Fresh produce provided with coating, and method for producing fresh produce provided with coating

Abstract

The present invention pertains to a fresh produce provided with a coating. The coating contains a sugar fatty acid ester as a major ingredient. Regarding the heights A and B of absorbance peaks in infrared spectroscopy of the coating on the surface of the fresh, A / B is equal to or more than 0.750. A: An absorbance peak height derived from water at 1635 cm-1 B: An absorbance peak height derived from OH at 3308 cm-1 The present invention addresses the problem of providing a fresh produce in which transpiration of moisture is suppressed while respiration of the fresh produce is appropriately suppressed and which can maintain the marketability thereof for a prolonged period of time by providing, on the fresh produce, a coating that is highly safe, that has oxygen barrier properties, and that has high water-vapor barrier properties. The present invention can also provide a method for stably providing said coating on a fresh produce.

Description

Coated fruits and vegetables, and methods for producing coated fruits and vegetables.

[0001] This invention relates to coated fruits and vegetables, and to a method for producing coated fruits and vegetables.

[0002] In recent years, packaging materials that can maintain the freshness of food during distribution or storage, such as MA (Modified Atmosphere) packaging, have attracted attention. For example, a technology has been proposed to maintain the freshness of food by providing a layer with a freshness-preserving effect on the film used to package food (see Patent Document 1). In addition, a technology has been proposed to maintain the freshness of food by directly applying a quality-preserving agent to foods such as fruits and vegetables (see Patent Documents 2, 3, and 4).

[0003] As a liquid agent for maintaining the freshness of food, Patent Document 5 discloses an agent for preventing damage to the peel of fruits and vegetables, in which a surfactant with an HLB of 5 or less is used as an active ingredient. Since the lipophilic surfactant used in Patent Document 5 is not easily dispersed or dissolved in water, a method is disclosed in which an emulsified solution, emulsified using a hydrophilic emulsifier, is sprayed onto the fruits and vegetables, or the fruits and vegetables are immersed in it, thereby adhering the surfactant with an HLB of 5 or less to the surface of the fruits and vegetables.

[0004] Japanese Patent Publication No. 2001-171058, Japanese Patent Publication No. 2018-134115, Japanese Patent Publication No. 2005-530502, Japanese Patent Publication No. 2018-529627, Japanese Patent Publication No. Hei 8-56564

[0005] In the technology disclosed in Patent Document 1, food may come into contact with the packaging film during distribution or storage, so it is preferable that the layer having a freshness-preserving effect is also highly safe for the human body. Furthermore, from the perspective of waste, reducing the amount of packaging film itself can be cited as an issue.

[0006] Furthermore, the methods disclosed in Patent Documents 2 and 3 had short freshness preservation periods and were not necessarily sufficient to achieve freshness preservation performance. There were also issues such as the materials used being compositions that were not gentle on the human body. On the other hand, as disclosed in Patent Document 4, a method for maintaining the freshness of agricultural products by covering them with a protective coating derived from monoacylglycerides is known. However, while Patent Document 4 describes a desirable thickness in terms of appearance, it does not mention a desirable thickness from the standpoint of maintaining marketability.

[0007] In the liquid formulation disclosed in Patent Document 5, the liquid stability was insufficient, and gelation sometimes occurred during the preparation of the liquid formulation or over time. Furthermore, in the liquid formulation disclosed in Patent Document 5, when applied to food products such as fruits and vegetables, drying took a long time, resulting in poor productivity. In addition, the thickness of the coating was not uniform, resulting in application marks being visible or the surface of the coated food product turning white.

[0008] Therefore, the present invention aims to provide fresh produce that can maintain its marketability for a long period of time by covering it with a coating that is highly safe, has oxygen barrier properties, and has high water vapor barrier properties, thereby appropriately suppressing the respiration of fresh produce and inhibiting moisture evaporation. The present invention also aims to provide a method for stably applying the aforementioned coating to fresh produce.

[0009] The inventors have determined that the infrared absorption spectrum obtained using the total internal reflection (ATR) method on the surface of coated fruits and vegetables is 1635 cm⁻¹. －１ The height A of the absorbance peak is 3308 cm. －１ We found that by setting the A / B ratio to 0.750 or higher at the absorbance peak height B, it becomes possible to appropriately regulate the transpiration and respiration of fruits and vegetables with a coating, thereby maintaining the marketability of the fruits and vegetables for a long period of time. Furthermore, we found that by manufacturing the coating composition for obtaining the aforementioned coating using a specific manufacturing method, the coating composition can be stably prepared, and fruits and vegetables having a coating suitable for maintaining marketability on their surface can be easily obtained. This invention was completed based on the above findings.

