METHOD OF PROTECTING ITEMS FROM DEGRADATION AND DECOMPOSITION
20200383343 ยท 2020-12-10
Inventors
Cpc classification
B05B7/1686
PERFORMING OPERATIONS; TRANSPORTING
B05D7/24
PERFORMING OPERATIONS; TRANSPORTING
A23P20/15
HUMAN NECESSITIES
B05D7/534
PERFORMING OPERATIONS; TRANSPORTING
A23B7/16
HUMAN NECESSITIES
B05D1/30
PERFORMING OPERATIONS; TRANSPORTING
International classification
A23B7/16
HUMAN NECESSITIES
A23P20/15
HUMAN NECESSITIES
B05D7/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
Methods of forming a protective coating on a surface of one or more substrates. The methods include providing a mixture including a coating agent in a solvent, forming a fog from the mixture, allowing the fog to contact the outer surface of the one or more substrates so that a portion of the mixture accumulates on at least a portion of the surface of the one or more substrates. The solvent from the mixture is then at least partially removed from the surface of the one or more substrates, e.g., by evaporation or forced convection, causing a protective coating to be formed from the coating agent on at least a part of the surfaces of the one or more substrates. The protective coating can, for example, protect at least to some extent the substrates from biotic or abiotic stressors such as mass or moisture loss, oxidation, mold, fungi, or infestation.
Claims
1. A method of forming a protective coating on a surface of a substrate, comprising: forming a fog comprising droplets of a mixture, the mixture comprising a coating agent in a solvent; causing the fog to contact at least a portion of the surface of the substrate so that a portion of the mixture accumulates on at least a portion of the surface of the substrate; and at least partially removing the solvent from the mixture on the surface of the substrate, thereby forming a protective coating from the coating agent on at least a portion of the surface of the substrate.
2. The method of claim 1, wherein the fog is formed by a method comprising: (i) heating the mixture to form a vapor; and (ii) cooling the vapor to form the fog comprising droplets of the mixture.
3. The method of claim 1, wherein the substrate is perishable.
4. The method of claim 1, wherein the substrate is selected from a plant or a plant comprising pre-harvested produce.
5. The method of claim 1, wherein the substrate comprises produce.
6. The method of claim 1, wherein the substrate is maintained within the fog for less than 2 minutes.
7. The method of any of claim 1, wherein the coating agent comprises a compound of Formula I, wherein Formula I is: ##STR00028## wherein: R is selected from H, -glyceryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, heteroaryl, or a cationic moiety, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more groups selected from halogen (e.g., Cl, Br, or I), hydroxyl, nitro, CN, NH.sub.2, SH, SR.sup.15, OR.sup.14, NR.sup.14R.sup.15, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl; R.sup.1, R.sup.2, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are each independently, at each occurrence, H, (CO)R.sup.14, (CO)H, (CO)OH, (CO)OR.sup.14, (CO)O(CO)R.sup.14, O(CO)R.sup.14, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; R.sup.3, R.sup.4, R.sup.7, and R.sup.8 are each independently, at each occurrence, H, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; or R.sup.3 and R.sup.4 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or R.sup.7 and R.sup.8 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; R.sup.14 and R.sup.15 are each independently, at each occurrence, H, aryl, heteroaryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 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 [0080] r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
8. A method of forming a protective coating on a surface of a substrate, comprising: forming a first fog comprising droplets of a first mixture, the first mixture comprising a first coating agent in a first solvent; causing the first fog to contact at least a portion of the surface of the substrate so that a portion of the first mixture accumulates on at least a portion of the surface of the substrate; at least partially removing the first solvent from the first mixture on the surface of the substrate, thereby forming a first protective coating from the first coating agent on at least part of the surface of the substrate; forming a second fog comprising droplets of a second mixture, the second mixture comprising a second coating agent in a second solvent; causing the second fog to contact at least a portion of one or both of the first protective coating on the surface of the substrate or at least a portion of the surface of the substrate that was incompletely coated with the first protective coating so that a portion of the second mixture accumulates on one or both of the first protective coating on the surface of the substrate or at least a portion of the surface of the substrate that was incompletely coated with the first protective coating; and at least partially removing the second solvent from the second mixture on one or both of the first protective coating on the surface of the substrate or the surface of the substrate that was incompletely coated with the first protective coating, thereby forming a second protective coating from the second coating agent on at least part of one or both of the first protective coating on the surface of the substrate or the surface of the substrate that was incompletely coated with the first protective coating.
9. The method of claim 8, wherein the first mixture is the same as the second mixture.
10. The method of claim 8, wherein the first mixture is different from the second mixture.
11. The method of claim 8, wherein the first fog is formed by a method comprising: (i) heating the first mixture to form a vapor; and (ii) cooling the vapor to form the first fog comprising droplets of the first mixture.
12. The method of claim 8, wherein the second fog is formed by a method comprising: (i) heating the second mixture to form a vapor; and (ii) cooling the vapor to form the second fog comprising droplets of the first mixture.
13. The method of claim 8, wherein the first fog is applied to the substrate for about the same amount of time as the second fog.
14. The method of claim 8, wherein the first fog is applied to the substrate for a different amount of time than the second fog.
