Food with a coating, coating composition, method for manufacturing food with a coating, method for forming a coating, and method for shipping food.

Abstract

The objective is to propose a coated food product, a coating composition, a method for manufacturing the coated food product, a method for forming the coating, and a method for shipping the food product, all of which can maintain the freshness of the food product without using resin packaging film. [Solution] The present invention proposes a coated food having a coating containing a sugar-based surfactant, a coating composition containing a sugar-based surfactant and an aqueous solvent, and a method for manufacturing a coated food and a method for forming a coating by applying the coating composition to the food. The present invention also proposes a method for shipping food, comprising the steps of (A) transporting food, (B) forming a coating on food, and (C) inspecting the coated food using an evaluation device, wherein in step (B), the coating is formed by the coating forming method.

Description

Technical Field

[0001] The present invention relates to a coated food, a coating composition, a method for producing a coated food, a film-forming method, and a method for shipping food.

Background Art

[0002] In recent years, packaging materials that can maintain the freshness of food during distribution or storage, such as those represented by MA (Modified Atmosphere) packaging, have attracted attention. From the perspective of reducing environmental impact, there is a tendency towards so-called monomaterialization, which is composed of a single material so that the packaging materials used can be recycled or easily discarded after use. Therefore, a technique has been proposed in which a quality-retaining agent is directly applied to foods such as fruits and vegetables to maintain the freshness of the foods (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the above methods have a short freshness retention period, the materials used are compositions that are not friendly to the human body, and they are not always sufficient in terms of expressing freshness retention performance. Therefore, an object of the present invention is to propose a coated food, a coating composition, a method for producing a coated food, a film-forming method, and a method for shipping food that can maintain the freshness of food.

Means for Solving the Problems

[0005] The inventors considered that evaporation from food during distribution or storage is one of the factors contributing to the deterioration of freshness, and investigated various coatings with high water vapor barrier properties. They found that the above problem can be solved by applying a coating containing a specific surfactant to food.

[0006] In other words, the present invention has the following aspects. [1] A coated food having a coating containing a sugar-based surfactant. [2] The coated food according to [1], wherein the sugar-based surfactant is a sucrose fatty acid ester. [3] The coated food according to [1] or [2], wherein the lipophilic group of the sugar-based surfactant is a saturated fatty acid. [4] A coated food according to any one of [1] to [3], comprising 50% by mass or more of a sugar fatty acid ester having 3 or fewer fatty acid ester groups, when the total amount of the sugar-based surfactant is 100% by mass. [5] The coated food according to any one of [1] to [4], wherein the HLB of the sugar-based surfactant is 5 or more. [6] A coated food according to any one of [1] to [5], wherein the average thickness of the coating is 0.1 μm or more and 10 μm or less. [7] A coated food according to any one of [1] to [6], wherein the crystal melting peak temperature of the coating is 40°C or higher and 80°C or lower. [8] The coated food according to any one of [1] to [7], wherein the food is a fresh vegetable. [9] The coated food according to any one of [1] to [8], wherein the coating covers only a portion of the food.

[10] A coating composition comprising a sugar-based surfactant and an aqueous solvent.

[11] The coating composition according to

[10] , wherein the sugar-based surfactant is a sucrose fatty acid ester.

[12] The coating composition according to

[10] or

[11] , wherein the lipophilic group of the sugar-based surfactant is a saturated fatty acid.

[13] A coating composition according to any one of

[10] to

[12] , comprising 50% by mass or more of a sugar fatty acid ester having 3 or fewer fatty acid ester groups, when the total amount of the sugar-based surfactant is 100% by mass.

[14] The coating composition according to any one of

[10] to

[13] , wherein the HLB of the sugar-based surfactant is 5 or more.

[15] The coating composition according to any one of

[10] to

[14] , wherein the content of the sugar-based surfactant among the nonvolatile components in the coating composition is 60% by mass or more.

[16] The coating composition according to any one of

[10] to

[15] , wherein the aqueous solvent is water or alcohol. A film comprising any one of the coating compositions described in

[17] ,

[10] , to

[16] . A method for producing coated food, comprising the steps of applying a coating composition described in any one of

[18]

[10] to

[16] to food, or applying a sugar-based surfactant to food without a solvent.

[19] The method for producing a coated food according to

[18] , wherein the coating method is immersion or spraying.

[20] A method for producing a coated food according to

[18] or

[19] , wherein the coating composition or the sugar-based surfactant is applied to a part of the food.

[21] A method for producing a coated food according to

[18] or

[19] , wherein the coating composition or sugar-based surfactant is applied to the food, and a portion of the applied coating composition or sugar-based surfactant is removed. A method for forming a film, comprising the steps of applying a coating composition described in any one of

[22]

[10] to

[16] to food, or applying a sugar-based surfactant to food without a solvent.

[23] The method for forming a coating according to

[22] , wherein the coating method is an immersion method or a spray method.

[24] The method for forming a film according to

[22] or

[23] , wherein the coating composition or the sugar-based surfactant is applied to a part of the food.

[25] After applying the coating composition or the sugar-based surfactant to food, a part of the applied coating composition or sugar-based surfactant is removed, the film-forming method according to

[22] or

[23] .

[26] A method for shipping food, including the steps of (A) transporting food, (B) forming a film on the food, and (C) inspecting the food with a film using an evaluation device. In the step (B), a film is formed by the method according to any one of

[22] to

[25] .

[27] The food shipping method according to

[26] , wherein the step (C) inspection includes at least one inspection selected from the group consisting of appearance inspection, sugar content inspection, and size inspection. [Effect of the Invention]

[0007] The food with a film of the present invention has a film with high water vapor barrier properties, so that transpiration from the food can be suppressed, and freshness can be maintained over a long period. Since the film also has oxygen barrier properties, especially in the case of fresh fruits and vegetables, aging due to respiration can also be suppressed. <00…​​​​​​​​​​​​​​​​​​​​​​Note that the film does not necessarily have to cover the entire food, and it may cover only a part of the food as long as it can suppress transpiration and respiration from the food. For example, when the food is a fresh fruit or vegetable, the film may cover only a part of the fresh fruit or vegetable. The area of the film is preferably 10% or more, more preferably 25% or more, still more preferably 40% or more, and even more preferably 50% or more with respect to the surface area of the whole fresh fruit or vegetable. Further, from the viewpoint of maintaining the freshness of fresh fruits and vegetables, it is preferable that the film covers at least the part where transpiration of moisture is high. Examples of the part where transpiration of moisture is high include the stomata on the back of leaves, stems, pedicels, rachis, calyx or roots, or the cut surface at the time of harvesting. Furthermore, from the viewpoint of maintaining the freshness without significantly changing the appearance of fresh fruits and vegetables, it is preferable to cover only the part where transpiration of moisture is high.

[0011] [Food] Examples of the food in the present invention include fresh foods such as fresh fruits and vegetables, meat, and fish, and processed foods such as dairy products and bakery products. Among them, since the film of the present invention is excellent in water vapor barrier properties, it is preferably applied to fresh fruits and vegetables or dairy products whose quality is likely to deteriorate due to transpiration. Further, since the film also has oxygen barrier properties, it is more preferably applied to fresh fruits and vegetables that undergo aging due to respiration. As for fresh produce, for example, apples, cherries, peaches, green plums, oranges, grapefruits, mandarins, sudachi and other citrus fruits, persimmons, figs, strawberries, kiwifruit, grapes, blueberries, bananas, mangoes, melons, papayas, lychees, apricots, avocados, cantaloupes, guavas, nectarines, pears (Japanese pears, European pears, etc.), plums, etc.; radishes, carrots, burdock Examples include: root vegetables such as bamboo shoots, sweet potatoes, onions, ginger, taro, and yams; leafy and stem vegetables such as asparagus, cabbage, lettuce, spinach, Chinese cabbage, cauliflower, and broccoli; fruit vegetables such as tomatoes, eggplants, pumpkins, bell peppers, and cucumbers; wild vegetables such as bracken and fiddlehead ferns; mushrooms such as shiitake, king oyster mushrooms, buna shimeji, hon shimeji, enoki mushrooms, and maitake mushrooms; and cut flowers such as chrysanthemums, roses, and lilies. Examples of dairy products include cheese and butter.

[0012] [Sugar-based surfactants] Sugar-based surfactants are nonionic surfactants that use sugar as a hydrophilic group.

[0013] The HLB of the sugar-based surfactant of the present invention is not particularly limited, but from the viewpoint of being able to dissolve in an aqueous solvent and form a film, it is preferably 5 or higher, more preferably 7 or higher, and even more preferably 9 or higher. The upper limit of HLB is usually 20, and 18 or lower is more preferable.

