include a first group of compounds, where each compound of the first group is selected from fatty acids, fatty acid esters, and fatty acid salts, and each compound of the first group has a carbon chain length of at least 14 carbons. The compositions can also include a second group of compounds selected from fatty acids, fatty acid esters, fatty acid salts, and combinations thereof, wherein each compound of the second group has a carbon chain length from 7 to 13 carbons. At least some of the compounds of the first group (e.g., fatty acid salts) can function as emulsifiers, allowing the composition to be dissolved, suspended, or dispersed in a solvent. At least some of the compounds of the second group can function as wetting agents or surfactants in order to improve the surface wetting of items to be coated when solutions, suspensions, or colloids that include the compositions are applied to the items. The fatty acid salts having a carbon chain length of less than 14 (e.g., from 7 to 13 carbons) can also (or alternatively) function as emulsifiers, allowing the composition to be dissolved, suspended, or dispersed in a solvent.
Accordingly, in a first aspect, a composition can include from about 50% to about 99.9% by mass of one or more first compounds selected from the group consisting of fatty acids, fatty acid esters, fatty acid salts, and combinations thereof, wherein each of the one or more first compounds has a carbon chain length of at least 14. The composition can further include from about 0.1% to about 35% by mass of one or more second compounds selected from the group consisting of fatty acids, fatty acid esters, fatty acid salts, and combinations thereof, wherein each of the one or more second compounds has a carbon chain length in a range of 7 to 13.
In a second aspect, a composition can include from about 50% to about 99.8% by mass of one or more first compounds selected from the group consisting of fatty acids, fatty acid esters, and combinations thereof, wherein each compound of the first group has a carbon chain length of at least 14. The composition can further include from about 0.1% to about 35% by mass of one or more wetting agents. The composition can further include from about 0.1% to about 25% by mass of one or more fatty acid salts, wherein each fatty acid salt has a carbon chain length of at least 14.
In a third aspect, a composition can include from about 50% to about 99.8% by mass of a first group of compounds, wherein each compound of the first group is a compound of Formula I having a carbon chain length of at least 14, and where Formula I is as defined throughout. The composition can further include from about 0.1% to about 35% by mass of a second group of compounds, wherein each compound of the second group is a compound of Formula I having a carbon chain in a range of 7 to 13. The composition can further include from about 0.1% to about 25% by mass of a third group of compounds, wherein each compound of the third group is a salt comprising a compound of Formula II. For the first and second groups of compounds, R can be selected from —H, -glyceryl, —C1-C6 alkyl, —C2-C6 alkenyl, —C2-C6 alkynyl, —C3-C7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more groups selected from halogen, hydroxyl, nitro, —CN, —NH2, —SH, —SR15, —OR14, —NR14R15, —C1-C6 alkyl, —C2-C6 alkenyl, or —C2-C6 alkynyl. For the third group of compounds, X can be a cationic moiety.
In a fourth aspect, a composition can include from about 50% to about 99% by mass of one or more fatty acid esters having carbon chain length of at least 14, and from about 1% to about 50% by mass of one or more fatty acid salts having a carbon chain length of at least 14.
In a fifth aspect, a composition can include (i) from 50% to 99% by mass of a first group of compounds, wherein each compound of the first group is a compound of Formula I, and (ii) from 1% to 50% by mass of a second group of compounds, wherein each compound of the second group is a salt of Formula II or Formula III, where Formulas I, II, and III are as defined throughout.
In a sixth aspect, a mixture (e.g., a solution, suspension, or colloid) can include a composition in a solvent, wherein the composition comprises (i) from 50% to 99% by mass of a first group of compounds, wherein each compound of the first group is a compound of Formula I, and (ii) from 1% to 50% by mass of a second group of compounds, wherein each compound of the second group is a salt of Formula II or Formula III, where Formulas I, II, and III are as defined throughout.
Any of the compositions or mixtures described herein can include one or more of the following features, either alone or in combination. The second compounds or wetting agents can have a carbon chain length of 8, 10, 11, or 12. Any of the compounds of the composition can be compounds of Formula I. The cationic moiety can be an organic or an inorganic ion. The cationic moiety can include sodium. Each of the one or more second compounds can be a wetting agent. The one or more first compounds can include monoacylglycerides and/or fatty acid salts. The fatty acid esters can include monacylglycerides. A mass ratio of the fatty acid esters (e.g., monoacylglycerides) to the fatty acid salts can be in a range of about 2 to 100 or about 2 to 99. Accordingly, a mass ratio of the first group of compounds to the second group of compounds can be in a range of 2 to 99 or 2 to 100. The composition can comprise less than 10% by mass of diglycerides. The composition can comprise less than 10% by mass of triglycerides. Each compound of the first and/or second group of compounds can have a carbon chain length of at least 14. In Formula I, R can -glyceryl. The second group of compounds can comprise SA-Na, PA-Na, MA-Na, SA-K, PA-K, or MA-K. The composition can comprise from 70% to 99% by mass of the first group of compounds and from 1% to 30% by mass of the second group of compounds. The solvent can be water, or can be at least 50% or at least 70% water by volume. A concentration of the composition in the mixture can be in a range of 0.5 to 200 mg/mL The first group of compounds can comprise one or more compounds selected from the group consisting of:
In another aspect, a mixture (e.g., a solution, suspension, or colloid) can include any of the compositions described herein in a solvent (e.g., dissolved, suspended, or dispersed in a solvent). Any of the mixtures described herein can include one or more of the following features. The solvent can be characterized as having a contact angle of at least about 70 degrees on carnauba wax. The solvent can be water or can be at least 70% water by volume. The solvent can include ethanol. The solvent can include water and ethanol. The mixture can include an antimicrobial agent, which can for example be citric acid. A concentration of the composition in the mixture can be in a range of 0.5 to 200 mg/mL. A concentration of the wetting agents in the mixture can be at least about 0.1 mg/mL.
In another aspect, a method of forming a mixture can include providing a solvent that is characterized as exhibiting a contact angle of at least about 70° (e.g., at least about 75°, at least about 80°, at least about 85°, or at least about 90°) when disposed on the surface of carnauba wax. The method can further include adding a composition to the solvent to form the mixture. The composition can include one or more fatty acids or salts or esters thereof, and/or can include compounds of Formula I, Formula II, and/or Formula III. The resulting mixture is characterized as exhibiting a contact angle less than about 85° (e.g., less than about 80°, less than about 75°, less than about 70°, or less than about 65°) when disposed on carnauba wax. The contact angle of the resulting mixture on carnauba wax can be less than the contact angle of the solvent (prior to the addition of the composition) on carnauba wax. Optionally, at least one of the fatty acids or salts or esters thereof of the composition can have a carbon chain length of 13 or less. Optionally, at least one of the fatty acids or salts or esters thereof of the composition can have a carbon chain length of 14 or greater. Optionally, the solvent can be water or can be at least 70% water by volume.
In another aspect, a method of forming a protective coating over a substrate (e.g., an agricultural product) can include applying a mixture (e.g., a solution, a suspension, or a colloid) to a surface of the substrate, the mixture comprising a composition in a solvent. The method can further include removing the solvent from the surface of the substrate, thereby causing the protective coating to be formed from the composition over the surface of the substrate. The composition can include compounds of Formula I, Formula II, and/or Formula III, where Formulas I, II, and III are as described throughout. For example, the composition can include include (i) from 50% to 99% by mass of a first group of compounds, wherein each compound of the first group is a compound of Formula I, and (ii) from 1% to 50% by mass of a second group of compounds, wherein each compound of the second group is a salt of Formula II or Formula III.
As used herein, the term “plant matter” refers to any portion of a plant, including, for example, fruits (in the botanical sense, including fruit peels and juice sacs), vegetables, leaves, stems, barks, seeds, flowers, peels, or roots. Plant matter includes pre-harvest plants or portions thereof as well as post-harvest plants or portions thereof, including, e.g., harvested fruits and vegetables, harvested roots and berries, and picked flowers.
As used herein, a “coating agent” refers to a composition including a compound or group of compounds from which a protective coating can be formed.
As used herein, the term “mass loss factor” is defined as the ratio of the average mass loss rate of uncoated produce (measured for a control group) to the average mass loss rate of the corresponding coated produce. Hence a larger mass loss factor corresponds to a greater reduction in average mass loss rate for the coated produce.
As used herein, the term “contact angle” of a liquid on a solid surface refers to an angle of the outer surface of a droplet of the liquid measured where the liquid-vapor interface meets the liquid-solid interface. For example, as shown in
As used herein, the terms “wetting agent” or “surfactant” each refer to a compound that, when added to a solvent, suspension, colloid, or solution, reduces the difference in surface energy between the solvent/suspension/colloid/solution and a solid surface on which the solvent/suspension/colloid/solution is disposed.
As used herein, the “carbon chain length” of a fatty acid or salt or ester thereof refers to the number of carbon atoms in the chain including the carbonyl carbon.
As used herein, a “long chain fatty acid”, a “long chain fatty acid ester”, or a “long chain fatty acid salt” refers to a fatty acid or ester or salt thereof, respectively, for which the carbon chain length is greater than 13 (i.e., is at least 14).
As used herein, a “medium chain fatty acid”, a “medium chain fatty acid ester”, or a “medium chain fatty acid salt” refers to a fatty acid or ester or salt thereof, respectively, for which the carbon chain length is in a range of 7 to 13 (inclusive of 7 and 13).
As used herein, a “cationic counter ion” is any organic or inorganic positively charged ion associated with a negatively charged ion. Examples of a cationic counter ion include, for example, sodium, potassium, calcium, and magnesium.
As used herein, a “cationic moiety” is any organic or inorganic positively charged ion.