15. The method of any of claim 8, wherein the first and second coating agent independently comprise a compound of Formula I, wherein Formula I is: ##STR00029## wherein: R is selected from H, -glyceryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, heteroaryl, or a cationic moiety, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more groups selected from halogen (e.g., Cl, Br, or I), hydroxyl, nitro, CN, NH.sub.2, SH, SR.sup.15, OR.sup.14, NR.sup.14R.sup.15, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl; R.sup.1, R.sup.2, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are each independently, at each occurrence, H, (CO)R.sup.14, (CO)H, (CO)OH, (CO)OR.sup.14, (CO)O(CO)R.sup.14, O(CO)R.sup.14, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; R.sup.3, R.sup.4, R.sup.7, and R.sup.8 are each independently, at each occurrence, H, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; or R.sup.3 and R.sup.4 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or R.sup.7 and R.sup.8 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; R.sup.14 and R.sup.15 are each independently, at each occurrence, H, aryl, heteroaryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 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.
16. A method of forming a protective coating on the surfaces of a plurality of items in a container, comprising: causing a fog comprising droplets of a mixture to enter the container through one or more openings in the container, the mixture comprising a coating agent in a solvent; wherein the fog disperses through the interior of the container to contact the surface of the plurality of items so that a portion of the mixture accumulates on at least a portion of the surfaces of the plurality of items, thereby causing a protective coating to be formed from the coating agent on at least a portion of the surfaces of the plurality of items.
17. The method of any of claim 16, wherein the fog is formed by a method comprising: (i) heating the mixture to form a vapor; and (ii) cooling the vapor to form the fog comprising droplets of the mixture.
18. The method of claim 16, wherein the items are perishable.
19. The method of claim 16, wherein the items comprise produce.
20. The method of claim 16, wherein the items are maintained within the fog for less than 2 minutes.
21. The method of claim 16, wherein causing the protective coating to be formed from the coating agent on at least a portion of the surfaces of the plurality of items comprises at least partially removing the solvent from the mixture on the surfaces of the plurality of items.
22. The method of claim 16, wherein causing the protective coating to be formed from the coating agent on at least a portion of the surfaces of the plurality of items comprises cooling or drying the plurality of items via convection through at least one of the openings in the container.
23. The method of any of claim 16, wherein the coating agent comprises a compound of Formula I, wherein Formula I is: ##STR00030## wherein: R is selected from H, -glyceryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, heteroaryl, or a cationic moiety, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more groups selected from halogen (e.g., Cl, Br, or I), hydroxyl, nitro, CN, NH.sub.2, SH, SR.sup.15, OR.sup.14, NR.sup.14R.sup.15, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl; R.sup.1, R.sup.2, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are each independently, at each occurrence, H, (CO)R.sup.14, (CO)H, (CO)OH, (CO)OR.sup.14, (CO)O(CO)R.sup.14, O(CO)R.sup.14, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; R.sup.3, R.sup.4, R.sup.7, and R.sup.8 are each independently, at each occurrence, H, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; or R.sup.3 and R.sup.4 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or R.sup.7 and R.sup.8 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; R.sup.14 and R.sup.15 are each independently, at each occurrence, H, aryl, heteroaryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 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 [0081] r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
24. A method of forming a protective coating on the surfaces of a plurality of items, comprising: forming a fog in an enclosure, the fog comprising droplets of a mixture, the mixture comprising a coating agent in a solvent; after at least partially forming the fog, moving the plurality of items into the enclosure, thereby causing the fog to contact at least a portion of the surface of the plurality of items so that a portion of the mixture accumulates on at least a portion of the surfaces of the plurality of items; and causing the solvent to be at least partially removed from the mixture on the surface of the plurality of items, thereby forming the protective coating from the coating agent on at least a portion of the surface of the plurality of items.
25. The method of claim 24, wherein the fog is formed by a method comprising: (i) heating the mixture to form a vapor; and (ii) cooling the vapor to form the fog comprising droplets of the mixture.
26. The method of claim 24, wherein the items are perishable.
27. The method of claim 24, wherein the items comprise produce.
28. The method of claim 24, wherein the items are maintained within the fog for less than 2 minutes.
29. The method of any of claim 24, wherein the coating agent comprises a compound of Formula I, wherein Formula I is: ##STR00031## wherein: R is selected from H, -glyceryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, heteroaryl, or a cationic moiety, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more groups selected from halogen (e.g., Cl, Br, or I), hydroxyl, nitro, CN, NH.sub.2, SH, SR.sup.15, OR.sup.14, NR.sup.14R.sup.15, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl; R.sup.1, R.sup.2, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are each independently, at each occurrence, H, (CO)R.sup.14, (CO)H, (CO)OH, (CO)OR.sup.14, (CO)O(CO)R.sup.14, O(CO)R.sup.14, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; R.sup.3, R.sup.4, R.sup.7, and R.sup.8 are each independently, at each occurrence, H, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; or R.sup.3 and R.sup.4 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or R.sup.7 and R.sup.8 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; R.sup.14 and R.sup.15 are each independently, at each occurrence, H, aryl, heteroaryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 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 [0082] r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0018]
[0019]
[0020]
[0021]
[0022]
[0023]
[0024]
[0025]
[0026]
[0027] Like numerals in the figures represent like elements.
DETAILED DESCRIPTION
[0028] Protective coatings can be used in a variety of applications to protect items from mechanical damage, degradation, decomposition, spoilage, and as a barrier to water and gas transfer into or out of the items. In the case of perishable items such as harvested produce, edible coatings have been used to increase the shelf life by reducing both the rate of water loss from the items and the rate of oxygen diffusion into the items. The coatings can be deposited on the surfaces of the items by first adding the constituents of the coating (herein a coating agent) to a solvent to form a mixture (e.g., a solution, a suspension, a colloid or an emulsion), then applying the mixture to the surfaces of the items, and finally removing the solvent (e.g., by evaporation or forced convection), thereby allowing a coating to form from the coating agent on the surfaces of the items.