[0014] The sugar-based surfactant of the present invention is preferably crystalline in order to suppress the stickiness of the resulting film and to enhance its water vapor barrier and oxygen barrier properties. The presence or absence of crystallinity of the sugar-based surfactant in the film can be confirmed by the presence or absence of a crystal melting peak temperature measured on the film. Therefore, it is preferable that a crystal melting peak originating from the sugar-based surfactant is detected in the DSC described later. The crystal melting peak temperature of the coating is preferably 40°C to 80°C, and more preferably 45°C to 70°C. A crystal melting peak temperature of 40°C or higher helps to suppress the stickiness of the resulting coating. On the other hand, a crystal melting peak temperature of 80°C or lower allows for less heating when dissolving in an aqueous solvent, resulting in good productivity. The crystal melting peak temperature is the temperature at which the crystal melting peak is detected in differential scanning calorimetry (DSC) measured at a heating rate of 10°C / min.

[0015] From the viewpoint of suppressing the stickiness of the resulting film, the sugar-based surfactant of the present invention preferably contains 60% by mass or more of a component that becomes solid at room temperature (20-25°C), more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more. The sugar-based surfactant may consist only of a component that becomes solid at room temperature (20-25°C), and therefore, the above ratio may be 100% by mass or less.

[0016] Examples of sugar-based surfactants of the present invention include sugar fatty acid esters formed by ester bonding of sugar and fatty acid, and alkyl glycosides formed by glycosidic bonding of sugar and higher alcohol, with sugar fatty acid esters being preferred among them. The lipophilic group of a sugar-based surfactant is preferably a saturated fatty acid. Therefore, in sugar fatty acid esters, it is preferable that the constituent fatty acids of the sugar fatty acid ester include saturated fatty acids, as will be described later. Details of saturated fatty acids will be described later.

[0017] (Sugar fatty acid esters) The sugar fatty acid ester is not particularly limited as long as it is suitable for use in food, but examples include sucrose fatty acid ester, sorbitan fatty acid ester, glucose ester, etc., with sucrose fatty acid ester being preferred. Sucrose fatty acid ester can take on a crystalline structure, which results in higher water vapor barrier and oxygen barrier properties of the resulting coating. Furthermore, it is not necessary to use only one type of sugar-based surfactant; two or more types may be used in combination. When two or more types are combined, it is preferable that 60% or more by mass of the total sugar-based surfactant is sucrose fatty acid ester, when the total amount of sugar-based surfactant is considered as 100% by mass. From the viewpoint of suppressing the stickiness of the resulting film and improving the water vapor barrier and oxygen barrier properties, this ratio is more preferably 70% or more by mass, even more preferably 80% or more by mass, and even more preferably 90% or more by mass. The sugar-based surfactant may also be sucrose fatty acid ester alone; therefore, the above ratio may be 100% or less by mass.

[0018] The constituent fatty acids of the sugar fatty acid ester are preferably edible oils and fats. The number of carbon atoms in the constituent fatty acids of the sugar fatty acid ester is not particularly limited, but is preferably between 12 and 22, more preferably between 12 and 18, and even more preferably between 14 and 18. Having the carbon number within this range helps to suppress the stickiness of the resulting coating. Furthermore, the constituent fatty acids of the sugar fatty acid ester may be saturated or unsaturated fatty acids, but saturated fatty acids are preferred because they tend to solidify at room temperature (20-25°C) and can suppress the stickiness of the resulting film. More specifically, examples include lauric acid, myristic acid, pentadecyl acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, and oleic acid. Among these, lauric acid, myristic acid, palmitic acid, and stearic acid, which are saturated fatty acids with 12 to 18 carbon atoms, are preferred, and myristic acid, palmitic acid, and stearic acid, which are saturated fatty acids with 14 to 18 carbon atoms, are more preferred. These saturated fatty acids may be used individually or in combination of two or more. Furthermore, the constituent fatty acids of the sugar fatty acid ester do not all need to be the same; it is sufficient if 60% or more by mass of the constituent fatty acids in the sugar fatty acid ester are the preferred constituent fatty acids mentioned above. From the viewpoint of suppressing the stickiness of the resulting film, this ratio is preferably 70% or more by mass, more preferably 80% or more by mass, and even more preferably 90% or more by mass. There is no particular upper limit, but it should be 100% or less by mass. The constituent fatty acid composition of sugar fatty acid esters can be determined by isolating the sugar fatty acid esters from the composition, derivatizing them, and then measuring them by gas chromatography.

[0019] The number of fatty acid ester groups in sugar fatty acid esters varies depending on the number of ester-bondable hydroxyl groups in the molecular structure of the hydrophilic sugar. For example, sucrose fatty acid esters have 1 to 8 ester groups, while sorbitan fatty acid esters have 2 to 4. In the present invention, from the viewpoint of being able to form a film when dissolved in an aqueous solvent, it is preferable that the total amount of sugar-based surfactants be 100% by mass, and that the mixture contains 50% by mass or more of sugar fatty acid esters (monoesters, diesters, or triesters) having 3 or fewer fatty acid ester groups, more preferably 60% by mass or more, and even more preferably 70% by mass or more. There is no particular upper limit, but it is sufficient if it is 100% by mass or less. Furthermore, from a similar viewpoint, when the total amount of sugar-based surfactants is taken as 100% by mass, it is preferable that the product contains 30% by mass or less of sugar fatty acid esters (hexaesters, heptaesters, octaesters, or more) having 6 or more fatty acid ester groups, more preferably 20% by mass or less, and even more preferably 10% by mass or less. Sugar fatty acid esters having 6 or more fatty acid ester groups do not need to be included, and their content should be 0% by mass or less.

[0020] The content ratio for each number of fatty acid ester groups can be measured after isolating the sugar fatty acid esters from the composition, according to the METHOD OF ASSAY described in the Residue Monograph prepared by the meeting of the Joint FAO / WHO Expert Committee on Food Additives (JECFA), 84th meeting 2017 “Sucrose Esters of Fatty Acids” and Prepared at the 71st JECFA (2009) and published in FAO JECFA Monographs 7 (2009) “Sucrose Oligoesters Type I” and “Sucrose Oligoesters Type II”.

[0021] Measurement of monoesters, triesters, and tetraesters and above After dissolving the sample in a fixed amount of tetrahydrofuran (GPC containing stabilizers or industrial grade), insoluble matter is removed using a 0.5 μm membrane filter to obtain the solution, which is then used as the measurement sample. High-performance liquid chromatography is performed under the following conditions. The composition ratio is calculated by individually determining the peak area for each monoester to triester and the combined peak area for tetraesters and above, and then calculating the ratio to the total peak area of ​​all peaks detected up to 43 minutes. The peak area corresponds to the area from the starting point (rising point) to the ending point (falling point) of each peak. If two or more peaks are adjacent and the start and end points are unknown, the point where the data between the peaks is minimized is used as the start and end point, and the area is calculated accordingly.

[0022] <Measurement conditions: Monoesters to triesters and tetraesters and above> Equipment: HLC-8320GPC; Detector: Differential refractometer (manufactured by Tosoh Corporation) Columns: TSK-Gel G1000HXL, G2000HXL, G3000HXL, G4000HXL (manufactured by Tosoh Corporation) Column temperature: 40℃ Detector temperature: 40℃ Eluent: Tetrahydrofuran (GPC containing stabilizer or industrial grade) Flow rate: 0.8ml / min Injection volume: 80μl Measurement time: 50 minutes (Area ratio is calculated based on all peaks detected up to 43 minutes)

[0023] Measurement of tetraesters and octaesters After dissolving the sample in a fixed amount of methanol (reagent grade) / tetrahydrofuran (HPLC grade without stabilizers) = 20 / 80 (vol / vol), insoluble matter is removed using a 0.45 μm membrane filter. The resulting solution is used as the measurement sample, and high-performance liquid chromatography is performed under the following conditions. The composition ratio of tetraesters to octaesters is calculated by individually determining the peak area of ​​each tetraester to octaester, calculating the ratio to the total peak area of ​​tetraesters to octaesters, and then apportioning the area ratio of tetraesters and above, obtained in the above section "Measurement of monoesters to triesters and tetraesters and above," according to the area ratio of tetraesters to octaesters. The peak area corresponds to the area from the starting point (rising point) to the ending point (falling point) of each peak. If two or more peaks are adjacent and the start and end points are unknown, the point where the data between the peaks is minimized is used as the start and end point, and the area is calculated accordingly.