The following abbreviations are used throughout. Hexadecanoic acid (i.e., palmitic acid) is abbreviated to “PA”. Octadecanoic acid (i.e., stearic acid) is abbreviated to “SA”. Tetradecanoic acid (i.e., myristic acid) is abbreviated to “MA”. (9Z)-Octadecenoic acid (i.e., oleic acid) is abbreviated to “OA”. Dodecanoic acid (e.g., lauric acid) is abbreviated to “LA”. Undecanoic acid (e.g., undecylic acid) is abbreviated to “UA”. Decanoic acid (e.g., capric acid) is abbreviated to “CA”. 1,3-dihydroxypropan-2-yl palmitate (i.e., 2-glyceryl palmitate) is abbreviated to “PA-2G”. 1,3-dihydroxypropan-2-yl octadecanoate (i.e., 2-glyceryl stearate) is abbreviated to “SA-2G”. 1,3-dihydroxypropan-2-yl tetradecanoic acid (i.e., 2-glyceryl myristate) is abbreviated to “MA-2G”. 1,3-dihydroxypropan-2-yl (9Z)-octadecenoate (i.e., 2-glyceryl oleate) is abbreviated to “OA-2G”. 2,3-dihydroxypropan-1-yl palmitate (i.e., 1-glyceryl palmitate) is abbreviated to “PA-1G”. 2,3-dihydroxypropan-1-yl octadecanoate (i.e., 1-glyceryl stearate) is abbreviated to “SA-1G”. 2,3-dihydroxypropan-1-yl tetradecanoate (i.e., 1-glyceryl myristate) is abbreviated to “MA-1G”. 2,3-dihydroxypropan-1-yl (9Z)-octadecenoate (i.e., 1-glyceryl oleate) is abbreviated to “OA-1G”. 2,3-dihydroxypropan-1-yl dodecanoate (i.e., 1-glyceryl laurate) is abbreviated to “LA-1G”. 2,3-dihydroxypropan-1-yl undecanoate (i.e., 1-glyceryl undecanoate) is abbreviated to “UA-1G”. 2,3-dihydroxypropan-1-yl decanoate (i.e., 1-glyceryl caprate) is abbreviated to “CA-1G”. Sodium salt of stearic acid is abbreviated to “SA-Na”. Sodium salt of myristic acid is abbreviated to “MA-Na”. Sodium salt of palmitic acid is abbreviated to “PA-Na”. Potassium salt of stearic acid is abbreviated to “SA-K”. Potassium salt of myristic acid is abbreviated to “MA-K”. Potassium salt of palmitic acid is abbreviated to “PA-K”. Calcium salt of stearic acid is abbreviated to “(SA)2-Ca”. Calcium salt of myristic acid is abbreviated to “(MA)2-Ca”. Calcium salt of palmitic acid is abbreviated to “(PA)2-Ca”. Magnesium salt of stearic acid is abbreviated to “(SA)2-Mg”. Magnesium salt of myristic acid is abbreviated to “(MA)2-Mg”. Magnesium salt of palmitic acid is abbreviated to “(PA)2-Mg”.
“Substituted” or “substituent”, as used herein, means an atom or group of atoms is replaced with another atom or group of atoms. Exemplary substituents include, but are not limited to, halogen, hydroxyl, nitro, cyano, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, formyl, acyl, ether, ester, keto, aryl, heteroaryl, etc.
Described herein are solutions, suspensions, or colloids containing a composition (e.g., a coating agent) in a solvent that can be used to form protective coatings over substrates such as plant matter, agricultural products, or food products. The protective coatings can, for example, prevent water loss from the substrates, oxidation of the substrates, and/or can shield the substrates from threats such as bacteria, fungi, viruses, and the like. The coatings can also protect the substrates from physical damage (e.g., bruising) and photodamage. Accordingly, the coating agents, solutions/suspensions/colloids, and the coatings formed thereof can be used to help store agricultural or other food products for extended periods of time without spoiling. In some instances, the coatings and the coating agents from which they are formed can allow for food to be kept fresh in the absence of refrigeration. The coating agents and coatings described herein can also be edible (i.e., the coating agents and coatings can be non-toxic for human consumption). In some particular implementations, the solutions/suspensions/colloids include a wetting agent or surfactant which cause the solution/suspension/colloid to better spread over the entire surface of the substrate during application, thereby improving surface coverage as well as overall performance of the resulting coating. In some particular implementations, the solutions/suspensions/colloids include an emulsifier which improves the solubility of the coating agent in the solvent and/or allows the coating agent to be suspended or dispersed in the solvent. The wetting agent and/or emulsifier can each be a component of the coating agent, or can be separately added to the solution/suspension/colloid.
Plant matter (e.g., agricultural products) and other degradable items can be protected against degradation from biotic or abiotic stressors by forming a protective coating over the outer surface of the product. The coating can be formed by adding the constituents of the coating (herein collectively a “coating agent”) to a solvent (e.g., water and/or ethanol) to form a mixture (e.g., a solution, suspension, or colloid), applying the mixture to the outer surface of the product to be coated, e.g., by dipping the product in the mixture or by spraying the mixture over the surface of the product, and then removing the solvent from the surface of the product, e.g., by allowing the solvent to evaporate, thereby causing the coating to be formed from the coating agent over the surface of the product. The coating agent can be formulated such that the resulting coating provides a barrier to water and/or oxygen transfer, thereby preventing water loss from and/or oxidation of the coated product. The coating agent can additionally or alternatively be formulated such that the resulting coating provides a barrier to CO2, ethylene and/or other gas transfer.
Coating agents including long chain fatty acids (e.g., palmitic acid, stearic acid, myristic acid, and/or other fatty acids having a carbon chain length greater than 13) and/or esters or salts thereof can both be safe for human consumption and can be used as coating agents to form coatings that are effective at reducing mass loss and oxidation in a variety of produce. For example, coatings formed from coating agents that include various combinations of palmitic acid, myristic acid, stearic acid, 1-glyceryl esters of palmitic acid (i.e., 2,3-dihydroxypropan-1-yl palmitate, herein “PA-1G”), 2-glyceryl esters of palmitic acid (i.e., 1,3-dihydroxypropan-2-yl palmitate, herein “PA-2G”), 1-glyceryl esters of myristic acid (i.e., 2,3-dihydroxypropan-1-yl tetradecanoate, herein “MA-1G”), 1-glyceryl esters of stearic acid (i.e., 2,3-dihydroxypropan-1-yl octadecenoate, herein “SA-1G”), and/or other long chain fatty acids or salts or esters thereof have been shown to be effective at reducing mass loss rates in many types of produce, for example finger limes, avocados, blueberries, and lemons. Specific examples of a variety of coatings and their effects in reducing mass loss rates in various types of produce are provided in Examples 1-4 below.
Medium chain fatty acids (e.g., having a carbon chain length in a range of 7 to 13) and/or salts or esters thereof can also be used as coating agents to form coatings over produce or other plant matter or agricultural products using the methods described above. However, these compounds have typically been found to cause damage to the produce or plant matter, and also typically result in minimal to no reduction in mass loss rates. For example, treating avocados with a solution of 1-glyceryl esters of undecanoic acid (i.e., 2,3-dihydroxypropan-1-yl undecanoate, herein “UA-1G”) suspended in water at a concentration as low as 5 mg/mL (UA-1G has a carbon chain length of 11) was shown to cause the avocados' skins to change from being virtually entirely green to having a high density of black discolored regions as a result of skin damage caused by the UA-1G. As seen in
It is generally expected that for coatings that are formulated to prevent water loss from or oxidation of coated substrates such as produce, thicker coatings will be less permeable to water and oxygen as compared to thinner coatings formed from the same coating agent, and should therefore result in lower mass loss rates as compared to thinner coatings. Thicker coatings can be formed by increasing the concentration of the coating agent in the solution/suspension/colloid and applying a similar volume of solution/suspension/colloid to each piece of (similarly sized) produce. The effect of increasing the coating thickness on harvested produce is demonstrated in
For certain solutions/suspensions/colloids including long chain fatty acids and/or salts or esters thereof dissolved or suspended or dispersed in a solvent, protective coatings formed over certain types of produce by the methods described above were found to reduce the mass loss rate of the produce but did not result in lower mass loss rates as the thickness of the coating was increased, as in the blueberries described above. Instead, the mass loss rate in these cases was found to be lower than in uncoated produce but was approximately the same for thinner and thicker coatings. For example,
Surprisingly, for many cases in which the mass loss rate did not vary with coating thickness (as with the lemons in
The beneficial effects of adding small concentrations of medium chain fatty acids or salts or esters thereof to coating solutions/suspensions/colloids that include long chain fatty acids or salts/esters thereof are shown in
While treating the lemons with the coating agents that only included long chain fatty acid salts and esters (804 and 806) did reduce the average mass loss rate of the lemons, the mass loss factor did not substantially increase when the concentration of the coating agent compounds in the mixture was increased from 10 mg/mL (804) to 30 mg/mL (806). However, the mass loss factor did increase substantially when a small concentration of medium chain fatty acid esters (5 mg/mL of UA-1G) was added to each of the mixtures. Specifically, adding 5 mg/mL of medium chain esters to the mixture with 10 mg/mL of long chain fatty acid esters/salts caused the mass loss factor of the lemons due to the resulting coatings to increase from about 1.5 (bar 804) to about 1.9 (bar 808), corresponding to an increase in mass loss factor of over 25%. Adding 5 mg/mL of medium chain esters to the mixture with 30 mg/mL of long chain fatty acid esters/salts caused the mass loss factor of the lemons due to the resulting coatings to increase from about 1.7 (bar 806) to about 2.6 (bar 810), corresponding to an increase in mass loss factor of over 50%. The mass loss factor of the lemons corresponding to bar 810 was in fact substantially larger than that of groups of lemons coated with any of the concentrations of long chain fatty acid esters/salts in solution for which medium chain fatty acids or salts/esters thereof were not also added.