[0029] Described herein are processes for depositing protective coatings that allow for increased coverage of the coated substrates, avoid damage that can be caused by overexposure to solvent, and are compatible with a number of configurations that items such as produce are packaged into for distribution. In each of the processes, a fog is formed from a mixture which includes a coating agent in a solvent, and the droplets of the fog are applied to the surface of one or more substrates. As used herein, a fog refers to a collection of droplets that have an average diameter of less than about 150 microns. In particular, droplets of a fog may be sufficiently small that they are effectively suspended in the atmosphere and take some time to settle towards the ground under the influence of gravity. This allows droplets of a fog to diffuse through small or narrow openings before gravity pulls the droplets towards the earth, and can thereby result in improved surface coverage as compared to conventional spray coating methods. For example, a fog that is applied into a container containing a plurality of substrates can diffuse through openings between the substrates and eventually settle on substrate surfaces that would typically not be accessible via a conventional spray.
[0030] Any of the fogs described herein can be formed as either a wet fog or a dry fog. A wet fog is formed of larger droplets than a dry fog. For example, a wet fog may typically contain droplets having an average diameter between about 25 and 100 microns (and in some embodiments about 30 microns), whereas a dry fog may typically contain droplets having an average diameter between about 5 and 20 microns (and in some embodiments, about 10 microns). In some cases, it may be preferable that the fog be a dry fog or be formed of droplets having an average diameter of at least 5 microns, at least 10 microns, at least 15 microns, or at least 20 microns. When a dry fog is used and/or when the droplets are too small, in some cases the time required to achieve sufficient coverage of the substrate surface can be long. When droplets of the fog are sufficiently large and/or the fog is sufficiently dense, sufficient coverage of the substrate can be achieved if the substrate is maintained within the fog for less than 3 minutes, less than 2 minutes, less than 90 seconds, less than 75 seconds, less than 1 minute, less than 50 seconds, less than 40 seconds, or less than 30 seconds.
[0031] Any of the fogs (wet and dry fogs) formed from mixtures described herein (e.g., a solution, suspension, colloid, or emulsion including a coating agent in a solvent) can be formed by the following thermal fogging method. The mixture contained within a fluid tank is forced through a high temperature heat exchanger by a pump, for example, a high-pressure pump, causing the mixture to vaporize. The heat exchanger can be held at a temperature of at least 150 C., at least 200 C., at least 250 C., or at least 300 C. This vapor is then emitted into the atmosphere. When the vapor comes into contact with the relatively cooler atmosphere and begins to expand, it condenses into the small droplets that make up the fog. Other thermal and non-thermal methods recognizable to those skilled in the art can also be used to form the fog, including, but not limited to ultrasonic fogging, or the use of a rotating atomizer, or pulse jet thermal fogger.
[0032]
[0033]
[0034] The method 200 of
[0035] The fogging methods described herein for forming protective coatings over items and substrates can be useful and advantageous for applying coatings to a plurality of substrates in a container (e.g., produce in a reefer or other shipping container, produce contained in a modified atmospheric package, or produce packaged in a box or other container for shipping). For example, rather than removing the items from the container in order to apply the coating mixture to the items, a fog including droplets of the mixture can be directed into the container, e.g., through an opening in the container. The fog then diffuses through openings between adjacent substrates to contact a majority of the exposed surfaces of substrates within the container.
[0036] In view of the above, a method 300 for forming a protective coating over a plurality of items in a container is illustrated in
[0037] In some implementations, one or more of the fogs described herein is formed in an enclosure, and one or more items to be coated is then passed through the enclosure, thereby allowing droplets of the fog to at least partially cover the surface of the items as they pass through the enclosure. For example, items on a conveyor system (or in crates being moved via a conveyor system) can pass through an enclosed area in which the fog is formed, such that droplets of the fog are applied to the surfaces of the items.
[0038] In view of the above, another method 400 for forming a protective coating over a plurality of items is illustrated in
[0039] In some embodiments at least 10% by mass of the solvent is removed from the surface of the items and/or substrate, such as, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% by mass. The percent by mass of the solvent that has been removed can readily be determined using methods known to those skilled in the art. For example, the percent by mass of solvent removed can be determined according to the equation
wherein M.sub.x is the mass of the substrate at time x, M.sub.u is the mass of the uncoated substrate, and M.sub.c is the mass of the coated substrate immediately after it has been coated. Additionally, the percent of the solvent that has been removed from the surface of the substrate can alternatively be monitored using visual techniques, such as, for example, infrared spectroscopy, wherein the peaks in the spectrum attributable to the solvent, e.g., OH stretching peaks characteristic of water or an alcohol, are monitored over time.
[0040] The fogging methods described herein can also be advantageous for forming protective coatings on the surfaces of pre-harvested produce, because the fog can disperse through openings around the pre-harvested produce to improve coverage of the protective coating on the outer surfaces of the pre-harvested produce. A method of forming a protective coating over pre-harvested produce is illustrated in
[0041] The pre-harvest produce can subsequently be harvested after the protective coating has been applied using the fogging methods described herein. Once the produce is harvested, a second protective coating can, if desired, be applied to the surface of the produce using the fogging methods described herein, or by more traditional spraying, misting or brushing a mixture including a coating agent, or by dipping the substrate into a mixture comprising a coating agent as described herein. Subsequent removal of at least a portion of the solvent from the mixture results in a second protective coating formed from the coating agent on at least a portion of the surface of the harvested produce (or on the surface of its pre-harvest coating).