[0024] <Measurement conditions: Tetraester to octaester> Device Degasser: DGU-20A (manufactured by Shimadzu Corporation) Pump: LC-20AD (manufactured by Shimadzu Corporation) Oven: CTO-20A (manufactured by Shimadzu Corporation) Detector: RID-20A Differential Refractometer (manufactured by Shimadzu Corporation) Column: 150mm x 4.6mm ID; ODS-2 (manufactured by GL Science Co., Ltd.) Column temperature: 40℃ Detector temperature: 40℃ Eluent: Methanol (reagent grade) / Tetrahydrofuran (HPLC grade, stabilizer-free) = 70 / 30~50 / 50 (vol / vol) Flow rate: 0.8ml / min Injection volume: 20μl Measurement time: 16 minutes

[0025] [Physical properties of the coating] (Average film thickness) The average film thickness of the coating of the present invention is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 5 μm or less. An average film thickness of 0.1 μm or more provides good water vapor barrier and oxygen barrier properties. On the other hand, an average film thickness of 10 μm or less allows for the formation of a coating while maintaining the texture of the food. In this invention, the thickness of the coating does not need to be uniform throughout the entire food product. The average thickness of the coating can be determined by freeze-drying the coated food beforehand, peeling off the coating, observing the cross-section with an electron microscope or metallurgical microscope, and measuring the thickness at 10 or more randomly selected points, then calculating the average value.

[0026] (Water vapor barrier properties) The coating of the present invention has a water vapor transmission rate of 0.1 to 20 g / m² per 1 μm at 30°C and 50% RH. 2 It is preferable that the amount is 0.5-10 g / (m 2 • day) is more preferable, 1-5 g / (m 2 A day is even more preferable. When the water vapor transmission rate is within the above range, evaporation from the food can be suppressed, and freshness can be maintained. Furthermore, the water vapor transmission rate (WVTR) can be measured using the differential pressure method with the DELTAPERM water vapor transmission rate measuring device, in accordance with JIS K7129-5. More specifically, it is the value obtained by converting the measured water vapor transmission rate when coated on a polyethylene terephthalate film with a thickness of 50 μm under conditions of 30°C and 50% RH to a transmission rate per μm using the following formula.

[0027]

number

[0028] (Oxygen barrier properties) The coating of the present invention has an oxygen permeability of 0.1 to 100 cc / (m²) per 1 μm at 25°C and 50% RH. 2 It is preferable that the pressure is 0.5-90cc / (m³). 2 (day / atm) is more preferable, 1-50cc / (m 2 A temperature of (day·atm) is even more preferable. When the oxygen permeability is within the above range, aging due to respiration of fruits and vegetables can be suppressed, and freshness can be maintained more effectively. The oxygen permeability (OTR) can be measured using the isobaric method with the OX-TRAN 2 / 21 oxygen permeability measuring device (manufactured by MOCON Corporation) in accordance with JIS K7126-2. More specifically, it is the value obtained by converting the measured oxygen permeability when coated on a 50 μm thick polyethylene terephthalate film under conditions of 25°C and 50% RH to the permeability per μm using the following formula.

[0029]

number

[0030] <Coating composition> The coating composition of the present invention contains a sugar-based surfactant and an aqueous solvent. Because the film obtained from this coating composition exhibits excellent water vapor barrier properties, it is suitable for food applications. Furthermore, because the film also possesses oxygen barrier properties, it is particularly suitable for use with fresh produce. It is preferable that the aqueous solvent be removed from the film obtained from the coating composition, as described later.

[0031] [Sugar-based surfactants] As for sugar-based surfactants, those described in the section above on "Foods with Film Coating" can be used.

[0032] [Water-based solvents] Examples of aqueous solvents in the present invention include water and alcohols such as ethanol, isopropanol, ethylene glycol, and glycerin. From the viewpoint of being applicable to food, an aqueous coating composition using water as the solvent is preferred, but from the viewpoint of stability and applicability, a small amount of organic solvent such as the above-mentioned alcohols may be included in addition to water as the solvent. The content of the organic solvent in the coating composition is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0033] [pH adjuster] The coating composition of the present invention may contain a pH adjuster. Examples of pH adjusters that can be used include acetic acid, lactic acid, citric acid, and ammonia.

[0034] [Physical properties of the coating composition] (Concentration of non-volatile components) The concentration of nonvolatile components in the coating composition is not particularly limited, but is preferably 0.1% by mass or more and 60% by mass or less, more preferably 0.2% by mass or more and 50% by mass or less, even more preferably 0.3% by mass or more and 40% by mass or less, even more preferably 0.5% by mass or more and 20% by mass or less, and particularly preferably 1% by mass or more and 10% by mass or less. By setting the concentration of nonvolatile components to 0.1% by mass or more and 60% by mass or less, it becomes easier to form a coating with a suitable film thickness while appropriately dissolving the sugar-based surfactant in an aqueous solvent. In this invention, "non-volatile component concentration" refers to the concentration of non-volatile components excluding the solvent contained in the coating composition.

[0035] (Content of sugar-based surfactants) From the viewpoint of enhancing the water vapor barrier and oxygen barrier properties of the resulting coating film, the sugar-based surfactant content is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more, with a maximum of 100% by mass, of the non-volatile components in the coating composition. Since the coating in the present invention is obtained by volatilizing the solvent from the coating composition, the preferred content of the sugar-based surfactant in the coating is the same as described above.

[0036] (pH of the coating composition) From the viewpoint of safe application to food, the pH of the coating composition is preferably between 4 and 10, and more preferably between 4 and 8.

[0037] <Method for manufacturing coated foods> The coated food product of the present invention is manufactured by applying the above-mentioned coating composition to the food product, or by applying the above-mentioned sugar-based surfactant to the food product without a solvent. After applying the above-mentioned coating composition to the food product, drying may be performed. For the application and drying of the coating composition and the solvent-free application of the sugar-based surfactant, the method described in the "film-forming method" described later can be suitably used.

[0038] <Film formation method> The film-forming method of the present invention (hereinafter also referred to as "this method") includes a method of applying the above-mentioned coating composition to food, or a method of applying the above-mentioned sugar-based surfactant to food without a solvent.

[0039] [Application of coating composition] When applying a coating composition to food, the application method is not particularly limited. Examples include brush application, direct application of the coating liquid to the food (such as curtain coating), immersion methods (such as impregnation coating), and spraying methods (such as spray coating). Of these methods, the immersion method or the spray method is preferred from the viewpoint of being able to coat the surface of food with a three-dimensional shape relatively uniformly. Furthermore, if the food product is fresh produce, depending on the type of produce and the ease of application, the coating may be formed on the surface of the produce after harvest, or the coating may be formed on the surface of the produce before harvesting. If the coating is formed before harvesting, it is desirable to form the coating when the produce has reached the desired level of maturity.

[0040] In this method, from the viewpoint of shortening the drying time of the coating composition and improving the efficiency of the film formation process, it is preferable to apply the coating composition to a part of the food. For example, if the food is a fruit or vegetable, the coating composition may be applied to only a portion of the fruit or vegetable. In this case, the coating area is preferably 10% or more of the total surface area of ​​the fruit or vegetable, more preferably 25% or more, even more preferably 40% or more, and even more preferably 50% or more. Furthermore, from the viewpoint of maintaining the freshness of fruits and vegetables, it is preferable to apply the coating composition to at least the parts where moisture evaporation is high. From the perspective of minimizing the amount of sugar-based surfactants used, the coating composition may be applied only to areas where there is a high rate of moisture evaporation.

[0041] In this method, after applying the coating composition to the food, a portion of the applied coating composition may be removed. The removal method is not particularly limited, but examples include removal by air pressure using an air dryer. For example, removing excess coating composition from the food surface can prevent poor drying of areas where an excessive amount has been applied. Furthermore, by removing the coating composition from a portion of the food, the amount of sugar-based surfactants used can be minimized. If the food is a fresh vegetable, freshness can be maintained by covering at least the parts where moisture evaporates easily, so the coating composition on other parts may be removed. Regarding the application method, an example can be found in "Coating Method," written by Yuji Harasaki and published by Maki Shoten in 1979.

[0042] [Drying] After applying the coating composition to food, the film may be dried for purposes such as removing the aqueous solvent. Examples of drying methods include static drying, air drying, or heat drying, but from the viewpoint of preserving the freshness of the food, a method of drying by static drying at room temperature (20-25°C) or air drying at room temperature is preferred.