Without wishing to be bound by theory, it is believed that many of the mixtures (i.e., solutions, suspensions, or colloids) that lacked the medium chain fatty acids or salts/esters thereof were not sufficiently wetting the entire surface of the produce to which they were applied due to a difference in surface energy of the mixture as compared to that of the surface of the produce. Consequently, the coatings formed from these mixtures did not completely cover the surface of the produce. As such, mass loss was dominated by water loss through the openings in the coating, and was relatively unaffected by increasing the coating thickness. Thus, in cases where this effect was believed to occur (e.g., in lemons coated from a water-based solution such as in
It is further believed that the medium chain fatty acids that were added to the mixtures acted as surfactants/wetting agents, reducing the contact angle of the mixture on the surface of the produce. The addition of the wetting agents was believed to improve coverage of the mixture over the surface of the produce, thereby allowing a substantially contiguous coating to be formed over the entire surface. Consequently, the mass loss rates of coated produce were found to decrease with increasing coating thickness, and overall mass loss rates were found to be substantially reduced as compared to produce coated with similar mixtures that lacked the wetting agents. Furthermore, the long chain fatty acids and/or salts or esters thereof appeared to suppress surface damage to the produce observed in cases where the wetting agent was dissolved, dispersed, or suspended in the mixture and applied on its own without also including the long chain fatty acids and/or salts or esters thereof. Additional evidence of these effects is provided below.
Through extensive experimentation, it was found that the contact angle of droplets of some solvents and coating solutions/suspensions on the surfaces of at least some types of produce was quite large, indicating a large difference in surface energy of the droplets as compared to the surface of the produce. This effect was particularly evident in cases where the coating solution/suspension was at least 70% water by volume, since the surfaces of many plants or other agricultural products often tend to be hydrophobic due to the presence of epicuticular waxes. This phenomenon was characterized as follows. Droplets of solvent or coating solution/suspension/colloid (i.e., solvent with coating agent dissolved, suspended or dispersed therein) were deposited either directly on produce surfaces or directly on carnauba, candellila, or paraffin wax (carnauba, candellila, and paraffin wax all tend to have similar native hydrophobicity to that of the surfaces of lemons as well as many other types of produce, see
Increasing the concentration of the wetting agent (e.g., the medium chain fatty acids and/or salts or esters thereof) in water-based or high water content coating mixtures generally decreased the contact angle of the solution/suspension/colloid on the produce or wax surface. For example, as shown in
It was further found that for many mixtures, the addition of medium chain fatty acids and/or salts or esters thereof having a smaller chain length caused a larger reduction in contact angle of droplets on produce than addition of similar concentrations of medium chain fatty acids and/or salts or esters thereof having a longer chain length. For example,
As seen in
As previously described, carnauba, candellila, and paraffin wax were all found to have similar native hydrophobicity to that of the surfaces of lemons (as well as other produce). Hence the wetting properties (e.g., contact angle) of mixtures characterized on carnauba, candellila, or paraffin wax surfaces are typically predictive of the wetting properties of the mixtures on produce. For example,
The effects of adding small concentrations of LA-1G and CA-1G to coating mixtures used to form coatings on avocados is shown in the graph of
The addition of the CA-1G (carbon chain length of 10) to the coating mixture increased the mass loss factor to about 2.35 for a CA-1G concentration of 1 mg/mL (bar 1303), to about 2.24 for a CA-1G concentration of 2.5 mg/mL (bar 1304), and to about 2.18 for a CA-1G concentration of 4 mg/mL (bar 1305). So while the mass loss factor was substantially larger for all concentrations of CA-1G in a range of 1 to 4 mg/mL as compared to mixtures lacking the medium chain fatty acid esters (bar 1302), the mass loss factor appeared to decrease slightly as the concentration of CA-1G was increased. Without wishing to be bound by theory, it is believed that the addition of CA-1G at all concentrations of at least 1 mg/mL was effective at improving the wetting of the solution on the surfaces of the avocados, but that increasing the concentration of the CA-1G began to cause some moderate damage to the avocados, thereby mitigating the beneficial surface wetting effects and causing a slight decrease in the mass loss factor.
Still referring to
The effects of adding small concentrations of CA-1G to coating mixtures used to form coatings on cherries is shown in
The effects of adding small concentrations of UA-1G to coating mixtures used to form coatings on finger limes is shown
As described throughout, wetting agents can be included in coating solutions/suspensions/colloids in order to improve the surface wetting of substrates to which the solutions/suspensions/colloids are applied, thereby resulting in improved surface coverage of the coatings that are formed thereover. The wetting agents can be included within or as part of the coating agent that is dissolved or suspended in the solvent to form the coating solution/suspension/colloid. That is, a sub-group of the compounds of the coating agent can cause a change in surface energy of the solvent to which the coating agent is added, thereby acting as a wetting agent. Alternatively, the wetting agent can be a separate compound (or group of compounds) from the coating agent, and can be added to the solvent either before, after, or at the same time as the coating agent.
Alternatively, the wetting agent can be a separate compound (or group of compounds) from the coating agent and can be applied to the surface prior to applying the coating agent. For example, the wetting agent can first be added to a separate solvent to form a wetting agent solution/suspension/colloid. The wetting agent solution/suspension/colloid can then be applied to the surface, after which the coating solution/suspension/colloid is applied to the surface to form the coating. Priming of the surface in this manner can improve the surface wetting of the coating solution/suspension/colloid with the surface.
An example of the surface priming effect described above is shown in
The solvent to which the coating agent and wetting agent (when separate from the coating agent) is added to form the solution/suspension/colloid can, for example, be water, methanol, ethanol, isopropanol, butanol, acetone, ethyl acetate, chloroform, acetonitrile, tetrahydrofuran, diethyl ether, methyl tert-butyl ether, an alcohol, any other suitable solvent, or a combination thereof. The resulting solutions, suspensions, or colloids can be suitable for forming coatings on agricultural products. For example, the solutions, suspensions, or colloids can be applied to the surface of the agricultural product, after which the solvent can be removed (e.g., by evaporation or convective drying), leaving a protective coating formed from the coating agent on the surface of the agricultural product.
While a number of the solvents above (particularly water and ethanol) can be safely and effectively used in solutions/suspensions/colloids that are applied to edible products such as produce or other agricultural products, in many cases it can be advantageous to use either water or otherwise a solvent which is at least about 40% (and in many cases higher) water by volume. This is because water is typically cheaper than other suitable solvents and can also be safer to work with than solvents that have a higher volatility and/or a lower flash point (e.g., acetone or alcohols such as isopropanol or ethanol). Accordingly, for any of the solutions/suspensions/colloids described herein, the solvent or solution/suspension/colloid can be at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% water by mass or by volume. In some implementations, the solvent includes a combination of water and ethanol, and can optionally be at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% water by volume. In some implementations, the solvent or solution/suspension/colloid can be about 40% to 100% water by mass or volume, about 40% to 99% water by mass or volume, about 40% to 95% water by mass or volume, about 40% to 90% water by mass or volume, about 40% to 85% water by mass or volume, about 40% to 80% water by mass or volume, about 50% to 100% water by mass or volume, about 50% to 99% water by mass or volume, about 50% to 95% water by mass or volume, about 50% to 90% water by mass or volume, about 50% to 85% water by mass or volume, about 50% to 80% water by mass or volume, about 60% to 100% water by mass or volume, about 60% to 99% water by mass or volume, about 60% to 95% water by mass or volume, about 60% to 90% water by mass or volume, about 60% to 85% water by mass or volume, about 60% to 80% water by mass or volume, about 70% to 100% water by mass or volume, about 70% to 99% water by mass or volume, about 70% to 95% water by mass or volume, about 70% to 90% water by mass or volume, about 70% to 85% water by mass or volume, about 80% to 100% water by mass or volume, about 80% to 99% water by mass or volume, about 80% to 97% water by mass or volume, about 80% to 95% water by mass or volume, about 80% to 93% water by mass or volume, about 80% to 90% water by mass or volume, about 85% to 100% water by mass or volume, about 85% to 99% water by mass or volume, about 85% to 97% water by mass or volume, about 85% to 95% water by mass or volume, about 90% to 100% water by mass or volume, about 90% to 99% water by mass or volume, about 90% to 98% water by mass or volume, or about 90% to 97% water by mass or volume.
In view of the above, for some applications the solvent can be a low wetting solvent (i.e., a solvent exhibiting a large contact angle with respect to the surface to which it is applied). For example, in the absence of any added wetting agents or other surfactants, the contact angle between the solvent and either (a) carnauba wax, (b) candelilla wax, (c) paraffin wax, or (d) the surface of a non-waxed lemon can be at least about 70°, for example at least about 75°, 80°, 85°, or 90°. Addition of any of the wetting agents described herein to the solvent, either alone or in combination with other compounds or coating agents, can cause the contact angle between the resulting solution/suspension/colloid and either (a) carnauba wax, (b) candelilla wax, (c) paraffin wax, or (d) the surface of a non-waxed lemon to be less than about 85°, for example less than about 80°, 75°, 70°, 65°, 60°, 55°, 50°, 45°, 40°, 35°, 30°, 25°, 20°, 15°, 10°, 5°, or 0°.
The coating agent that is added to or dissolved, suspended, or dispersed in the solvent to form the coating solution/suspension/colloid can be any compound or combination of compounds capable of forming a protective coating over the substrate to which the solution/suspension/colloid is applied. The coating agent can be formulated such that the resulting coating protects the substrate from biotic and/or abiotic stressors. For example, the coating can prevent or suppress the transfer of oxygen and/or water, thereby preventing the substrate from oxidizing and/or from losing water via transpiration/osmosis/evaporation. In cases where the substrate is perishable and/or edible, for example when the substrate is a plant, an agricultural product, or a piece of produce, the coating agent is preferably composed of non-toxic compounds that are safe for consumption. For example, the coating agent can be formed from or include fatty acids and/or salts or esters thereof. The fatty acid esters can, for example, be ethyl esters, methyl esters, or glyceryl esters (e.g., 1-glyceryl or 2-glyceryl esters).