[0042] For any of the fogging methods described herein for forming coatings, including those shown in
[0043] The fogging methods described herein can also be combined with other methods to form coatings on the surface of a substrate. For example, a base layer of the protective coatings according to this disclosure can be applied using the fogging methods described herein. Additional layers of the protective coating can then be applied to the surface of the substrate using the fogging methods described herein, or by more traditional methods, including, but not limited to, spraying, misting or brushing a mixture comprising a coating agent as described herein on the surface of the substrate, or dipping the substrate in a mixture comprising a coating agent. Alternatively, the fogging methods described herein may be used to reinforce a protective coating, preferably applied by a fogging method of this disclosure, that is already present on the surface of the substrate. For example, a substrate having a protective coating as described herein can undergo a second or subsequent treatment with a coating mixture as described herein using the fogging methods of this disclosure. For example, the fogging method described herein can serve to reinforce coatings that were applied to a substrate previously but have begun to experience wear and tear over time, thereby extending the beneficial effects of the protective coatings.
[0044] The droplets of any of the fogs described herein can, for example, have an average diameter of less than 100 microns, less than 95 microns, less than 90 microns, less than 85 microns, less than 80 microns, less than 75 microns, less than 70 microns, less than 65 microns, less than 60 microns, less than 55 microns, less than 50 microns, less than 45 microns, less than 40 microns, less than 35 microns, less than 30 microns, less than 25 microns, less than 20 microns, less than 15 microns, less than 10 microns, less than 5 microns, between 1 and 100 microns, between 1 and 95 microns, between 1 and 90 microns, between 1 and 85 microns, between 1 and 80 microns, between 1 and 75 microns, between 1 and 70 microns, between 1 and 65 microns, between 1 and 60 microns, between 1 and 55 microns, between 1 and 50 microns, between 1 and 45 microns, between 1 and 40 microns, between 1 and 35 microns, between 1 and 30 microns, between 1 and 25 microns, between 1 and 20 microns, between 1 and 15 microns, between 1 and 10 microns, between 1 and 5 microns, between 5 and 100 microns, between 5 and 95 microns, between 5 and 90 microns, between 5 and 85 microns, between 5 and 80 microns, between 5 and 75 microns, between 5 and 70 microns, between 5 and 65 microns, between 5 and 60 microns, between 5 and 55 microns, between 5 and 50 microns, between 5 and 45 microns, between 5 and 40 microns, between 5 and 35 microns, between 5 and 30 microns, between 5 and 25 microns, between 5 and 20 microns, between 5 and 15 microns, between 5 and 10 microns, between 25 and 100 microns, between 25 and 95 microns, between 25 and 90 microns, between 25 and 85 microns, between 25 and 80 microns, between 25 and 75 microns, between 25 and 70 microns, between 25 and 65 microns, between 25 and 60 microns, between 25 and 55 microns, between 25 and 50 microns, between 25 and 45 microns, or between 25 and 40 microns.
[0045] In some embodiments, contacting the surface of one or more substrates with a fog according to this disclosure using the methods described herein results in a protective coating that covers 50 to 100% of the surface of the one or more substrates. For example, in some embodiments the protective coating described herein covers 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% of the surface of the substrate.
[0046] The coating agent can be any compound or combination of compounds that can form a protective coating on at least part of the surface of the substrate via the methods described above. The coating agent can be formulated such that the resulting coating protects at least to some extent 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 at least to some extent the substrate from oxidizing and/or from losing water via transpiration/osmosis/evaporation. The coating agent can additionally or alternatively be formulated such that the resulting coating provides, at least to some extent, a barrier to CO.sub.2, ethylene and/or other gas transfer. 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 and have no taste. 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).
[0047] The coating agent in any of the mixtures described herein can, for example, include fatty acids and/or salts or esters thereof. In some implementations, the coating agent includes monoacylglycerides (e.g., 1-monoacylglycerides or 2-monoacylglycerides). In some embodiments, the coating agent includes at least one of monomers, oligomers, fatty acids, esters, amides, amines, thiols, carboxylic acids, ethers, aliphatic waxes, alcohols, or salts (organic or inorganic salts). The monomers, oligomers, fatty acids, esters, amides, amines, thiols, carboxylic acids, ethers, aliphatic waxes, alcohols, salts, or combinations thereof can, for example, be derived from plant matter such as cutin.
[0048] Coating agents including fatty acids (e.g., palmitic acid, stearic acid, myristic acid, and/or other fatty acids) 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 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. Any of the coating agents herein can include any of the compounds listed above.