[0043] [Solvent-free coating of sugar-based surfactants] When applying sugar-based surfactants to food without a solvent, it is preferable to heat the sugar-based surfactant to a temperature at which it exhibits fluidity (for example, from the melting point of the sugar-based surfactant to the melting point + 30°C) and then apply it to the food using a curtain coat or spray coat. When applying without a solvent, a product consisting solely of sugar-based surfactants may be applied to the food, but sugar-based surfactants may also be mixed with other components (such as non-volatile components) as appropriate.

[0044] Similar to the above [application of coating composition], from the viewpoint of improving the efficiency of the film formation treatment, it is preferable to apply the sugar-based surfactant to a part of the food. Alternatively, after applying the sugar-based surfactant to the food, a portion of the applied sugar-based surfactant may be removed.

[0045] <Food shipping methods> The present invention relates to a method for shipping food products, comprising the steps of (A) transporting food products, (B) forming a coating on the food products, and (C) inspecting the coated food products using an evaluation device, wherein in step (B), a coating is formed on the food products using the coating forming method of the present invention. The coated and inspected food products are then shipped to the consumer by a transportation company or the like. Note that the order of steps (B) and (C) in the above shipping method may be reversed. That is, the order may be (A), (B), and (C), or (A), (C), and (B). In the following sections, we will explain the process in the order of (A), (B), and (C) as an example, based on the diagram shown in Figure 1.

[0046] Figure 1 is an illustrative diagram of the food shipping method of the present invention. (A) The food transport process is a process for supplying the food to process (B). The method is not particularly limited, and for example, the food may be transported continuously by a belt conveyor or a large amount of food may be transported together by truck or the like. Figure 1 shows a configuration in which food products 10 are transported using a belt conveyor 11. The food products 10 are placed on the belt conveyor and subjected to process (B) by rotating the rotating roll 12.

[0047] The next step (B) is to form a coating on the food 10 that was transported in step (A). The method described in the "Method for Forming a Coating" above can be suitably used to form the coating. Figure 1 illustrates one preferred embodiment: the immersion method. The food 10 is immersed in an immersion tank 13 filled with the coating composition of the present invention, and the coating composition is applied to the surface of the food. The belt conveyor is equipped with food fixing means such as claws, and the food 10 is transported into and out of the immersion tank in a fixed state. After that, the solvent is removed in a drying oven 14, and a coating is formed on the food 10. However, the drying oven 14 may be omitted, and the food 10 may be left to dry at room temperature, or drying may be omitted in the case of solvent-free coating.

[0048] In the case where a coating is to be formed on only a portion of the food in step (B), it is preferable that the coating composition is applied or sprayed onto the food 10 placed on the belt conveyor and then transported to the drying oven 14. Alternatively, a portion of the food 10 may be immersed in the immersion tank 13 by a food gripping means such as a robotic hand, and then placed on a belt conveyor with the immersed surface facing upwards and transported to the drying oven 14.

[0049] After the food 10 has been immersed in the immersion tank 13, a portion of the applied coating composition may be removed by an air dryer (not shown) or the like.

[0050] Next, step (C) is a step in which the food product 10, which has a coating formed in step (B), is inspected using an evaluation device 15. The evaluation device can include an optical sensor, a weighing scale, a camera, etc. (C) Various inspection items can be listed as inspections in the inspection process, but it is preferable to include at least one inspection selected from the group consisting of visual inspection, sugar content inspection, and size inspection. Furthermore, because the coating in this invention has high transparency, it does not interfere with non-destructive testing using light, such as sugar content testing. Therefore, conventional testing methods used for food products (for example, Japanese Patent Application Publication No. 2012-78206) can be used as is.

[0051] As described above, coated food products that have gone through (A) the transport process, (B) the coating process, and (C) the inspection process are shipped by conventional means. Figure 1 shows an example of shipment by shipping vehicle 16. [Examples]

[0052] Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples described below.

[0053] <Example Test 1: Japanese Pear (Kosui)> In Test Example 1, a film was formed on the surface of Japanese pears (Kosui variety) to evaluate their freshness retention.

[0054] [Example 1] As a sugar-based surfactant, "Ryoto® Sugar Ester L-1695" (sucrose laurate ester, HLB: 16, mono-to-tryester content: 96% by mass or more) manufactured by Mitsubishi Chemical Corporation was used, and aqueous coating composition 1-1 was prepared by dissolving it in water so that the sugar-based surfactant content was 5% by mass. The aqueous coating composition 1-1 described above was applied to the surface of a Japanese pear by immersion, and dried at room temperature (20-25°C) for 30 minutes to form a film with a thickness of 1.5 μm.

[0055] [Example 2] As a sugar-based surfactant, "Ryoto® Sugar Ester P-1570" (sucrose palmitate, HLB: 15, mono-tryester content: 96% by mass or more) manufactured by Mitsubishi Chemical Corporation was used, and aqueous coating compositions 1-2 were prepared by dissolving it in water so that the sugar-based surfactant content was 5% by mass. Using the aqueous coating compositions 1-2 described above, a film with a thickness of 1.5 μm was formed in the same manner as in Example 1.

[0056] [Example 3] As a sugar-based surfactant, "Ryoto® Sugar Ester S-570" (sucrose stearate ester, HLB: 5, mono-tryester content: 86% by mass or more) manufactured by Mitsubishi Chemical Corporation was used, and aqueous coating compositions 1-3 were prepared by dissolving it in water so that the sugar-based surfactant content was 5% by mass. Using the aqueous coating compositions 1-3 described above, a film with a thickness of 1.5 μm was formed in the same manner as in Example 1.

[0057] [Example 4] As a sugar-based surfactant, "Ryoto® Sugar Ester S-1670" (sucrose stearate ester, HLB: 16, mono-to-tryester content: 97% by mass or more) manufactured by Mitsubishi Chemical Corporation was used, and aqueous coating compositions 1-4 were prepared by dissolving it in water so that the sugar-based surfactant content was 5% by mass. Using the aqueous coating compositions 1-4 described above, a film with a thickness of 1.5 μm was formed in the same manner as in Example 1.

[0058] [Comparative Example 1] Japanese pears that do not form a coating were used as Comparative Example 1.

[0059] [Freshness Preservation Evaluation] The freshness preservation of the coated Japanese pears from Examples 1-4 and the Japanese pear from Comparative Example 1 was evaluated based on weight retention rate, hardness retention rate, color, and taste. Japanese pears are already quite sweet and ready to eat even when unripe. As they ripen, their color changes from green to brown, and if they ripen too much, they lose their characteristic crisp texture, reducing their market value. For the reasons stated above, in the case of Japanese pears, in addition to weight retention rate to confirm transpiration suppression, the freshness preservation effect was confirmed by hardness retention rate, color, and taste.

[0060] (Weight maintenance rate) For the coated Japanese pears of Examples 1-4 and the Japanese pear of Comparative Example 1, the weight retention rate ((weight after storage / weight on day 0) × 100 (%)) was calculated after storage for 10 and 14 days at 20°C and 90% RH, using the weight of the Japanese pear before storage (day 0) as the baseline.

[0061] (Hardness maintenance rate) The hardness of the cross-section of the Japanese pears at the time of fracture was measured using a fruit hardness meter KM-5 (manufactured by Fujiwara Seisakusho Co., Ltd.) for the coated Japanese pears of Examples 1-4 and the Japanese pear of Comparative Example 1. A cylindrical tip was used for the fruit hardness meter. The hardness of the Japanese pears before storage (day 0) was used as the baseline, and the hardness retention rate ((hardness after 14 days of storage / hardness on day 0) × 100 (%)) after 14 days of storage at 20°C and 90% RH was calculated.

[0062] (color) The base color of the coated Japanese pears from Examples 1-4 and the Japanese pear from Comparative Example 1 was evaluated using a fruit color chart supervised by the Fruit Tree Experiment Station of the Ministry of Agriculture, Forestry and Fisheries. The evaluation was performed twice: before storage (day 0) and after 10 days of storage at 20°C and 90% RH. In this evaluation using the fruit color chart, a higher numerical value indicates further ripening.

[0063] (Taste) Taste tests were conducted on four subjects using the coated Japanese pears from Examples 1-4 and the Japanese pear from Comparative Example 1, and evaluated according to the following criteria. Evaluations were performed twice: before storage (day 0) and after 14 days of storage at 20°C and 90% RH. As mentioned above, the texture of Japanese pears affects their commercial value, so a rating of B or higher was considered a pass, and C was considered a fail. The rating with the highest number of votes from the four subjects is listed in Table 1. If the ratings were split between two subjects, the lower rating is listed in the table. A: The texture is equivalent to that of a blank (the state of Comparative Example 1 on day 0). B: Compared to the blank, it lacks the crisp texture that is characteristic of Japanese pears. C: It has absolutely no crunchy texture.