Coating agents formed from or containing a high percentage of long chain fatty acids and/or salts or esters thereof (e.g., having a carbon chain length of at least 14) have been found to be effective at forming protective coatings over a variety of substrates that can prevent water loss from and/or oxidation of the substrate. The addition of one or more medium chain fatty acids and/or salts or esters thereof (or other wetting agents) can further improve the performance of the coatings. Accordingly, the coating agents herein can include one or more compounds of Formula I, wherein Formula I is:
wherein:
R is selected from —H, -glyceryl, —C1-C6 alkyl, —C2-C6 alkenyl, —C2-C6 alkynyl, —C3-C7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more groups selected from halogen (e.g., C1, Br, or I), hydroxyl, nitro, —CN, —NH2, —SH, —SR15, —OR14, —NR14R15, C1-C6 alkyl, C2-C6 alkenyl, or C2-C6 alkynyl;
R1, R2, R5, R6, R9, R10, R11, R12 and R13 are each independently, at each occurrence, —H, —(C═O)R14, —(C═O)H, —(C═O)OH, —(C═O)OR14, —(C═O)—O—(C═O)R14, —O(C═O)R14, —OR14, —NR14R15, —SR14, halogen, —C1-C6 alkyl, —C2-C6 alkenyl, —C2-C6 alkynyl, —C3-C7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more —OR14, —NR14R15, —SR14, or halogen;
R3, R4, R7, and R8 are each independently, at each occurrence, —H, —OR14, —NR14R15, —SR14, halogen, —C1-C6 alkyl, —C2-C6 alkenyl, —C2-C6 alkynyl, —C3-C7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more —OR14, —NR14R15, —SR14, or halogen; or
R3 and R4 can combine with the carbon atoms to which they are attached to form a C3-C6 cycloalkyl, a C4-C6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or
R7 and R8 can combine with the carbon atoms to which they are attached to form a C3-C6 cycloalkyl, a C4-C6 cycloalkenyl, or 3- to 6-membered ring heterocycle;
R14 and R15 are each independently, at each occurrence, —H, aryl, heteroaryl, —C1-C6 alkyl, —C2-C6 alkenyl, or —C2-C6 alkynyl;
the symbol represents a single bond or a cis or trans double bond;
n is 0, 1, 2, 3, 4, 5, 6, 7 or 8;
m is 0, 1, 2 or 3;
q is 0, 1, 2, 3, 4 or 5; and
r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
In some embodiments, R is selected from —H, —CH3, or —CH2CH3. In some embodiments, R is selected from —H, -glyceryl, —C1-C6 alkyl, —C2-C6 alkenyl, —C2-C6 alkynyl, —C3-C7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more C1-C6 alkyl or hydroxyl.
As further described herein, the coating agents can additionally or alternatively include fatty acid salts such as sodium salts (e.g., SA-Na, PA-Na, or MA-Na), potassium salts (e.g., SA-K, PA-K, MA-K), calcium salts (e.g., (SA)2-Ca, (PA)2-Ca, or (MA)2-Ca) or magnesium salts (e.g., (SA)2-Mg, (PA)2-Mg, or (MA)2-Mg). Accordingly, the coating agents herein can include one or more compounds of Formula II or Formula III, wherein Formula II and Formula III are:
wherein for each formula:
X is a cationic moiety;
Xp+ is a cationic counter ion having a charge state p, and p is 1, 2, or 3;
R1, R2, R5, R6, R9, R10, R11, R12 and R13 are each independently, at each occurrence, —H, —(C═O)R14, —(C═O)H, —(C═O)OH, —(C═O)OR14, —(C═O)—O—(C═O)R14, —O(C═O)R14, —OR14, —NR14R15, —SR14, halogen, —C1-C6 alkyl, —C2-C6 alkenyl, —C2-C6 alkynyl, —C3-C7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more —OR14, —NR14R15, —SR14, or halogen;
R3, R4, R7, and R8 are each independently, at each occurrence, —H, —OR14, —NR14R15, —SR14, halogen, —C1-C6 alkyl, —C2-C6 alkenyl, —C2-C6 alkynyl, —C3-C7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more —OR14, —NR14R15, —SR14, or halogen; or
R3 and R4 can combine with the carbon atoms to which they are attached to form a C3-C6 cycloalkyl, a C4-C6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or
R7 and R8 can combine with the carbon atoms to which they are attached to form a C3-C6 cycloalkyl, a C4-C6 cycloalkenyl, or 3- to 6-membered ring heterocycle;
R14 and R15 are each independently, at each occurrence, —H, aryl, heteroaryl, —C1-C6 alkyl, —C2-C6 alkenyl, or —C2-C6 alkynyl;
the symbol represents a single bond or a cis or trans double bond;
n is 0, 1, 2, 3, 4, 5, 6, 7 or 8;
m is 0, 1, 2 or 3;
q is 0, 1, 2, 3, 4 or 5; and
r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
Any of the coating agents described herein can include one or more of the following medium chain fatty acid compounds (e.g., compounds of Formula I):
Any of the coating agents described herein can include one or more of the following long chain fatty acid compounds (e.g., compounds of Formula I):
The coating agents herein can include one or more of the following medium chain fatty acid methyl ester compounds (e.g., compounds of Formula I):
The coating agents herein can include one or more of the following long chain fatty acid methyl ester compounds (e.g., compounds of Formula I):
The coating agents herein can include one or more of the following medium chain fatty acid ethyl ester compounds (e.g., compounds of Formula I):
The coating agents herein can include one or more of the following long chain fatty acid ethyl ester compounds (e.g., compounds of Formula I):
The coating agents herein can include one or more of the following medium chain fatty acid 2-glyceryl ester compounds (e.g., compounds of Formula I):
The coating agents herein can include one or more of the following long chain fatty acid 2-glyceryl ester compounds (e.g., compounds of Formula I):
The coating agents herein can include one or more of the following medium chain fatty acid 1-glyceryl ester compounds (e.g., compounds of Formula I):
The coating agents herein can include one or more of the following long chain fatty acid 1-glyceryl ester compounds (e.g., compounds of Formula I):
The coating agents herein can include one or more of the following fatty acid salts (e.g., compounds of Formula II or Formula III), where X is a cationic counter ion and n represents the charge state (i.e., the number of proton-equivalent charges) of the cationic counter ion:
In some embodiments, n is 1, 2, or 3. In some embodiments, X is sodium, potassium, calcium, or magnesium.
As previously described, coating agents formed predominantly of various combinations of compounds of Formula I (e.g., coating agents that are at least 50% compounds of Formula I by mass or by molar composition) each having a carbon chain length of at least 14 have been shown to form protective coatings on produce and other agricultural products that are effective at reducing moisture loss and oxidation. As also previously described, the coatings can be formed over the outer surface of the agricultural product by dissolving, suspending, or dispersing the coating agent in a solvent to form a mixture, applying the mixture to the surface of the agricultural product (e.g., by spray coating the product, by dipping the product in the mixture, or by brushing the mixture onto the surface of the product), and then removing the solvent (e.g., by allowing the solvent to evaporate). The solvent can include any polar, non-polar, protic, or aprotic solvents, including any combinations thereof. Examples of solvents that can be used include water, methanol, ethanol, isopropanol, butanol, acetone, ethyl acetate, chloroform, acetonitrile, tetrahydrofuran, diethyl ether, methyl tert-butyl ether, any other suitable solvent or combinations thereof. In cases where the coating is going to be applied to plants or other edible products, it may be preferable to use a solvent that is safe for consumption, for example water, ethanol, or combinations thereof. Depending on the solvent that is used, the solubility limit of the coating agent in the solvent may be lower than desired for particular applications. For example, when compounds of Formula I are used as the coating agent and the solvent is water (or is predominantly water), the solubility limit of the coating agent may be relatively low. In these cases it may still be possible to add the desired concentration of coating agent to the solvent and form a suspension or colloid.
In order to improve the solubility of the coating agent in the solvent, or to allow the coating agent to be suspended or dispersed in the solvent, the coating agent can further include an emulsifier. When the coatings are to be formed over plants or other edible products, it may be preferable that the emulsifier be safe for consumption. Furthermore, it is also preferable that the emulsifier either not be incorporated into the coating or, if the emulsifier is incorporated into the coating, that it does not degrade the performance of the coating.
Through extensive experimentation, it has been shown that organic salts (e.g., compounds of Formula II or Formula III) added to the coating agent can increase the solubility of the coating agent or allow the coating agent to be suspended or dispersed in solvents having a substantial water content (e.g., solvents that are at least 50% water by volume), provided that the concentration of the salts is not too low (relative to the concentration of compounds of Formula I). Furthermore, the added salts do not substantially degrade the performance of subsequently formed coatings provided that the concentration of the salts (relative to the concentration of the compounds of Formula I) is not too high.
For example, coating agents including a first group of compounds of Formula I mixed with a second group of compounds of Formula II and/or III can be added to water to form a suspension by heating the water to about 70° C., adding the coating agent, and then cooling the resulting mixture to about room temperature (or a lower temperature). The cooled mixture can then be applied to substrates such as produce to form a protective coating, as described throughout. However, it has been found that when the compounds of Formula I make up at least 50% of the mass of the coating agent and the compounds of Formula II and/or III make up less than about 3% of the coating agent, the coating agent either cannot be suspended in the water at the elevated temperature, or the coating agent can be suspended in the water at the higher temperature but then crashes out as the temperature is reduced, thus preventing coatings from being able to be formed from the mixture.