[0049] In some implementations, the coating agent includes one or more compounds of Formula I, wherein Formula I is:
##STR00001##
[0050] wherein:
[0051] R is selected from H, -glyceryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, heteroaryl, or a cationic moiety, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more groups selected from halogen (e.g., Cl, Br, or I), hydroxyl, nitro, CN, NH.sub.2, SH, SR.sup.15, OR.sup.14, NR.sup.14R.sup.15, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl;
[0052] R.sup.1, R.sup.2, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are each independently, at each occurrence, H, (CO)R.sup.14, (CO)H, (CO)OH, (CO)OR.sup.14, (CO)O(CO)R.sup.14, O(CO)R.sup.14, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen;
[0053] R.sup.3, R.sup.4, R.sup.7, and R.sup.8 are each independently, at each occurrence, H, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; or
[0054] R.sup.3 and R.sup.4 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or
[0055] R.sup.7 and R.sup.8 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle;
[0056] R.sup.14 and R.sup.15 are each independently, at each occurrence, H, aryl, heteroaryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl;
[0057] the symbol represents a single bond or a cis or trans double bond;
[0058] n is 0, 1, 2, 3, 4, 5, 6, 7 or 8;
[0059] m is 0, 1, 2 or 3;
[0060] q is 0, 1, 2, 3, 4 or 5; and
[0061] r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
[0062] In some embodiments, R is selected from H, CH.sub.3, or CH.sub.2CH.sub.3. In some embodiments, R is selected from H, -glyceryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more C.sub.1-C.sub.6 alkyl or hydroxyl. In some embodiments, R is a cationic moiety. The compounds of Formula I can include salts (e.g., when R is a cationic moiety), for example sodium salts such as SA-Na, PA-Na, or MA-Na, potassium salts such as SA-K, PA-K, or MA-K, calcium salts such as SA-Ca, PA-Ca, or MA-Ca, or magnesium salts such as SA-Mg, PA-Mg, or MA-Mg.
[0063] In some embodiments, the coating agent comprises monoacylglycerides (e.g., 1-monoacylglycerides or 2-monoacylglycerides). The difference between a 1-monoacylglyceride and a 2-monoacylglyceride is the point of connection of the glyceryl ester. Accordingly, in some embodiments, the coating agent comprises compounds of the Formula I-A (e.g., 2-monoacylglycerides):
##STR00002##
[0064] wherein:
[0065] each R.sup.a is independently H or C.sub.1-C.sub.6 alkyl;
[0066] each R.sup.b is independently selected from H, C.sub.1-C.sub.6 alkyl, or OH;
[0067] R.sup.1, R.sup.2, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are each independently, at each occurrence, H, (CO)R.sup.14, (CO)H, (CO)OH, (CO)OR.sup.14, (CO)O(CO)R.sup.14, O(CO)R.sup.14, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen;
[0068] R.sup.3, R.sup.4, R.sup.7, and R.sup.8 are each independently, at each occurrence, H, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; or
[0069] R.sup.3 and R.sup.4 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or
[0070] R.sup.7 and R.sup.8 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle;
[0071] R.sup.14 and R.sup.15 are each independently, at each occurrence, H, aryl, heteroaryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl;
[0072] the symbol represents a single bond or a cis or trans double bond;
[0073] n is 0, 1, 2, 3, 4, 5, 6, 7 or 8;
[0074] m is 0, 1, 2 or 3;
[0075] q is 0, 1, 2, 3, 4 or 5; and
[0076] r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
[0077] In some embodiments, the coating agent comprises compounds of the Formula I-B (e.g., 1-monoacylglycerides):
##STR00003##
[0078] wherein:
[0079] each R.sup.a is independently H or C.sub.1-C.sub.6 alkyl;
[0080] each R.sup.b is independently selected from H, C.sub.1-C.sub.6 alkyl, or OH;
[0081] R.sup.1, R.sup.2, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are each independently, at each occurrence, H, (CO)R.sup.14, (CO)H, (CO)OH, (CO)OR.sup.14, (CO)O(CO)R.sup.14, O(CO)R.sup.14, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen;
[0082] R.sup.3, R.sup.4, R.sup.7, and R.sup.8 are each independently, at each occurrence, H, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; or
[0083] R.sup.3 and R.sup.4 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or
[0084] R.sup.7 and R.sup.8 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle;
[0085] R.sup.14 and R.sup.15 are each independently, at each occurrence, H, aryl, heteroaryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl;
[0086] the symbol represents a single bond or a cis or trans double bond;
[0087] n is 0, 1, 2, 3, 4, 5, 6, 7 or 8;
[0088] m is 0, 1, 2 or 3;
[0089] q is 0, 1, 2, 3, 4 or 5; and
[0090] r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
[0091] Any of the coating agents used in mixtures herein can include one or more of the following fatty acid compounds:
##STR00004## ##STR00005## ##STR00006##
[0092] Any of the coating agents used in mixtures herein can include one or more of the following fatty acid methyl ester compounds:
##STR00007## ##STR00008## ##STR00009##
[0093] Any of the coating agents used in mixtures herein can include one or more of the following fatty acid ethyl ester compounds:
##STR00010## ##STR00011## ##STR00012##
[0094] Any of the coating agents used in mixtures herein can include one or more of the following fatty acid 2-glyceryl ester compounds:
##STR00013## ##STR00014## ##STR00015## ##STR00016##
[0095] Any of the coating agents used in mixtures herein can include one or more of the following fatty acid 1-glyceryl ester compounds:
##STR00017## ##STR00018## ##STR00019## ##STR00020## ##STR00021##
[0096] The coating agents herein can include one or more of the following fatty acid salts, 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:
##STR00022## ##STR00023## ##STR00024## ##STR00025##
where in some embodiments n is 1, 2, or 3.
[0097] The solvent to which the coating agent is added to form the mixture, e.g., a solution, suspension, emulsion, or colloid, can be 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, an alcohol, any other suitable solvent, or a combination thereof. The resulting mixture can be suitable for forming coatings on perishable items such as agricultural products. 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.