[0064] Table 1 shows the configurations and evaluation results of Examples 1-4 and Comparative Example 1.

[0065] [Table 1]

[0066] Table 1 shows that the coated Japanese pears of Examples 1-4 were superior to the Japanese pear of Comparative Example 1 in terms of weight retention, hardness retention, color, and taste. Therefore, it was confirmed that applying a coating containing a sugar-based surfactant to the surface of Japanese pears can provide a freshness preservation effect.

[0067] <Test Example 2: Avocado> In Test Example 2, a film was formed on the surface of avocados to evaluate their freshness retention.

[0068] [Example 5] Aqueous coating composition 2-1 was prepared by using "Ryoto® Sugar Ester S-570" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. The aqueous coating composition 2-1 described above was applied to the surface of an avocado by immersion, and dried at room temperature (20-25°C) for 30 minutes to form a film with a thickness of 1.5 μm.

[0069] [Example 6] As a sugar-based surfactant, "Ryoto® Sugar Ester S-970" (sucrose stearate ester, HLB: 9, mono-tryester content: 92% by mass or more) manufactured by Mitsubishi Chemical Corporation was used, and aqueous coating composition 2-2 was prepared by dissolving it in water so that the sugar-based surfactant content was 5% by mass. Using the aqueous coating composition 2-2 described above, a film with a thickness of 1.5 μm was formed in the same manner as in Example 5.

[0070] [Example 7] As a sugar-based surfactant, "Ryoto® Sugar Ester S-1170" (sucrose stearate ester, HLB: 11, mono-to-tryester content: 94% by mass or more) manufactured by Mitsubishi Chemical Corporation was used, and aqueous coating compositions 2-3 were prepared by dissolving it in water so that the sugar-based surfactant content was 5% by mass. Using the aqueous coating compositions 2-3 described above, a film with a thickness of 1.5 μm was formed in the same manner as in Example 5.

[0071] [Example 8] Aqueous coating compositions 2-4 were prepared by using "Ryoto® Sugar Ester S-1670" manufactured by Mitsubishi Chemical Corporation as a sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. Using the aqueous coating compositions 2-4 described above, a film with a thickness of 1.5 μm was formed in the same manner as in Example 5.

[0072] [Comparative Example 2] Avocado that did not form a film was used as Comparative Example 2.

[0073] [Freshness Preservation Evaluation] The freshness preservation of the coated avocados from Examples 5-8 and the avocado from Comparative Example 2 was evaluated based on weight retention, hardness, and color. As avocados ripen, they soften and change color from green to dark purple. These changes are easily noticeable, and consumers generally evaluate the freshness of avocados by their firmness and color. Therefore, for avocados, in addition to weight retention to confirm transpiration suppression, we confirmed the freshness preservation effect by examining firmness and color.

[0074] (Weight maintenance rate) For the coated avocados of Examples 5-8 and the avocado of Comparative Example 2, the weight retention rate ((weight after storage / weight on day 0) × 100 (%)) was calculated after storage at 25°C and 50% RH for 3, 8, 11, and 16 days, using the weight of the avocado before storage (day 0) as the baseline.

[0075] (Hardness) Four avocados were prepared from each of the coated avocados in Examples 5-8 and Comparative Example 2, and their hardness was evaluated when the surface was lightly pressed with a finger. ○ (good): The hardness is equivalent to or slightly softer than the blank (condition of Comparative Example 2 on day 0), and there is little deformation when the surface is pressed. ×(bad): It is considerably softer than the blank, and deforms significantly when the surface is pressed. The above evaluation was performed six times: before storage (day 0) and after storage at 25°C and 50% RH for 3, 8, 11, 16, and 21 days. The change in hardness was evaluated according to the following criteria. A: Over 75% of the samples can be rated as ○ (good). B: More than 50% of the samples could be rated as ○ (good), but less than 75%. C: More than 25% of the samples could be rated as ○ (good), but less than 50%. D: The percentage of samples that can be evaluated as ○ (good) is greater than 0% and less than 25%. E: No samples were found that could be rated as ○ (good) (0%).

[0076] (color) Four avocados were prepared for each of the coated avocados from Examples 5-8 and Comparative Example 2, and the color change was evaluated according to the following criteria. The evaluation was performed five times: before storage (day 0), and after storage at 25°C and 50% RH for 3, 8, 11, and 16 days. The color change was evaluated according to the following criteria. A: There were no samples with a completely blackish-purple surface (0%), or less than 25%. B: Between 25% and 50% of the samples had a completely blackish-purple surface. C: More than 50% but less than 75% of the samples had a completely blackish-purple surface. D: More than 75% but less than 100% of the samples had a completely blackish-purple surface. E: The surface of all samples is completely blackish-purple (100%).

[0077] Table 2 shows the configurations and evaluation results of Examples 5-8 and Comparative Example 2.

[0078] [Table 2]

[0079] Table 2 shows that the coated avocados of Examples 5-8 were superior to the avocado of Comparative Example 2 in terms of weight retention, hardness, and color change. Therefore, it was confirmed that applying a coating containing a sugar-based surfactant to the surface of avocados can provide a freshness-preserving effect.

[0080] <Test Example 3: Oysters> In Test Example 3, a film was formed on the surface of oysters to evaluate their freshness retention.

[0081] [Example 9] Aqueous coating composition 3-1 was prepared by using "Ryoto® Sugar Ester S-570" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. The aqueous coating composition 3-1 described above was applied to the surface of the oysters by immersion, and dried at room temperature (20-25°C) for 30 minutes to form a film with a thickness of 1.5 μm.

[0082] [Example 10] Aqueous coating composition 3-2 was prepared by using "Ryoto® Sugar Ester S-1170" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 0.5% by mass. Using the aqueous coating composition 3-2 described above, a film with a thickness of 0.15 μm was formed in the same manner as in Example 9.

[0083] [Example 11] Aqueous coating composition 3-3 was prepared by using "Ryoto® Sugar Ester S-1170" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water so that the sugar-based surfactant content was 2% by mass. Using the aqueous coating composition 3-3 described above, a film with a thickness of 0.6 μm was formed in the same manner as in Example 9.

[0084] [Example 12] Aqueous coating compositions 3-4 were prepared by using "Ryoto® Sugar Ester S-1170" manufactured by Mitsubishi Chemical Corporation as a sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. Using the aqueous coating compositions 3-4 described above, a film with a thickness of 1.5 μm was formed in the same manner as in Example 9.

[0085] [Example 13] Aqueous coating compositions 3-5 were prepared by using "Ryoto® Sugar Ester S-1670" manufactured by Mitsubishi Chemical Corporation as a sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. Using the aqueous coating compositions 3-5 described above, a film with a thickness of 1.5 μm was formed in the same manner as in Example 9.

[0086] [Comparative Example 3] Oysters that did not form a coating were designated as Comparative Example 3.

[0087] [Freshness Preservation Evaluation] The freshness preservation of the coated oysters from Examples 9-13 and the oysters from Comparative Example 3 was evaluated based on weight retention rate and hardness retention rate. The change in persimmons as they ripen is easily noticeable, as they become softer. Since consumers generally evaluate the freshness of persimmons by their firmness, we confirmed the freshness preservation effect of persimmons not only by weight retention rate to confirm transpiration suppression, but also by firmness retention rate.

[0088] (Weight maintenance rate) For the coated oysters of Examples 9-13 and the oysters of Comparative Example 3, the weight retention rate ((weight after storage / weight on day 0) × 100 (%)) was calculated after storage at 25°C, 50% RH for 7, 9, and 12 days, using the weight of the oysters before storage (day 0) as the baseline.

[0089] (Hardness retention rate) Six persimmons were prepared for each of the coated persimmons in Examples 9-13 and Comparative Example 3. The percentage of samples that met the following criteria was defined as the hardness retention rate (Reference: Journal of the Japanese Society for Horticultural Science / Vol. 38 (1969) No. 2 Relationship between maturation phenomena and respiration type after fruit harvest (Part 1) Presence or absence of climacteric respiration in persimmon fruit, Takashi Iwata, Katsuya Nakagawa, Kuniyasu Ogata). A: It's hard enough. B: It becomes quite soft overall, but still firm. C: It feels like it's about to fall apart when pressed with a finger, or part of the flesh becomes waterlogged. D: The fruit becomes very soft, or part of the peel is ruptured. Measurements were taken according to this index, and fruits ranked C and D were evaluated as softened (failed).