Additionally, if the concentration of compounds of Formula II and/or III is too high, the performance of the resulting coatings can be degraded. For example, as shown in
In view of the above, compositions (e.g., coating agents) can include a first group of compounds that includes one or more compounds of Formula I (e.g., fatty acids or esters thereof) and a second group of compounds that includes one or more salts of Formula II or Formula III (e.g., fatty acid salts). The compound(s) of Formula I and/or the salt(s) of Formula II or III can optionally have a carbon chain length of at least 14. A mass ratio of the first group of compounds (e.g., compounds of Formula I such as fatty acids or esters, including monoacylglycerides) to the second group of compounds (salts of Formula II or III, e.g., fatty acid salts) can, for example, be in a range of about 2 to 200, for example about 2 to 100, 2 to 99, 2 to 90, 2 to 80, 2 to 70, 2 to 60, 2 to 50, 2 to 40, 2 to 30, 2 to 25, 2 to 20, 2 to 15, 2 to 10, 2.5 to 200, 2.5 to 100, 2.5 to 90, 2.5 to 80, 2.5 to 70, 2.5 to 60, 2.5 to 50, 2.5 to 40, 2.5 to 30, 2.5 to 25, 2.5 to 20, 2.5 to 15, 2.5 to 10, 3 to 200, 3 to 100, 3 to 90, 3 to 80, 3 to 70, 3 to 60, 3 to 50, 3 to 40, 3 to 30, 3 to 25, 3 to 20, 3 to 15, 3 to 10, 4 to 200, 4 to 100, 4 to 90, 4 to 80, 4 to 70, 4 to 60, 4 to 50, 4 to 40, 4 to 30, 4 to 25, 4 to 20, 4 to 15, 4 to 10, 5 to 200, 5 to 100, 5 to 90, 5 to 80, 5 to 70, 5 to 60, 5 to 50, 5 to 40, 5 to 30, 5 to 25, 5 to 20, 5 to 15, 5 to 10, 10 to 100, 10 to 99, 10 to 90, 10 to 80, 10 to 70, 10 to 60, 10 to 50, 10 to 40, 10 to 30, 10 to 25, 10 to 20, 10 to 15, 15 to 100, 15 to 99, 15 to 90, 15 to 80, 15 to 70, 15 to 60, 15 to 50, 15 to 40, 15 to 30, 15 to 25, or 15 to 20.
As described above, the coating agent can be added to or dissolved, suspended, or dispersed in a solvent to form a colloid, suspension, or solution. The various components of the coating agent (e.g., the compounds of Formula I and the salts) can be combined prior to being added to the solvent and then added to the solvent together. Alternatively, the components of the coating agent can be kept separate from one another and then be added to the solvent consecutively (or at separate times).
The concentration of the first group of compounds (compounds of Formula I) in the solvent/solution/suspension/colloid can, for example, be in a range of about 1 mg/mL to about 200 mg/mL, such as about 1 to 150 mg/mL, 1 to 100 mg/mL, 1 to 90 mg/mL, 1 to 80 mg/mL, 1 to 75 mg/mL, 1 to 70 mg/mL, 1 to 65 mg/mL, 1 to 60 mg/mL, 1 to 55 mg/mL, 1 to 50 mg/mL, 1 to 45 mg/mL, 1 to 40 mg/mL, 2 to 200 mg/mL, 2 to 150 mg/mL, 2 to 100 mg/mL, 2 to 90 mg/mL, 2 to 80 mg/mL, 2 to 75 mg/mL, 2 to 70 mg/mL, 2 to 65 mg/mL, 2 to 60 mg/mL, 2 to 55 mg/mL, 2 to 50 mg/mL, 2 to 45 mg/mL, 2 to 40 mg/mL, 5 to 200 mg/mL, 5 to 150 mg/mL, 5 to 100 mg/mL, 5 to 90 mg/mL, 5 to 80 mg/mL, 5 to 75 mg/mL, 5 to 70 mg/mL, 5 to 65 mg/mL, 5 to 60 mg/mL, 5 to 55 mg/mL, 5 to 50 mg/mL, 5 to 45 mg/mL, 5 to 40 mg/mL, 10 to 200 mg/mL, 10 to 150 mg/mL, 10 to 100 mg/mL, 10 to 90 mg/mL, 10 to 80 mg/mL, 10 to 75 mg/mL, 10 to 70 mg/mL, 10 to 65 mg/mL, 10 to 60 mg/mL, 10 to 55 mg/mL, 10 to 50 mg/mL, 10 to 45 mg/mL, or 10 to 40 mg/mL.
The concentration of the second group of compounds (salts of Formula II or Formula III, e.g., fatty acid salts) in the solvent/solution/suspension/colloid can, for example, be in a range of about 0.01 mg/mL to about 80 mg/mL, such as about 0.01 to 75 mg/mL, 0.01 to 70 mg/mL, 0.01 to 65 mg/mL, 0.01 to 60 mg/mL, 0.01 to 55 mg/mL, 0.01 to 50 mg/mL, 0.01 to 45 mg/mL, 0.01 to 40 mg/mL, 0.01 to 35 mg/mL, 0.01 to 30 mg/mL, 0.01 to 25 mg/mL, 0.01 to 20 mg/mL, 0.01 to 15 mg/mL, 0.01 to 10 mg/mL, 0.1 to 80 mg/mL, 0.1 to 75 mg/mL, 0.1 to 70 mg/mL, 0.1 to 65 mg/mL, 0.1 to 60 mg/mL, 0.1 to 55 mg/mL, 0.1 to 50 mg/mL, 0.1 to 45 mg/mL, 0.1 to 40 mg/mL, 0.1 to 35 mg/mL, 0.1 to 30 mg/mL, 0.1 to 25 mg/mL, 0.1 to 20 mg/mL, 0.1 to 15 mg/mL, 0.1 to 10 mg/mL, 1 to 80 mg/mL, 1 to 75 mg/mL, 1 to 70 mg/mL, 1 to 65 mg/mL, 1 to 60 mg/mL, 1 to 55 mg/mL, 1 to 50 mg/mL, 1 to 45 mg/mL, 1 to 40 mg/mL, 1 to 35 mg/mL, 1 to 30 mg/mL, 1 to 25 mg/mL, 1 to 20 mg/mL, 1 to 15 mg/mL, 1 to 10 mg/mL, 2 to 80 mg/mL, 2 to 75 mg/mL, 2 to 70 mg/mL, 2 to 65 mg/mL, 2 to 60 mg/mL, 2 to 55 mg/mL, 2 to 50 mg/mL, 2 to 45 mg/mL, 2 to 40 mg/mL, 2 to 35 mg/mL, 2 to 30 mg/mL, 2 to 25 mg/mL, 2 to 20 mg/mL, 2 to 15 mg/mL, or 2 to 10 mg/mL.
The concentration of the composition (e.g., the coating agent) in the solvent/solution/suspension/colloid can, for example, be in a range of about 1 mg/mL to about 200 mg/mL, such as about 1 to 150 mg/mL, 1 to 100 mg/mL, 1 to 90 mg/mL, 1 to 80 mg/mL, 1 to 75 mg/mL, 1 to 70 mg/mL, 1 to 65 mg/mL, 1 to 60 mg/mL, 1 to 55 mg/mL, 1 to 50 mg/mL, 1 to 45 mg/mL, 1 to 40 mg/mL, 2 to 200 mg/mL, 2 to 150 mg/mL, 2 to 100 mg/mL, 2 to 90 mg/mL, 2 to 80 mg/mL, 2 to 75 mg/mL, 2 to 70 mg/mL, 2 to 65 mg/mL, 2 to 60 mg/mL, 2 to 55 mg/mL, 2 to 50 mg/mL, 2 to 45 mg/mL, 2 to 40 mg/mL, 5 to 200 mg/mL, 5 to 150 mg/mL, 5 to 100 mg/mL, 5 to 90 mg/mL, 5 to 80 mg/mL, 5 to 75 mg/mL, 5 to 70 mg/mL, 5 to 65 mg/mL, 5 to 60 mg/mL, 5 to 55 mg/mL, 5 to 50 mg/mL, 5 to 45 mg/mL, 5 to 40 mg/mL, 10 to 200 mg/mL, 10 to 150 mg/mL, 10 to 100 mg/mL, 10 to 90 mg/mL, 10 to 80 mg/mL, 10 to 75 mg/mL, 10 to 70 mg/mL, 10 to 65 mg/mL, 10 to 60 mg/mL, 10 to 55 mg/mL, 10 to 50 mg/mL, 10 to 45 mg/mL, or 10 to 40 mg/mL.
As also described above and demonstrated in the examples below, the coating solutions/suspensions/colloids can further include a wetting agent that serves to reduce the contact angle between the solution/suspension/colloid and the surface of the substrate being coated. The wetting agent can be included as a component of the coating agent and therefore added to the solvent at the same time as other components of the coating agent. Alternatively, the wetting agent can be separate from the coating agent and can be added to the solvent either before, after, or at the same time as the coating agent. Alternatively, the wetting agent can be separate from the coating agent, and can be applied to a surface before the coating agent in order to prime the surface.
The wetting agent can be a fatty acid or salt or ester thereof. The wetting agent can be a compound or group of compounds of Formula I, II, or III, where Formulas I, II, and III are given above. In particular, the wetting agent compounds can each have a carbon chain length of 13 or less. For example, the carbon chain length can be, 7, 8, 9, 10, 11, 12, 13, in a range of 7 to 13, or in a range of 8 to 12. The wetting agent can also or alternatively be one or more of a phospholipid, a lysophospholipid, a glycoglycerolipid, a glycolipid, an ascorbyl ester of a fatty acid, an ester of lactic acid, an ester of tartaric acid, an ester of malic acid, an ester of fumaric acid, an ester of succinic acid, an ester of citric acid, or an ester of pantothenic acid. In some embodiments, the wetting agents included in the mixtures herein are edible and/or safe for consumption.
Prior to adding the wetting agent to the solvent (and either before or after adding the coating agent for cases where the wetting agent and coating agent are separate), the contact angle between the solvent/solution/suspension/colloid and carnauba, candelilla, or paraffin wax can be at least about 70°, for example at least about 75°, at least about 80°, at least about 85°, or at least about 90°. After adding the wetting agent to the solvent (and either before or after adding the coating agent for cases where the wetting agent and coating agent are separate), the contact angle between the resulting solution/suspension/colloid and carnauba, candelilla, or paraffin wax can be less than 85°, for example less than about 80°, less than about 75°, less than about 70°, less than about 65°, less than about 60°, less than about 55°, less than about 50°, less than about 45°, less than about 40°, less than about 35°, less than about 30°, less than about 25°, less than about 20°, less than about 15°, less than about 10°, less than about 5°, or about 0°.
Because the wetting agents can in many cases damage the substrate being coated, the concentration of the wetting agent compounds can be less than that of the other components of the coating agent. However, if the concentration of the wetting agents added to the solvent is too low, the surface energy of the resulting solution/suspension/colloid may not be substantially different from that of the solvent, in which case improved surface wetting of the substrate may not be achieved.