[0098] While a number of the solvents above (particularly water and ethanol) can be safely and effectively used in mixtures 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 less expensive 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 mixtures described herein, the solvent or mixture 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 mixture 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.
[0099] 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 or the ability of the edible product to be consumed.
[0100] In some embodiments, organic salts (e.g., compounds of Formula I where R is a cationic moiety) are added to the coating agent to 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 should 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.
[0101] The concentration of the coating agent in the mixture, e.g., solvent, solution, suspension, colloid, or emulsion, 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.
[0102] Any of the mixtures 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 mixtures described herein can further include other components or additives such as sodium bicarbonate.
[0103] 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.
[0104] Any of the coating agents described herein can further include additional materials that are also transported to the surface with the coating-containing fogs, 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.
[0105] In some implementations, the mixture that the coating is derived from 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, CO.sub.2, 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.
[0106] 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.
[0107] The compositions of 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 coating agents 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 coating agents comprise less than 10% (e.g., less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%) by mass of triglycerides.
[0108] In some implementations, the deposited coating can have a thickness of less than about 1500 nm, such that the coating is 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, or about 1,500 nm, inclusive of all ranges therebetween. The coatings can also be thick enough to at least partially protect the substrate or to provide a sufficient barrier to the transfer of water, oxygen, and/or other gases to provide that protection. For example, the protective coating can have a thickness of at least 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.
[0109]
[0110]
EXEMPLARY EMBODIMENTS
[0111] Some exemplary embodiments of this disclosure include:
1. A method of forming a protective coating on a surface of a substrate, comprising:
[0112] forming a fog comprising droplets of a mixture, the mixture comprising a coating agent in a solvent;
[0113] causing the fog to contact at least a portion of the surface of the substrate so that a portion of the mixture accumulates on at least a portion of the surface of the substrate; and
[0114] at least partially removing the solvent from the mixture on the surface of the substrate, thereby forming a protective coating from the coating agent on at least a portion of the surface of the substrate.
2. The method of embodiment 1, wherein the substrate is perishable.
3. The method of embodiment 1, wherein the substrate is selected from a plant or a plant comprising pre-harvested produce.
4. The method of embodiment 1, wherein the substrate comprises produce.
5. The method of embodiment 1, wherein the substrate is maintained within the fog for less than 2 minutes.
6. A method of forming a protective coating on a surface of a substrate, comprising:
[0115] forming a first fog comprising droplets of a first mixture, the first mixture comprising a first coating agent in a first solvent;
[0116] causing the first fog to contact at least a portion of the surface of the substrate so that a portion of the first mixture accumulates on at least a portion of the surface of the substrate;
[0117] at least partially removing the first solvent from the first mixture on the surface of the substrate, thereby forming a first protective coating from the first coating agent on at least part of the surface of the substrate;
[0118] forming a second fog comprising droplets of a second mixture, the second mixture comprising a second coating agent in a second solvent;
[0119] causing the second fog to contact at least a portion of one or both of the first protective coating on the surface of the substrate or at least a portion of the surface of the substrate that was incompletely coated with the first protective coating so that a portion of the second mixture accumulates on one or both of the first protective coating on the surface of the substrate or at least a portion of the surface of the substrate that was incompletely coated with the first protective coating; and
[0120] at least partially removing the second solvent from the second mixture on one or both of the first protective coating on the surface of the substrate or the surface of the substrate that was incompletely coated with the first protective coating, thereby forming a second protective coating from the second coating agent on at least part of one or both of the first protective coating on the surface of the substrate or the surface of the substrate that was incompletely coated with the first protective coating.
7. The method of embodiment 6, wherein the first mixture is the same as the second mixture.
8. The method of embodiment 6, wherein the first mixture is different from the second mixture.
9. The method of embodiment 6, wherein the first fog is applied to the substrate for about the same amount of time as the second fog.
10. The method of embodiment 6, wherein the first fog is applied to the substrate for a different amount of time than the second fog.
11. A method of forming a protective coating on the surfaces of a plurality of items in a container, comprising:
[0121] causing a fog comprising droplets of a mixture to enter the container through one or more openings in the container, the mixture comprising a coating agent in a solvent; wherein
[0122] the fog disperses through the interior of the container to contact the surface of the plurality of items so that a portion of the mixture accumulates on at least a portion of the surfaces of the plurality of items, thereby causing a protective coating to be formed from the coating agent on at least a portion of the surfaces of the plurality of items.
12. The method of embodiment 11, wherein the items are perishable.
13. The method of embodiment 11, wherein the items comprise produce.
14. The method of embodiment 11, wherein the items are maintained within the fog for less than 2 minutes.
15. The method of embodiment 11, wherein causing the protective coating to be formed from the coating agent on at least a portion of the surfaces of the plurality of items comprises at least partially removing the solvent from the mixture on the surfaces of the plurality of items.
16. The method of embodiment 11, wherein causing the protective coating to be formed from the coating agent on at least a portion of the surfaces of the plurality of items comprises cooling or drying the plurality of items via convection through at least one of the openings in the container.