[0090] Table 3 shows the configurations and evaluation results of Examples 9-13 and Comparative Example 3.

[0091] [Table 3]

[0092] Table 3 shows that the coated oysters of Examples 9-13 were superior to the oysters of Comparative Example 3 in both weight retention and hardness retention. Therefore, it was confirmed that applying a coating containing a sugar-based surfactant to the surface of oysters can provide a freshness preservation effect.

[0093] <Test Example 4: Sudachi> In Test Example 4, a film was formed on the surface of sudachi (a type of citrus fruit) to evaluate its freshness retention.

[0094] [Example 14] Aqueous coating composition 4-1 was prepared by using "Ryoto® Sugar Ester S-1670" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. The aqueous coating composition 4-1 described above was applied to the surface of a sudachi fruit by immersion, and dried at room temperature (20-25°C) for 30 minutes to form a film with a thickness of 1.5 μm.

[0095] [Comparative Example 4] Sudachi that did not form a coating was designated as Comparative Example 4.

[0096] [Freshness Preservation Evaluation] The sudachi with a coating from Example 14 and the sudachi from Comparative Example 4 were evaluated for their freshness retention based on weight retention and color. The color change of sudachi as it ripens is easily noticeable, from green to yellow, and consumers generally evaluate the freshness of sudachi by its color. Therefore, in addition to weight retention to confirm the suppression of transpiration, the freshness preservation effect of sudachi was confirmed by its color.

[0097] (Weight maintenance rate) For the coated sudachi of Example 14 and the sudachi of Comparative Example 4, the weight retention rate ((weight after storage / weight on day 0) × 100 (%)) was calculated after storage at 15°C and 90% RH for 6, 8, and 11 days, using the weight of the sudachi before storage (day 0) as the baseline.

[0098] (color) Five sudachi fruits with the coating from Example 14 and five sudachi fruits from Comparative Example 4 were prepared, and the color change was evaluated. ○ (good): More than 80% of the entire surface is green, equivalent to the blank (Condition 4, Day 0). × (no good): Less than 80% of the entire surface is green, equivalent to the blank (Condition 4, Day 0). The above evaluation was performed four times: before storage (day 0), and after storage at 15°C and 90% RH for 6, 8, and 11 days. The change in color was evaluated according to the following criteria. A: Over 80% of the samples can be rated as ○ (good). B: Over 60% of the samples could be rated as ○ (good), but less than 80%. C: Over 40% of the samples could be rated as ○ (good), but less than 60%. D: More than 20% of the samples could be rated as ○ (good), but less than 40%. E: Less than 20% of the samples can be evaluated as ○ (good).

[0099] Table 4 shows the configuration and evaluation results of Example 14 and Comparative Example 4.

[0100] [Table 4]

[0101] Table 4 shows that the coated sudachi of Example 14 was superior to the sudachi of Comparative Example 4 in both weight retention and color change, confirming that a freshness preservation effect can be obtained by applying a coating containing a sugar-based surfactant to the surface of sudachi.

[0102] <Test Example 5: Water Vapor Barrier Properties> In Test Example 5, a coating was formed on a polyethylene terephthalate film and its water vapor barrier properties were evaluated.

[0103] [Example 15] Aqueous coating composition 5-1 was prepared by using "Ryoto® Sugar Ester S-570" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 2% by mass. A PET film (50 μm thick, manufactured by Toyobo Co., Ltd.: A4160 type) that had been corona-treated on its highly smooth surface was coated with the above aqueous coating composition 5-1 using a #20 bar coater, and dried at room temperature (20-25°C) for 24 hours to form a coating film with a thickness (after drying) of 0.74 μm on the PET film.

[0104] [Example 16] Aqueous coating composition 5-2 was prepared by using "Ryoto® Sugar Ester S-1670" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 2% by mass. Using the aqueous coating composition 5-2 described above, a coating film with a thickness of 0.58 μm was formed in the same manner as in Example 15.

[0105] [Example 17] The coated PET film obtained in Example 16 above was heated at 70°C for 15 minutes and then cooled.

[0106] [Comparative Example 5] Comparative Example 5 was a PET film that did not form a coating.

[0107] [Evaluation of water vapor barrier properties] The water vapor transmission rates of the coated PET films of Examples 15-17 and the PET film of Comparative Example 5 were measured using a DELTAPERM water vapor transmission rate analyzer manufactured by Technolox, in accordance with the JIS K7129-5 method, under conditions of 30°C and 50% RH. Furthermore, for the coated PET films of Examples 15 to 17, the water vapor transmission rate per 1 μm of coating was determined using the following formula.

[0108]

number

[0109] Table 5 shows the configurations and evaluation results of Examples 15-17 and Comparative Example 5.

[0110] [Table 5]

[0111] Table 5 shows that the coated PET films of Examples 15-17 exhibited superior water vapor barrier properties compared to the PET film of Comparative Example 5, confirming that coatings containing sugar-based surfactants possess water vapor barrier properties. Furthermore, in Examples 16 and 17, the water vapor barrier properties changed before and after heat treatment. The sugar-based surfactant (S-1670) used in Examples 16 and 17 has slow crystal growth, so the coating film before heat treatment has a crystalline structure of the sugar-based surfactant, whereas the coating film after heat treatment does not. Therefore, the results from Examples 16 and 17 confirmed that the water vapor barrier properties are further improved when the coating film has a crystalline structure.

[0112] <Test Example 6: Oxygen Barrier Properties> In Test Example 6, a coating was formed on a polyethylene terephthalate film and its oxygen barrier properties were evaluated.

[0113] [Example 18] Aqueous coating composition 6-1 was prepared by using "Ryoto® Sugar Ester S-1170" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 2% by mass. A PET film (50 μm thick, manufactured by Toyobo Co., Ltd.: A4160 type) that had been corona-treated on its highly smooth surface was coated with the above aqueous coating composition 6-1 using a #20 bar coater, and dried at room temperature (20-25°C) for 24 hours to form a coating film with a thickness (after drying) of 0.42 μm on the PET film.

[0114] [Example 19] Aqueous coating composition 6-2 was prepared by using "Ryoto® Sugar Ester S-1170" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. Using the aqueous coating composition 6-2 described above, a coating film with a thickness of 0.56 μm was formed in the same manner as in Example 18.

[0115] [Example 20] The coated PET film obtained in Example 19 above was heated at 70°C for 15 minutes and then cooled.

[0116] [Comparative Example 6] Comparative Example 6 was a PET film that did not form a coating.

[0117] [Oxygen barrier performance evaluation] The oxygen permeability of the coated PET films of Examples 18-20 and the PET film of Comparative Example 6 was measured at 25°C and 50% RH using the MOCON OX-TRAN 2 / 21 oxygen permeability analyzer, in accordance with JIS K7126-2. Furthermore, for the coated PET films of Examples 18-20, the oxygen permeability per 1 μm of coating was determined using the following formula.

[0118]

number

[0119] Table 6 shows the configurations and evaluation results of Examples 18-20 and Comparative Example 6.

[0120] [Table 6]

[0121] Table 6 shows that the coated PET films of Examples 18-20 exhibited superior oxygen barrier properties compared to the PET film of Comparative Example 6, confirming that coatings containing sugar-based surfactants possess oxygen barrier properties. Furthermore, in Examples 19 and 20, the oxygen barrier properties changed before and after heat treatment. The sugar-based surfactant (S-1170) used in Examples 19 and 20 has slow crystal growth, so the coating film before heat treatment has a crystalline structure of the sugar-based surfactant, whereas the coating film after heat treatment does not. Therefore, the results from Examples 19 and 20 confirmed that the oxygen barrier properties are further improved when the coating film has a crystalline structure.

[0122] <Test Example 7: Shine Muscat> In Test Example 7, a film was formed on the surface of Shine Muscat grapes to evaluate their freshness retention.

[0123] [Example 21] Aqueous coating composition 7-1 was prepared by using "Ryoto® Sugar Ester S-1170" manufactured by Mitsubishi Chemical Corporation as a sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. The aqueous coating composition 7-1 described above was applied to the surface of Shine Muscat grapes by immersion, and dried at room temperature (20-25°C) for 30 minutes to form a film with a thickness of 1.5 μm.

[0124] [Comparative Example 7] Comparative Example 7 was a Shine Muscat grape that did not form a coating.