In some embodiments, compounds used as wetting agents can also (or alternatively) be used as emulsifiers. For example, in some embodiments, a medium chain fatty acid (e.g., having a carbon chain length of 7, 8, 9, 10, 11, 12, or 13) or salt or ester thereof is used as an emulsifier (and optionally also functions as a wetting agent) in the composition, thereby enabling the composition to be dissolved or suspended in the solvent. In some embodiments, a phospholipid, a lysophospholipid, a glycoglycerolipid, a glycolipid, an ascorbyl ester of a fatty acid, an ester of lactic acid, an ester of tartaric acid, an ester of malic acid, an ester of fumaric acid, an ester of succinic acid, an ester of citric acid, or an ester of pantothenic acid is included in the composition and functions as an emulsifier (and optionally also functions as a wetting agent).
In view of the above, any of the compositions (e.g., coating agents) described herein can include a first group of compounds of Formulas I, II, and/or III (e.g., fatty acids and/or salts or esters thereof) and a second group of compounds of Formulas I, II, and/or III (e.g., fatty acids and/or salts or esters thereof), where each compound of the first group of compounds has a carbon chain length of at least 14, and each compound of the second group of compounds has a carbon chain length of 13 or less, for example in a range of 7 to 13. The first and second groups of compounds can each, for example, include ethyl esters, methyl esters, glyceryl esters (e.g., monoacylglycerides such as 1-monoacylglycerides or 2-monoacylglycerides), sodium salts of fatty acids, potassium salts of fatty acids, calcium salts of fatty acids, magnesium salts of fatty acids, or combinations thereof.
A mass ratio of the fatty acids and/or esters in the first group of compounds to the salts in the first group of compounds can be in any of the ranges given previously (e.g., a range such that the solubility of the coating agent in the solvent is sufficient to allow the desired coating agent concentration to be dissolved, suspended, or dispersed in the solvent). A mass ratio of the first group of compounds (carbon chain length of at least 14) to the second group of compounds (carbon chain length of 13 or less) can be in a range of about 2 to 200, for example about 2 to 100, 2 to 90, 2 to 80, 2 to 70, 2 to 60, 2 to 50, 2 to 40, 2 to 30, 2 to 25, 2 to 20, 2 to 15, 2 to 10, 2.5 to 200, 2.5 to 100, 2.5 to 90, 2.5 to 80, 2.5 to 70, 2.5 to 60, 2.5 to 50, 2.5 to 40, 2.5 to 30, 2.5 to 25, 2.5 to 20, 2.5 to 15, 2.5 to 10, 3 to 200, 3 to 100, 3 to 90, 3 to 80, 3 to 70, 3 to 60, 3 to 50, 3 to 40, 3 to 30, 3 to 25, 3 to 20, 3 to 15, 3 to 10, 4 to 200, 4 to 100, 4 to 90, 4 to 80, 4 to 70, 4 to 60, 4 to 50, 4 to 40, 4 to 30, 4 to 25, 4 to 20, 4 to 15, 4 to 10, 5 to 200, 5 to 100, 5 to 90, 5 to 80, 5 to 70, 5 to 60, 5 to 50, 5 to 40, 5 to 30, 5 to 25, 5 to 20, 5 to 15, or 5 to 10.
As described above, the coating agent can be added to or dissolved, suspended, or dispersed in a solvent to form a suspension, colloid, or solution. The various components of the coating agent (e.g., the compounds of Formula I, the salts of Formula II and/or III, and/or the wetting agents) can be combined prior to being added to the solvent and then added to the solvent together. Alternatively, at least some of the components of the coating agent can be kept separate from other components and can be added to the solvent consecutively (or at separate times).
The concentration of the first group of compounds (compounds of Formula I, II and/or III having a carbon chain length of at least 14) in the solvent/solution/suspension/colloid can, for example, be in a range of about 1 mg/mL to about 200 mg/mL, such as about 1 to 150 mg/mL, 1 to 100 mg/mL, 1 to 90 mg/mL, 1 to 80 mg/mL, 1 to 75 mg/mL, 1 to 70 mg/mL, 1 to 65 mg/mL, 1 to 60 mg/mL, 1 to 55 mg/mL, 1 to 50 mg/mL, 1 to 45 mg/mL, 1 to 40 mg/mL, 2 to 200 mg/mL, 2 to 150 mg/mL, 2 to 100 mg/mL, 2 to 90 mg/mL, 2 to 80 mg/mL, 2 to 75 mg/mL, 2 to 70 mg/mL, 2 to 65 mg/mL, 2 to 60 mg/mL, 2 to 55 mg/mL, 2 to 50 mg/mL, 2 to 45 mg/mL, 2 to 40 mg/mL, 5 to 200 mg/mL, 5 to 150 mg/mL, 5 to 100 mg/mL, 5 to 90 mg/mL, 5 to 80 mg/mL, 5 to 75 mg/mL, 5 to 70 mg/mL, 5 to 65 mg/mL, 5 to 60 mg/mL, 5 to 55 mg/mL, 5 to 50 mg/mL, 5 to 45 mg/mL, 5 to 40 mg/mL, 10 to 200 mg/mL, 10 to 150 mg/mL, 10 to 100 mg/mL, 10 to 90 mg/mL, 10 to 80 mg/mL, 10 to 75 mg/mL, 10 to 70 mg/mL, 10 to 65 mg/mL, 10 to 60 mg/mL, 10 to 55 mg/mL, 10 to 50 mg/mL, 10 to 45 mg/mL, or 10 to 40 mg/mL.
The concentration of wetting agents or second group of compounds of Formula I, II, and/or III (e.g., compounds of Formula I and/or salts of Formula II and/or III having a carbon chain length of 13 or less) in the solvent/solution/suspension/colloid can, for example, be about 0.01 mg/mL to about 20 mg/mL, such as about 0.01 mg/mL to 15 mg/mL, 0.01 mg/mL to 12 mg/mL, 0.01 mg/mL to 10 mg/mL, 0.01 mg/mL to 9 mg/mL, 0.01 mg/mL to 8 mg/mL, 0.01 mg/mL to 7 mg/mL, 0.01 mg/mL to 6 mg/mL, 0.01 mg/mL to 5 mg/mL, 0.1 mg/mL to 20 mg/mL, 0.1 mg/mL to 15 mg/mL, 0.1 mg/mL to 12 mg/mL, 0.1 mg/mL to 10 mg/mL, 0.1 mg/mL to 9 mg/mL, 0.1 mg/mL to 8 mg/mL, 0.1 mg/mL to 7 mg/mL, 0.1 mg/mL to 6 mg/mL, 0.1 mg/mL to 5 mg/mL, 0.5 mg/mL to 20 mg/mL, 0.5 mg/mL to 15 mg/mL, 0.5 mg/mL to 12 mg/mL, 0.5 mg/mL to 10 mg/mL, 0.5 mg/mL to 9 mg/mL, 0.5 mg/mL to 8 mg/mL, 0.5 mg/mL to 7 mg/mL, 0.5 mg/mL to 6 mg/mL, or 0.5 mg/mL to 5 mg/mL.
The composition that is added to the solvent (e.g., the coating agent) can be composed from about 50% to about 99.9% (e.g., about 60%-99.9%, 65%-99.9%, 70%-99.9%, 75%-99.9%, 80%-99.9%, 85%-99.9%, 90%-99.9%, 50%-99%, 60%-99%, 65%-99%, 70%-99%, 75%-99%, 80%-99%, 85%-99%, 90%-99%, 50%-98%, 60%-98%, 65%-98%, 70%-98%, 75%-98%, 80%-98%, 85%-98%, 90%-98%, 50%-96%, 60%-96%, 65%-96%, 70%-96%, 75%-96%, 80%-96%, 85%-96%, 90%-96%, 50%-94%, 60%-94%, 65%-94%, 70%-94%, 75%-94%, 80%-94%, 85%-94%, or 90%-94%) by mass of a first group of compounds of fatty acids, fatty acid esters, fatty acid salts, or combinations thereof (e.g., compounds of Formula I and/or salts of Formula II or Formula III), where optionally each compound of the first group optionally has a carbon chain length of at least 14. In some embodiments, the compounds of the first group are fatty acid esters, e.g., monoacylglycerides.
The composition that is added to the solvent (e.g., the coating agent) can be composed from about 0.1% to about 50% (e.g., about 0.1%-45%, 0.1%-40%, 0.1%-35%, 0.1%-30%, 0.1%-25%, 0.1%-20%, 0.1%-15%, 0.1%-10%, 0.1%-8%, 0.1%-6%, 0.1%-5%, 0.1%-4%, 0.4%-50%, 0.4%-45%, 0.4%-40%, 0.4%-35%, 0.4%-30%, 0.4%-25%, 0.4%-20%, 0.4%-15%, 0.4%-10%, 0.4%-8%, 0.4%-6%, 0.4%-5%, 0.4%-4%, 0.7%-50%, 0.7%-45%, 0.7%-40%, 0.7%-35%, 0.7%-30%, 0.7%-25%, 0.7%-20%, 0.7%-15%, 0.7%-10%, 0.7%-8%, 0.7%-6%, 0.7%-5%, 0.7%-4%, 1%-50%, 1%-45%, 1%-40%, 1%-35%, 1%-30%, 1%-25%, 1%-20%, 1%-15%, 1%-10%, 1%-8%, 1%-6%, 1%-5%, or 1%-4%) by mass of a second group of compounds of fatty acids, fatty acid esters, fatty acid salts, or combinations thereof (e.g., compounds of Formula I and/or salts of Formula II and/or III), where each compound of the second group optionally has a carbon chain length of 13 or less (e.g., a carbon chain length in a range of 7 to 13). The compounds of the second group can function as wetting agents, as previously described.