17. A method of forming a protective coating on the surfaces of a plurality of items, comprising:
[0123] forming a fog in an enclosure, the fog comprising droplets of a mixture, the mixture comprising a coating agent in a solvent;
[0124] after at least partially forming the fog, moving the plurality of items into the enclosure, thereby causing the fog to contact at least a portion of the surface of the plurality of items so that a portion of the mixture accumulates on at least a portion of the surfaces of the plurality of items; and
[0125] causing the solvent to be at least partially removed from the mixture on the surface of the plurality of items, thereby forming the protective coating from the coating agent on at least a portion of the surface of the plurality of items.
18. The method of embodiment 17, wherein the items are perishable.
19. The method of embodiment 17, wherein the items comprise produce.
20. The method of embodiment 17, wherein the items are maintained within the fog for less than 2 minutes.
21. A method of forming a protective coating on the surface of pre-harvested produce, comprising:
[0126] forming a fog comprising droplets of a mixture, the mixture comprising a coating agent in a solvent; and
[0127] causing the fog to contact at least a portion of the outer surface of the pre-harvested produce so that a portion of the mixture accumulates on at least a portion of the outer surface of the pre-harvested produce, thereby causing a protective coating to be formed from the coating agent on at least a portion of the outer surface of the pre-harvested produce; wherein
[0128] the fog disperses through openings around the pre-harvested produce to improve coverage of the protective coating on the outer surfaces of the pre-harvested produce.
22. The method of embodiment 21, wherein the pre-harvested produce is maintained within the fog for less than 2 minutes.
23. The method of embodiment 21, wherein causing the protective coating to be formed comprises at least partially removing the solvent from the mixture on at least a portion of the outer surface of the pre-harvested produce.
24. The method of any of embodiments 1-23, wherein the fog is formed by a method comprising:
[0129] (i) heating the mixture to form a vapor; and
[0130] (ii) cooling the vapor to form the fog comprising droplets of the mixture.
25. The method of embodiment 24, wherein the droplets of the fog have an average diameter of about 100 microns or smaller.
26. The method of embodiment 24, wherein heating the mixture comprises passing the mixture through a heat exchanger that is held at a temperature of at least 150 C.
27. A method of forming a protective coating on a surface of a substrate, comprising: heating a mixture to form a vapor, wherein the mixture comprises a coating agent in a solvent;
[0131] cooling the vapor to form a fog comprising droplets of the mixture; and
[0132] causing the fog to contact the surface of the substrate so that a portion of the mixture accumulates on at least a portion of the surface of the substrate, thereby causing a protective coating to be formed from the coating agent on at least a part of the surface of the substrate.
28. The method of embodiment 27, wherein the substrate is maintained within the fog for less than 2 minutes.
29. The method of embodiment 27, wherein causing the protective coating to be formed comprises at least partially removing the solvent from the mixture on the surface of the substrate.
30. The method of any of embodiments 1-23 or 27-29, wherein the droplets have an average diameter of about 100 microns or smaller.
31. The method of any of embodiments 1-10, 15, 17-19, 23, or 29, wherein the at least partially removing the solvent comprises allowing the solvent to evaporate.
32. The method of embodiment 31, wherein at least 95% of the solvent evaporates after 30 minutes or less.
33. The method of any of embodiments 1-23 or 27-29, wherein the protective coating is at least 0.1 microns thick.
34. The method of any of embodiments 1-23 or 27-29, wherein the protective coating is edible.
35. The method of any of embodiments 1-23 or 27-29, wherein the solvent comprises water or ethanol.
36. The method of any of embodiments 1-23 or 27-29, wherein the coating agent comprises monomers, oligomers, fatty acids, esters, amides, amines, thiols, carboxylic acids, ethers, aliphatic waxes, alcohols, or salts.
37. The method of any of embodiments 1-23 or 27-29, wherein the coating agent comprises a compound of Formula I, wherein Formula I is:
##STR00026##
[0133] wherein:
[0134] R is selected from H, -glyceryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, heteroaryl, or a cationic moiety, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more groups selected from halogen (e.g., Cl, Br, or I), hydroxyl, nitro, CN, NH.sub.2, SH, SR.sup.15, OR.sup.14, NR.sup.14R.sup.15, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl;
[0135] R.sup.1, R.sup.2, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are each independently, at each occurrence, H, (CO)R.sup.14, (CO)H, (CO)OH, (CO)OR.sup.14, (CO)O(CO)R.sup.14, O(CO)R.sup.14, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen;
[0136] R.sup.3, R.sup.4, R.sup.7, and R.sup.8 are each independently, at each occurrence, H, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; or
[0137] R.sup.3 and R.sup.4 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or
[0138] R.sup.7 and R.sup.8 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle;
[0139] R.sup.14 and R.sup.15 are each independently, at each occurrence, H, aryl, heteroaryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl;
[0140] the symbol represents a single bond or a cis or trans double bond;
[0141] n is 0, 1, 2, 3, 4, 5, 6, 7 or 8;
[0142] m is 0, 1, 2 or 3;
[0143] q is 0, 1, 2, 3, 4 or 5; and
[0144] r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
38. An assembly for applying a protective coating on a substrate, comprising:
[0145] a reservoir having a mixture therein, the mixture comprising a coating agent in a solvent;
[0146] a heat exchanger; and
[0147] a pump configured to force the mixture through the heat exchanger; wherein
[0148] the heat exchanger is capable of being heated to a sufficiently high temperature to cause the mixture to become a vapor as it is forced through the heat exchanger.
39. The assembly of embodiment 38, further comprising a nozzle, wherein the assembly is configured such that the vapor becomes a fog as it exits the nozzle, and wherein droplets of the fog comprise the mixture.