[0125] [Freshness Preservation Evaluation] It is known that the rachis of Shine Muscat grapes turn brown when their freshness deteriorates. Therefore, the freshness retention of the coated Shine Muscat grapes of Example 21 and the Shine Muscat grapes of Comparative Example 7 was evaluated based on the color of the rachis.

[0126] (color) Eight Shine Muscat grapes were prepared from both Example 21 (with a coating) and Comparative Example 7, and the change in the color of the grape stalk was evaluated. ○ (good): More than 80% of the entire surface of the ear rachis is green, the same as the blank (Condition 7, day 0). × (no good): Less than 80% of the entire surface of the cob is green, the same as the blank (the state of Comparative Example 7 on day 0). The above evaluation was performed five times: before storage (day 0), and after storage at 5°C and 50% RH for 13, 15, 18, and 21 days. The change in color was evaluated according to the following criteria. A: Over 75% of the samples can be rated as ○ (good). B: More than 50% of the samples could be rated as ○ (good), but less than 75%. C: More than 25% of the samples could be rated as ○ (good), but less than 50%. D: The percentage of samples that can be evaluated as ○ (good) is greater than 0% and less than 25%. E: No samples were found that could be rated as ○ (good) (0%).

[0127] Table 7 shows the configuration and evaluation results of Example 21 and Comparative Example 7.

[0128] [Table 7]

[0129] Table 7 shows that the coated Shine Muscat grapes of Example 21 showed less change in the color of the rachis compared to the Shine Muscat grapes of Comparative Example 7. This confirms that applying a coating containing a sugar-based surfactant to the surface of Shine Muscat grapes can provide a freshness-preserving effect.

[0130] <Test Example 8: Kyoho Grapes> In Test Example 8, a film was formed on the surface of Kyoho grapes to evaluate their freshness retention.

[0131] [Example 22] Aqueous coating composition 8-1 was prepared by using "Ryoto® Sugar Ester S-1170" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. The aqueous coating composition 8-1 described above was applied to the surface of Kyoho grapes by immersion, and dried at room temperature (20-25°C) for 30 minutes to form a film with a thickness of 1.5 μm.

[0132] [Comparative Example 8] Comparative Example 8 was a Kyoho grape that did not form a coating.

[0133] [Freshness Preservation Evaluation] It is known that Kyoho grapes undergo browning of the rachis as their freshness deteriorates. Therefore, the freshness retention of the Kyoho grapes with a coating in Example 22 and the Kyoho grapes in Comparative Example 8 was evaluated based on the color of the rachis.

[0134] (color) Six Kyoho grapes with a coating were prepared for Example 22, and six Kyoho grapes were prepared for Comparative Example 8. The change in the color of the grape stalk was evaluated. ○ (good): More than 80% of the entire surface of the rachis is green, the same as the blank (Condition 8, day 0). × (no good): Less than 80% of the entire surface of the cob is green, the same as the blank (Condition 8, Day 0). The above evaluation was performed four times: before storage (day 0), and after storage at 5°C and 50% RH for 10, 13, and 16 days. The change in color was evaluated according to the following criteria. A: Over 80% of the samples can be rated as ○ (good). B: Over 60% of the samples could be rated as ○ (good), but less than 80%. C: Over 40% of the samples could be rated as ○ (good), but less than 60%. D: More than 20% of the samples could be rated as ○ (good), but less than 40%. E: Less than 20% of the samples can be evaluated as ○ (good).

[0135] Table 8 shows the configuration and evaluation results of Example 22 and Comparative Example 8.

[0136] [Table 8]

[0137] Table 8 shows that the Kyoho grapes with the coating in Example 22 showed less change in the color of the rachis compared to the Kyoho grapes in Comparative Example 8. This confirms that applying a coating containing a sugar-based surfactant to the surface of Kyoho grapes can provide a freshness-preserving effect.

[0138] <Test Example 9: Strawberries> In Test Example 9, a film was formed on the surface of strawberries (Kaorino variety) to evaluate their freshness retention.

[0139] [Example 23] Aqueous coating composition 9-1 was prepared by using "Ryoto® Sugar Ester P-1570" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. The aqueous coating composition 9-1 described above was applied to the surface of strawberries by immersion, and dried at room temperature (20-25°C) for 30 minutes to form a film with a thickness of 1.5 μm.

[0140] [Example 24] Aqueous coating composition 9-2 was prepared by using "Ryoto® Sugar Ester S-1670" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. Using the aqueous coating composition 9-2 described above, a coating film with a thickness of 1.5 μm was formed in the same manner as in Example 23.

[0141] [Comparative Example 9] A strawberry that did not form a coating was designated as Comparative Example 9.

[0142] [Freshness Preservation Evaluation] The freshness retention of the coated strawberries from Examples 23 and 24, and the strawberries from Comparative Example 9, was evaluated based on gloss retention rate, calyx freshness, and weight retention rate. Since strawberries are known to lose their surface gloss and their calyxes wither as their freshness deteriorates, we confirmed the freshness preservation effect not only by checking the weight retention rate to confirm the suppression of transpiration, but also by checking the gloss retention rate and the freshness of the calyxes.

[0143] (Gloss retention rate) Sixteen strawberries were prepared with coatings from Examples 23 and 24, and sixteen strawberries were prepared with coatings from Comparative Example 9. The change in surface gloss was then evaluated. ○ (good): More than 80% of the entire surface of the strawberry has the same gloss as the blank (Condition 9, day 0). × (no good): Less than 80% of the strawberry surface has the same gloss as the blank (Condition 9, Day 0). The above evaluation was performed four times: before storage (day 0), and after storage at 5°C and 50% RH for 3, 7, and 9 days. The change in surface gloss was evaluated according to the following criteria. A: Over 80% of the samples can be rated as ○ (good). B: Over 60% of the samples could be rated as ○ (good), but less than 80%. C: Over 40% of the samples could be rated as ○ (good), but less than 60%. D: More than 20% of the samples could be rated as ○ (good), but less than 40%. E: Less than 20% of the samples can be evaluated as ○ (good).

[0144] (Freshness of the calyx) Sixteen strawberries were prepared from the coated strawberries of Examples 23 and 24, and sixteen strawberries were prepared from Comparative Example 9, and the change in the freshness of the calyx was evaluated. ○(good): The number of twisted calyx leaves on each strawberry is one or less. × (no good): In a single strawberry, the number of twisted calyx leaves exceeds one. The above evaluation was performed four times: before storage (day 0), and after storage at 5°C and 50% RH for 3, 7, and 9 days. The change in calyx freshness was evaluated according to the following criteria. A: Over 80% of the samples can be rated as ○ (good). B: Over 60% of the samples could be rated as ○ (good), but less than 80%. C: Over 40% of the samples could be rated as ○ (good), but less than 60%. D: More than 20% of the samples could be rated as ○ (good), but less than 40%. E: Less than 20% of the samples can be evaluated as ○ (good).

[0145] (Weight maintenance rate) For the coated strawberries of Examples 23 and 24 and the strawberries of Comparative Example 9, the weight retention rate ((weight after storage / weight on day 0) × 100 (%)) was calculated after storage for 3, 7, and 9 days at 5°C, 50% RH, using the weight of the strawberries before storage (day 0) as the baseline.

[0146] Table 9 shows the configurations and evaluation results of Examples 23, 24 and Comparative Example 9.

[0147] [Table 9]

[0148] Table 9 shows that the coated strawberries of Examples 23 and 24 maintained their gloss and calyx freshness better than the strawberries of Comparative Example 9, and also had superior weight retention. This confirms that applying a coating containing a sugar-based surfactant to the surface of strawberries can provide a freshness-preserving effect.

[0149] <Test Example 10: Partial Coating> In Test Example 10, the efficiency of the coating treatment and its impact on freshness preservation were evaluated when a coating was formed on a portion of avocados, persimmons, and strawberries (Benihoppe variety).

[0150] [Example 25] Aqueous coating composition 10-1 was prepared by using "Ryoto® Sugar Ester S-1670" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 3% by mass. The aqueous coating composition 10-1 described above was applied to the entire surface of the avocado by immersion, and the area was left to stand at room temperature (20-25°C). The time it took for the coating to become non-sticky on the entire surface (drying time) was then observed.

[0151] [Example 26] The avocado was left to stand, and the aqueous coating composition 10-1 was sprayed from above until the surface was wet, forming a coating film on only half of the avocado (more than 50% of the total surface area). The avocado was left to stand at room temperature (20-25°C), and the time until the coating film was no longer sticky on the entire surface (drying time) was observed.