The composition that is added to the solvent (e.g., the coating agent) can be composed from about 0.1% to about 50% (e.g., about 0.1%-45%, 0.1%-40%, 0.1%-35%, 0.1%-30%, 0.1%-25%, 0.1%-20%, 0.1%-15%, 0.1%-10%, 0.1%-8%, 0.1%-6%, 0.1%-5%, 0.1%-4%, 0.4%-50%, 0.4%-45%, 0.4%-40%, 0.4%-35%, 0.4%-30%, 0.4%-25%, 0.4%-20%, 0.4%-15%, 0.4%-10%, 0.4%-8%, 0.4%-6%, 0.4%-5%, 0.4%-4%, 0.7%-50%, 0.7%-45%, 0.7%-40%, 0.7%-35%, 0.7%-30%, 0.7%-25%, 0.7%-20%, 0.7%-15%, 0.7%-10%, 0.7%-8%, 0.7%-6%, 0.7%-5%, 0.7%-4%, 1%-50%, 1%-45%, 1%-40%, 1%-35%, 1%-30%, 1%-25%, 1%-20%, 1%-15%, 1%-10%, 1%-8%, 1%-6%, 1%-5%, or 1%-4%) by mass of a third group of compounds comprised of salts of compounds of Formula II or Formula III, or fatty acid salts. Each compound of the third group can optionally have a carbon chain length greater than 13. The compounds of the third group can function as emulsifiers and, for example, increase the solubility of the coating agent, as previously described.
Any of the coating solutions/suspensions/colloids described herein can further include an antimicrobial agent, for example ethanol or citric acid. In some implementations, the antimicrobial agent is part of or a component of the solvent. Any of the coating solutions described herein can further include other components or additives such as sodium bicarbonate.
In some implementations, coatings formed from coating agents described herein over agricultural products can be configured to change the surface energy of the agricultural product. Various properties of coatings described herein can be adjusted by tuning the crosslink density of the coating, its thickness, or its chemical composition. This can, for example, be used to control the ripening of postharvest fruit or produce. For example, coatings formed from coating agents that primarily include bifunctional or polyfunctional monomer units can, for example, have higher crosslink densities than those that include monofunctional monomer units. Thus, coatings formed from bifunctional or polyfunctional monomer units can in some cases result in slower rates of ripening as compared to coatings formed from monofunctional monomer units.
In some implementations, one or more wetting agents such as those described above are used to improve the wetting of the surfaces to which the coating solutions/suspensions/colloids are applied, but the wetting agent are not included in the coating solutions/suspensions/colloids. Instead, the wetting agents are added to a second solvent (which can be the same as or different than the solvent to which the coating agent is added) to form a second mixture, and the second mixture is applied to the surface to be coated prior to applying the coating solution/suspension/colloid to the surface. In this case, the second mixture can prime the surface to be coated such that the contact angle of the coating solution/suspension/colloid with the surface is less than it would have otherwise been, thereby improving surface wetting.
Any of the coating agents described herein can further include additional materials that are also transported to the surface with the coating, or are deposited separately and are subsequently encapsulated by the coating (e.g., the coating is formed at least partially around the additional material), or are deposited separately and are subsequently supported by the coating (e.g., the additional material is anchored to the external surface of the coating). Examples of such additional materials can include cells, biological signaling molecules, vitamins, minerals, pigments, aromas, enzymes, catalysts, antifungals, antimicrobials, and/or time-released drugs. The additional materials can be non-reactive with surface of the coated product and/or coating, or alternatively can be reactive with the surface and/or coating.
In some implementations, the coating can include an additive configured, for example, to modify the viscosity, vapor pressure, surface tension, or solubility of the coating. The additive can, for example, be configured to increase the chemical stability of the coating. For example, the additive can be an antioxidant configured to inhibit oxidation of the coating. In some implementations, the additive can reduce or increase the melting temperature or the glass-transition temperature of the coating. In some implementations, the additive is configured to reduce the diffusivity of water vapor, oxygen, CO2, or ethylene through the coating or enable the coating to absorb more ultra violet (UV) light, for example to protect the agricultural product (or any of the other products described herein). In some implementations, the additive can be configured to provide an intentional odor, for example a fragrance (e.g., smell of flowers, fruits, plants, freshness, scents, etc.). In some implementations, the additive can be configured to provide color and can include, for example, a dye or a US Food and Drug Administration (FDA) approved color additive.
Any of the coating agents or coatings formed thereof that are described herein can be flavorless or have high flavor thresholds, e.g. above 500 ppm, and can be odorless or have a high odor threshold. In some embodiments, the materials included in any of the coatings described herein can be substantially transparent. For example, the coating agent, the solvent, and/or any other additives included in the coating can be selected so that they have substantially the same or similar indices of refraction. By matching their indices of refraction, they may be optically matched to reduce light scattering and improve light transmission. For example, by utilizing materials that have similar indices of refraction and have a clear, transparent property, a coating having substantially transparent characteristics can be formed.
The compositions (e.g., coating agents) described herein can be of high purity. For example, the compositions can be substantially free (e.g., be less than 10% by mass, less than 9% by mass, less than 8% by mass, less than 7% by mass, less than 6% by mass, or less than 5%, 4%, 3%, 2%, or 1% by mass) of diglycerides, triglycerides, proteins, polysaccharides, phenols, lignans, aromatic acids, terpenoids, flavonoids, carotenoids, alkaloids, alcohols, alkanes, and/or aldehydes. In some embodiments, the compositions comprise less than 10% (e.g., less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%) by mass of diglycerides. In some embodiments, the compositions comprise less than 10% (e.g., less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%) by mass of triglycerides.
Any of the coatings described herein can be disposed on the external surface of an agricultural product or other substrate using any suitable means. For example, the substrate can be dip-coated in a bath of the coating formulation (e.g., an aqueous or mixed aqueous-organic or organic solution). The deposited coating can form a thin layer on the surface of an agricultural product, which can protect the agricultural product from biotic stressors, water loss, and/or oxidation. In some implementations, the deposited coating can have a thickness of less than 10 microns, less than 9 microns, less than 8 microns, less than 7 microns, less than 6 microns, less than 5 microns, less than 4 microns, less than 3 microns, less than 2 microns, or less than about 1500 nm, and/or the coating can be transparent to the naked eye. For example, the deposited coating can have a thickness of about 10 nm, about 20 nm, about 30 nm, about 40 nm, about 50 nm, about 100 nm, about 150 nm, about 200 nm, about 250 nm, about 300 nm, about 350 nm, about 400 nm, about 450 nm, about 500 nm, about 550 nm, about 600 nm, about 650 nm, about 700 nm, about 750 nm, about 800 nm, about 850 nm, about 900 nm, about 950 nm, 1,000 nm, about 1,100 nm, about 1,200 nm, about 1,300 nm, about 1,400 nm, about 1,500 nm, about 1,600 nm, about 1,700 nm, about 1,800 nm, about 1,900 nm, about 2,000 nm, about 2,100 nm, about 2,200 nm, about 2,300 nm, about 2,400 nm, about 2,500 nm, about 2,600 nm, about 2,700 nm, about 2,800 nm, about 2,900 nm, or about 3,000 nm, inclusive of all ranges therebetween.
In some implementations, the deposited coating can be deposited substantially uniformly over the substrate and can be free of defects and/or pinholes. In some implementations, the dip-coating process can include sequential coating of the agricultural product in baths of coating precursors that can undergo self-assembly or covalent bonding on the agricultural product to form the coating. In some implementations, the coating can be deposited on agricultural products by passing the agricultural products under a stream of the coating solution/suspension/colloid (e.g., a waterfall of the coating solution/suspension/colloid). For example, the agricultural products can be disposed on a conveyor that passes through the stream of the coating solution/suspension/colloid. In some implementations, the coating can be misted, vapor- or dry vapor-deposited on the surface of the agricultural product. In some implementations, the coating solution/suspension/colloid can be mechanically applied to the surface of the product to be coated, for example by brushing it onto the surface. In some embodiments, the coating can be configured to be fixed on the surface of the agricultural product by UV crosslinking or by exposure to a reactive gas, for example oxygen.
In some implementations, the coating solutions/suspensions/colloids can be spray-coated on the agricultural products. Commercially available sprayers can be used for spraying the coating solutions/suspensions/colloids onto the agricultural product. In some implementations, the coating formulation can be electrically charged in the sprayer before spray-coating on to the agricultural product, such that the deposited coating electrostatically and/or covalently bonds to the exterior surface of the agricultural product.
As previously described, the coatings formed from coating agents described herein can be configured to prevent water loss or other moisture loss from the coated portion of the plant, delay ripening, and/or prevent oxygen diffusion into the coated portion of the plant, for example, to reduce oxidation of the coated portion of the plant. The coatings can also serve as a barrier to diffusion of carbon dioxide and/or ethylene into or out of the plant or agricultural product. The coatings can also protect the coated portion of the plant against biotic stressors, such as, for example, bacteria, fungi, viruses, and/or pests that can infest and decompose the coated portion of the plant. Since bacteria, fungi and pests all identify food sources via recognition of specific molecules on the surface of the agricultural product, coating the agricultural products with the coating agent can deposit molecularly contrasting molecules on the surface of the portion of the plant, which can render the agricultural products unrecognizable. Furthermore, the coating can also alter the physical and/or chemical environment of the surface of the agricultural product making the surface unfavorable for bacteria, fungi or pests to grow. The coating can also be formulated to protect the surface of the portion of the plant from abrasion, bruising, or otherwise mechanical damage, and/or protect the portion of the plant from photodegradation. The portion of the plant can include, for example, a leaf, a stem, a shoot, a flower, a fruit, a root, etc.
Any of the coatings described herein can be used to protect any agricultural product. In some embodiments, the coating can be coated on an edible agricultural product, for example, fruits, vegetables, edible seeds and nuts, herbs, spices, produce, meat, eggs, dairy products, seafood, grains, or any other consumable item. In such embodiments, the coating can include components that are non-toxic and safe for consumption by humans and/or animals. For example, the coating can include components that are U.S. Food and Drug Administration (FDA) approved direct or indirect food additives, FDA approved food contact substances, satisfy FDA regulatory requirements to be used as a food additive or food contact substance, and/or is an FDA Generally Recognized as Safe (GRAS) material. Examples of such materials can be found within the FDA Code of Federal Regulations Title 21, located at “http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm”, the entire contents of which are hereby incorporated by reference herein. In some embodiments, the components of the coating can include a dietary supplement or ingredient of a dietary supplement. The components of the coating can also include an FDA approved food additive or color additive. In some embodiments, the coating can include components that are naturally derived, as described herein. In some embodiments, the coating can be flavorless or have a high flavor threshold of below 500 ppm, are odorless or have a high odor threshold, and/or are substantially transparent. In some embodiments, the coating can be configured to be washed off an edible agricultural product, for example, with water.