40. The assembly of any of embodiments 38-39, wherein the coating agent comprises monomers, oligomers, fatty acids, esters, amides, amines, thiols, carboxylic acids, ethers, aliphatic waxes, alcohols, or salts.
41. The assembly of embodiment 40, wherein the solvent comprises water, ethanol, or a combination thereof.
42. The assembly of any of embodiments 38-39, wherein the coating agent comprises a compound of Formula I, wherein Formula I is:
##STR00027##
[0149] wherein:
[0150] R is selected from H, -glyceryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, heteroaryl, or a cationic moiety, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl or heteroaryl is optionally substituted with one or more groups selected from halogen (e.g., Cl, Br, or I), hydroxyl, nitro, CN, NH.sub.2, SH, SR.sup.15, OR.sup.14, NR.sup.14R.sup.15, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl;
[0151] R.sup.1, R.sup.2, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are each independently, at each occurrence, H, (CO)R.sup.14, (CO)H, (CO)OH, (CO)OR.sup.14, (CO)O(CO)R.sup.14, O(CO)R.sup.14, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen;
[0152] R.sup.3, R.sup.4, R.sup.7, and R.sup.8 are each independently, at each occurrence, H, OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, halogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.3-C.sub.7 cycloalkyl, aryl, or heteroaryl wherein each alkyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted with one or more OR.sup.14, NR.sup.14R.sup.15, SR.sup.14, or halogen; or
[0153] R.sup.3 and R.sup.4 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle; and/or
[0154] R.sup.7 and R.sup.8 can combine with the carbon atoms to which they are attached to form a C.sub.3-C.sub.6 cycloalkyl, a C.sub.4-C.sub.6 cycloalkenyl, or 3- to 6-membered ring heterocycle;
[0155] R.sup.14 and R.sup.15 are each independently, at each occurrence, H, aryl, heteroaryl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl;
[0156] the symbol represents a single bond or a cis or trans double bond;
[0157] n is 0, 1, 2, 3, 4, 5, 6, 7 or 8;
[0158] m is 0, 1, 2 or 3;
[0159] q is 0, 1, 2, 3, 4 or 5; and
[0160] r is 0, 1, 2, 3, 4, 5, 6, 7 or 8.
43. The assembly of embodiment 42, wherein the solvent comprises water, ethanol, or a combination thereof.
EXAMPLES
[0161] The following examples compare mass loss rates of coated and uncoated strawberries using the processes disclosed herein. These examples are only for illustrative purposes and are not meant to limit the scope of the present disclosure. In each of the examples, the coatings were formed by fogging the strawberries with a mixture and then allowing the solvent from the mixture to evaporate under ambient conditions. The mixture for each coating was prepared by adding 50 mg/mL of a coating agent to water to form a suspension, where the coating agent includes SA-1G and SA-Na mixed at a 94:6 mass ratio. A Burgess Professional 982 Thermo-Fogger (Fogger 602 pictured in
Example 1: Mass Loss Rate of Strawberries Coated by Fogging and Stored in Ambient Conditions
[0162] 12 conventional strawberry clamshells (storage containers), each having a volume of about 3 L, were filled with strawberries (approximately 55 strawberries per clamshell). The strawberry filled clamshells were split into 4 groups of 3 clamshells per group. The clamshells of the first group were untreated (control group). The clamshells of the second group were each sequentially treated as follows. The clamshell was placed in the 68 L container 604 shown in
[0163] The four groups of strawberries were then kept in their respective clamshells and stored in ambient conditions, and average mass loss rates of each of the groups of strawberries were measured by weighing the strawberry filled clamshells at various time intervals. The average mass loss rates of each of the groups of strawberries are shown in
Example 2: Mass Loss Rate of Strawberries Coated by Fogging and Stored in Cold Storage Conditions
[0164] 12 conventional strawberry clamshells (storage containers), each having a volume of about 3 L, were filled with strawberries (approximately 55 strawberries per clamshell). The strawberry filled clamshells were split into 4 groups of 3 clamshells per group. The clamshells of the first group were untreated (control group). The clamshells of the second group were each treated with 2 layers of fog using the same procedures as those corresponding to the third group (bar 806) in the previous example, except that the fogging time for each layer was 20 seconds. The clamshells of the third group were treated with 2 layers of fog using the same procedures as those corresponding to the second group, except that the fogging time for each layer was 45 seconds. The clamshells of the fourth group were treated with 2 layers of fog using the same procedures as those corresponding to the second and third groups, except that the fogging time for each layer was 90 seconds.
[0165] The four groups of strawberries were then kept in their respective clamshells and stored in cold storage conditions at a temperature of 4 C. and 90% relative humidity, and average mass loss rates of each of the groups of strawberries were measured by weighing the strawberry filled clamshells at various time intervals. The average mass loss rates of each of the groups of strawberries are shown in
[0166] Various implementations of fogging systems and associated methods of use have been described. However, it should be understood that they have been presented by way of example only, and that various changes in form and details may be made. For example, fogging systems described herein can also be used to treat (e.g., coat) other types of substrates, such as meat, poultry, plants, textiles/clothing material, pharmaceuticals, medical equipment, or other substrates, including edible and non-edible substrates. Where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art having the benefit of this disclosure would recognize that the ordering of certain steps may be modified and such modification are in accordance with the variations of the disclosure. Accordingly, other implementations are within the scope of the following claims.