[0152] [Comparative Example 10] Avocado that did not form a film was designated as Comparative Example 10.

[0153] [Freshness Preservation Evaluation (Avocado)] The avocados with coatings from Examples 25-26 and the avocado from Comparative Example 10 were evaluated for freshness retention based on weight retention, hardness, and color, using the same criteria as in Test Example 2.

[0154] [Example 27] A water-based coating composition 10-2 was prepared by using "Ryoto (registered trademark) Sugar Ester S-1170" manufactured by Mitsubishi Chemical Corporation as the sugar-based surfactant, and dissolving it in water to a sugar-based surfactant content of 5% by mass. The aqueous coating composition 10-2 described above was applied to the entire surface of the oyster by immersion, and the oyster was left to stand at room temperature (20-25°C). The time it took for the coating to become non-sticky on the entire surface (drying time) was then observed.

[0155] [Example 28] Persimmons were immersed in the aqueous coating composition 10-2 with the calyx portion facing downwards, and a coating film was formed only around the calyx. The persimmons were left to stand at room temperature (20-25°C), and the time until the coating film was no longer sticky across the entire surface (drying time) was observed.

[0156] [Comparative Example 11] Oysters that did not form a coating were designated as Comparative Example 11.

[0157] [Freshness Preservation Evaluation (Oysters)] The oysters with coatings from Examples 27-28 and the oysters from Comparative Example 11 were evaluated for freshness retention based on weight retention and hardness retention, using the same criteria as in Test Example 3.

[0158] [Example 29] The above aqueous coating composition 10-1 was applied to the entire surface of the strawberries by immersion, and the area was left to stand at room temperature (20-25°C). The time it took for the coating to become non-sticky on the entire surface (drying time) was then observed.

[0159] [Example 30] Strawberries were left to stand, and the aqueous coating composition 10-1 was sprayed from above until the surface was wet, forming a coating film on only half of the strawberry (more than 50% of the total surface area). The strawberries were left to stand at room temperature (20-25°C), and the time until the coating film was no longer sticky on the entire surface (drying time) was observed.

[0160] [Comparative Example 12] A strawberry that did not form a coating was designated as Comparative Example 12.

[0161] [Freshness Preservation Evaluation (Strawberries)] The freshness retention of the coated strawberries from Examples 29 and 30, and the strawberries from Comparative Example 12, was evaluated by weight retention rate.

[0162] (Weight maintenance rate) For the coated strawberries of Examples 29 and 30 and the strawberries of Comparative Example 12, the weight retention rate ((weight after storage / weight on day 0) × 100 (%)) was calculated after storage for 4, 7, and 10 days at 5°C and 80% RH, using the weight of the strawberries before storage (day 0) as the baseline.

[0163] Table 10 shows the configurations and evaluation results of Examples 25-30 and Comparative Examples 10-12.

[0164] [Table 10]

[0165] Table 10 shows that, compared to Examples 25, 27, and 29 in which a coating was formed on the entire avocado, persimmon, and strawberry, Examples 26, 28, and 30 in which a coating was formed on only a portion of the fruit were able to shorten the drying time and demonstrate higher efficiency in the coating process. This is thought to be because when a coating is formed on the entire fruit, liquid accumulates on the underside when left standing, requiring more time for the coating to dry. Furthermore, in Examples 26, 28, and 30, where a coating was formed only on a portion of the fruit, the results were superior to Comparative Examples 10-12 in terms of weight retention, hardness, and color. This confirmed that a freshness preservation effect can be obtained even when the coating is applied only to a portion of the avocado, persimmon, and strawberry.

[0166] From the above test examples 1-4 and 7-10, it was confirmed that the freshness of food can be maintained by applying a coating containing a sugar-based surfactant to the surface of the food. Furthermore, from test example 5, it was confirmed that the coating containing the sugar-based surfactant has high water vapor barrier properties, and it was inferred that the freshness of the food is maintained by this high water vapor barrier property of the coating. In addition, from test example 6, it was confirmed that the coating containing the sugar-based surfactant also has good oxygen barrier properties, and it was inferred that the respiration of fruits and vegetables is suppressed by this oxygen barrier property of the coating, thereby further maintaining the freshness of the food. Furthermore, from test example 10, it was confirmed that the freshness of the food can be maintained while increasing the efficiency of the coating process by forming the coating on only a part of the food. Furthermore, the coating composition for forming the film in this invention has a simple structure and is composed of a sugar-based surfactant that can be used as food, thus having the advantage of being safe from a food hygiene perspective. Furthermore, since the present invention provides gas barrier properties by directly coating food, there is no need to use resin packaging films as in the past, and the invention has the advantage of reducing environmental impact by enabling film-less packaging. [Explanation of Symbols]

[0167] 1. Food distribution system 10 Food 11 Belt conveyor 12-rotation roll 13 Soaking tank 14 Drying oven 15 Evaluation device 16 Vehicles to be shipped

Claims

1. Food products with a coating containing a sugar-based surfactant.

2. The coated food according to claim 1, wherein the sugar-based surfactant is a sucrose fatty acid ester.

3. The coated food according to claim 1 or 2, wherein the lipophilic group of the sugar-based surfactant is a saturated fatty acid.

4. A coated food according to any one of claims 1 to 3, wherein the total amount of the sugar-based surfactant is 100% by mass, and the food contains 50% by mass or more of a sugar fatty acid ester having 3 or fewer fatty acid ester groups.

5. The coated food according to any one of claims 1 to 4, wherein the HLB of the sugar-based surfactant is 5 or higher.

6. The coated food according to any one of claims 1 to 5, wherein the average thickness of the coating is 0.1 μm or more and 10 μm or less.

7. The coated food according to any one of claims 1 to 6, wherein the crystal melting peak temperature of the coating is 40°C or higher and 80°C or lower.

8. The coated food according to any one of claims 1 to 7, wherein the food is a fruit or vegetable.

9. The coated food according to any one of claims 1 to 8, wherein the coating covers only a portion of the food.

10. A coating composition comprising a sugar-based surfactant and an aqueous solvent.

11. The coating composition according to claim 10, wherein the sugar-based surfactant is a sucrose fatty acid ester.

12. The coating composition according to claim 10 or 11, wherein the lipophilic group of the sugar-based surfactant is a saturated fatty acid.

13. The coating composition according to any one of claims 10 to 12, wherein the total amount of the sugar-based surfactant is 100% by mass, and the composition contains 50% by mass or more of a sugar fatty acid ester having three or fewer fatty acid ester groups.

14. The coating composition according to any one of claims 10 to 13, wherein the HLB of the sugar-based surfactant is 5 or higher.

15. The coating composition according to any one of claims 10 to 14, wherein the content of the sugar-based surfactant among the nonvolatile components in the coating composition is 60% by mass or more.

16. The coating composition according to any one of claims 10 to 15, wherein the aqueous solvent is water or alcohol.

17. A film comprising the coating composition according to any one of claims 10 to 16.

18. A method for producing a coated food, comprising the steps of applying a coating composition according to any one of claims 10 to 16 to food, or applying a sugar-based surfactant to food without a solvent.

19. The method for producing a coated food according to claim 18, wherein the coating method is immersion or spraying.

20. A method for producing a coated food according to claim 18 or 19, wherein the coating composition or the sugar-based surfactant is applied to a part of the food.

21. A method for producing a coated food according to claim 18 or 19, comprising applying the coating composition or sugar-based surfactant to the food, and then removing a portion of the applied coating composition or sugar-based surfactant.

22. A method for forming a coating, comprising the steps of applying a coating composition according to any one of claims 10 to 16 to food, or applying a sugar-based surfactant to food without a solvent.

23. The method for forming a coating according to claim 22, wherein the coating method is an immersion method or a spray method.

24. The method for forming a coating according to claim 22 or 23, wherein the coating composition or the sugar-based surfactant is applied to a part of the food.

25. The method for forming a coating according to claim 22 or 23, wherein the coating composition or sugar-based surfactant is applied to food, and then a portion of the applied coating composition or sugar-based surfactant is removed.

26. A method for shipping food, comprising (A) a step of transporting food, (B) a step of forming a coating on food, and (C) a step of inspecting the coated food using an evaluation device, wherein in step (B), the coating is formed by the method described in any one of claims 22 to 25.

27. The method for shipping food according to claim 26, wherein the inspection step (C) includes at least one inspection selected from the group consisting of visual inspection, sugar content inspection, and size inspection.

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