In some embodiments, the coatings described herein can be formed on an inedible agricultural product. Such inedible agricultural products can include, for example, inedible flowers, seeds, shoots, stems, leaves, whole plants, and the like. In such embodiments, the coating can include components that are non-toxic, but the threshold level for non-toxicity can be higher than that prescribed for edible products. In such embodiments, the coating can include an FDA approved food contact substance, an FDA approved food additive, or an FDA approved drug ingredient, for example, any ingredient included in the FDA's database of approved drugs, which can be found at “http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm”, the entire contents of which are hereby incorporated herein by reference. In some embodiments, the coating can include materials that satisfy FDA requirements to be used in drugs or are listed within the FDA's National Drug Discovery Code Directory, “http://www.accessdata.fda.gov/scripts/cder/ndc/default.cfm”, the entire contents of which are hereby incorporated herein by reference. In some embodiments, the materials can include inactive drug ingredients of an approved drug product as listed within the FDA's database, “http://www.accessdata.fda.gov/scripts/cder/ndc/default.cfm”, the entire contents of which are hereby incorporated herein by reference.
Embodiments of the coatings described herein provide several advantages, including, for example: (1) the coatings can protect the agricultural products from biotic stressors, i.e. bacteria, viruses, fungi, or pests; (2) the coatings can prevent evaporation of water and/or diffusion of oxygen, carbon dioxide, and/or ethylene; (3) coating can help extend the shelf life of agricultural products, for example, post-harvest produce, without refrigeration; (4) the coatings can introduce mechanical stability to the surface of the agricultural products eliminating the need for expensive packaging designed to prevent the types of bruising which accelerate spoilage; (5) use of agricultural waste materials to obtain the coatings can help eliminate the breeding environments of bacteria, fungi, and pests; (6) the coatings can be used in place of pesticides to protect plants, thereby minimizing the harmful impact of pesticides to human health and the environment; (7) the coatings can be naturally derived and hence, safe for human consumption. Since in some cases the components of the coatings described herein can be obtained from agricultural waste, such coatings can be made at a relatively low cost. Therefore, the coatings can be particularly suited for small scale farmers, for example, by reducing the cost required to protect crops from pesticides and reducing post-harvest losses of agricultural products due to decomposition by biotic and/or environmental stressors.
Due to segmentation in the marketplace, the preparation/formation of coating agents or coating solutions/suspensions/colloids and the formation of coatings over substrates from the coating solutions/suspensions/colloids are often carried out by different parties or entities. For example, a manufacturer of compositions such as coating agents described herein (i.e., a first party) can form the compositions by one or more of the methods described herein. The manufacturer can then sell or otherwise provide the resulting composition to a second party, for example a farmer, shipper, distributor, or retailer of produce, and the second party can apply the composition to one or more agricultural products to form a protective coating over the products. Alternatively, the manufacturer can sell or otherwise provide the resulting composition to an intermediary party, for example a wholesaler, who then sells or otherwise provides the composition to a second party such as a farmer, shipper, distributor, or retailer of produce, and the second party can apply the composition to one or more agricultural products to form a protective coating over the products.
In some cases where multiple parties are involved, the first party may optionally provide instructions or recommendations about the composition (i.e., the coating agent), either written or oral, indicating one or more of the following: (i) that the composition is intended to be applied to a product for the purpose of coating or protecting the product, to extend the life of the product, to reduce spoilage of the product, or to modify or improve the aesthetic appearance of the product; (ii) conditions and/or methods that are suitable for applying the compositions to the surfaces of products; and/or (iii) potential benefits (e.g., extended shelf life, reduced rate of mass loss, reduced rate of molding and/or spoilage, etc.) that can result from the application of the composition to a product. While the instructions or recommendations may be supplied by the first party directly with the plant extract composition (e.g., on packaging in which the composition is sold or distributed), the instructions or recommendations may alternatively be supplied separately, for example on a website owned or controlled by the first party, or in advertising or marketing material provided by or on behalf of the first party.
In view of the above, it is recognized that in some cases, a party that manufactures compositions (i.e., coating agents) or coating solutions/suspensions/colloids according to one or more methods described herein (i.e., a first party) may not directly form a coating over a product from the composition, but can instead direct (e.g., can instruct or request) a second party to form a coating over a product from the composition. That is, even if the first party does not coat a product by the methods and compositions described herein, the first party may still cause the coating agent or solution to be applied to the product to form a protective coating over the product by providing instructions or recommendations as described above. Accordingly, as used herein, the act of applying a coating agent or solution/suspension/colloid to a product (e.g., a plant or agricultural product) also includes directing or instructing another party to apply the coating agent or solution to the product, thereby causing the coating agent or solution to be applied to the product.
The following examples describe effects of various coating agents and solutions/suspensions/colloids on various substrates, as well as characterization of some of the various coating agents and solutions/suspensions/colloids. These examples are only for illustrative purposes and are not meant to limit the scope of the present disclosure. In each of the examples below, all reagents and solvents were purchased and used without further purification unless specified.
In order to form the coatings, the finger limes were placed in bags, and the solution containing the composition was poured into the bag. The bag was then sealed and lightly agitated until the entire surface of each finger lime was wet. The finger limes were then removed from the bag and allowed to dry on drying racks. The finger limes were kept under ambient room conditions at a temperature in the range of about 23° C.-27° C. and humidity in the range of about 40%-55% while they dried and for the entire duration of the time they were tested.
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Nine solutions using combinations of long chain fatty acid esters were prepared to examine the effects of various coating agent compositions on the mass loss rate of avocados treated with a solution composed of the coating agent dissolved in a solvent to form a coating over the avocados. Each solution was composed of the coating agents described below dissolved in ethanol at a concentration of 5 mg/mL.
The first solution contained MA-1G and PA-2G combined at a molar ratio of 1:3. The second solution contained MA-1G and PA-2G combined at a molar ratio of 1:1. The third solution contained MA-1G and PA-2G combined at a molar ratio of 3:1. The fourth solution contained PA-1G and PA-2G combined at a molar ratio of 3:1. The fifth solution contained PA-1G and PA-2G combined at a molar ratio of 1:1. The sixth solution contained PA-1G and PA-2G combined at a molar ratio of 1:3. The seventh solution contained SA-1G and PA-2G combined at a molar ratio of 1:3. The eighth solution contained SA-1G and PA-2G combined at a molar ratio of 1:1. The ninth solution contained SA-1G and PA-2G combined at a molar ratio of 3:1.
Avocados were harvested simultaneously and divided into nine groups of 30 avocados, each of the groups being qualitatively identical (i.e., all groups had avocados of approximately the same average size and quality). In order to form the coatings, the avocados were each individually dipped in one of the solutions, with each group of 30 avocados being treated with the same solution. The avocados were then placed on drying racks and allowed to dry under ambient room conditions at a temperature in the range of about 23° C.-27° C. and relative humidity in the range of about 40%-55%. The avocados were all held at these same temperature and humidity conditions for the entire duration of time they were tested.
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As shown, the mass loss factor tended to increase as the carbon chain length of the fatty acid ester was increased. For example, all mixtures for which the carbon chain length of the ester was greater than 13 resulted in a mass loss factor greater than 1.2, all mixtures for which the carbon chain length of the ester was greater than 15 resulted in a mass loss factor greater than 1.35, and all mixtures for which the carbon chain length of the ester was greater than 17 resulted in a mass loss factor great than 1.6.
Two solutions were prepared by dissolving a coating agent formed of PA-2G and PA-1G mixed at a mass ratio of 75:25 in substantially pure ethanol. For the first solution, the coating agent was dissolved in the ethanol at a concentration of 10 mg/mL, and for the second solution, the coating agent was dissolved in the ethanol at a concentration of 20 mg/mL.
Blueberries were harvested simultaneously and divided into three groups of 60 blueberries each, each of the groups being qualitatively identical (i.e., all groups had blueberries of approximately the same average size and quality). The first group was a control group of untreated blueberries, the second group was treated with the 10 mg/mL solution, and the third group was treated with the 20 mg/mL solution.
To treat the blueberries, each blueberry was picked up with a set of tweezers and individually dipped in the solution for approximately 1 second, after which the blueberry was placed on a drying rack and allowed to dry. The blueberries were kept under ambient room conditions at a temperature in the range of 23° C.-27° C. and humidity in the range of 40%-55% while they dried and for the entire duration of the time they were tested. Mass loss was measured by carefully weighing the blueberries each day, where the reported percent mass loss was equal to the ratio of mass reduction to initial mass.
Each bar in the graph represents a group of 90 lemons. All coatings were formed by dipping the lemons in their associated suspension, placing the lemons on drying racks, and allowing the lemons to dry under ambient room conditions at a temperature in the range of about 23° C.-27° C. and humidity in the range of about 40%-55%. The lemons were held at these same temperature and humidity conditions for the entire duration of the time they were tested. As seen in
Each bar in the graph represents a group of 60 lemons. All coatings were formed by dipping the lemons in their associated solution, placing the lemons on drying racks, and allowing the lemons to dry under ambient room conditions at a temperature in the range of about 23° C.-27° C. and humidity in the range of about 40%-55%. The lemons were held at these same temperature and humidity conditions for the entire duration of the time they were tested. As seen in
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While various compositions and methods have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where methods and steps described above indicate certain events occurring in certain order, ordering of steps may be modified, and such modification are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. The various implementations have been particularly shown and described, but it will be understood that various changes in form and details may be made. Accordingly, other implementations are within the scope of the following claims.
This application claims the benefit of U.S. Provisional Application 62/727,501, filed Sep. 5, 2018, and incorporated herein for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62727501 | Sep 2018 | US |