[0010] In other words, the present invention has the following aspects: [1] Coated fruits and vegetables, wherein the coating mainly contains sugar fatty acid esters, and the ratio of A / B between the heights A and B of the absorbance peaks of the coating on the surface of the fruits and vegetables in infrared spectroscopy is 0.750 or more. A: 1635 cm －１ Water-derived absorbance peak height B: 3308 cm －１ [2] The coated fruit and vegetable according to [1], wherein the coating is crystalline and has a crystal melting peak temperature of 40°C or more and 80°C or less. [3] The coated fruit and vegetable according to [1] or [2], wherein the fruit and vegetable is any of fruits, fruit vegetables, leafy and stem vegetables, and root vegetables. [4] The coated fruit and vegetable according to any of [1] to [3], wherein the water contact angle of the coating on the surface of the fruit and vegetable is 35° or less. [5] The coated fruit and vegetable according to any of [1] to [4], wherein the sugar fatty acid ester is a sucrose fatty acid ester. [6] A method for producing coated fruit and vegetable, characterized by using a coating composition obtained by heating an aqueous solution with an electrical conductivity of 800 μS / cm or less and a sugar fatty acid ester to 50 to 90°C, and then cooling to 25°C within 90 minutes. [7] A method for producing coated fruit and vegetable according to [6], characterized in that the coating composition further contains a water-soluble organic solvent. [8] The method for producing coated fruits and vegetables according to [7], wherein the water-soluble organic solvent is ethanol. [9] The method for producing coated fruits and vegetables according to any one of [6] to [8], wherein the electrical conductivity of the water used to produce the aqueous solution is 100 μS / cm or less.

[0011] The coated fruits and vegetables of the present invention have a coating that has high water vapor barrier properties and appropriately suppresses respiration, thereby maintaining their marketability for a long period of time. In this case, whether the coated fruits and vegetables are in the desired state can be confirmed by the ATR method, so it can be used for pre-shipment inspection without damaging the coated fruits and vegetables. Furthermore, since the coating with marketability-preserving properties is applied directly to the food in this invention, it does not require plastic packaging materials as in the past, enabling film-less packaging and making a significant contribution to reducing environmental impact.

[0012] The present invention will be described in detail below, but the present invention is not limited to specific embodiments.

[0013] [Coated Fruits and Vegetables] The coated fruits and vegetables of the present invention measured the coating on the surface of the fruits and vegetables at 1635 cm⁻¹ using the ATR method (total internal reflection absorption method), which is one of the measurement techniques in infrared spectroscopy. －１ Let A be the absorbance peak height derived from water, at 3308 cm. －１ When the absorbance peak height originating from OH is denoted as B, the A / B ratio is characterized by being 0.750 or higher. In this case, the values ​​of A and B are determined by dividing the surface area of ​​the fruit or vegetable into eight sections so that they are approximately equal, measuring the A and B values ​​at one location in each section, and calculating the average of the A / B values ​​from the eight locations. Measurement locations should avoid areas with blemishes, the flower-fall area on the opposite side of the stem, and the cork layer of Japanese pears. Furthermore, since the surface of fruit or vegetable does not have a uniform shape, a spectrum with a poor S / N ratio may be obtained due to reasons such as the entire crystal not adhering to the surface of the fruit or vegetable. In such cases, the measurement should be repeated, avoiding the affected area.

[0014] The A / B ratio is 0.750 or higher, and more preferably 0.760 or higher. An A / B ratio of less than 0.750 indicates that moisture evaporation is greatly suppressed. In this case, the permeability of gases other than moisture, such as oxygen and carbon dioxide, is also greatly suppressed. As a result, hypoxic damage occurs. For example, the respiration of fruits and vegetables changes to anaerobic respiration, which does not absorb oxygen, and off-odor substances such as alcohol and acetaldehyde are produced. As a result, even if the weight loss of fruits and vegetables is suppressed, the taste of the fruits and vegetables is impaired, and they cannot maintain their marketability over a long period of time. Regarding hypoxic damage, an example is described on page 89 of Volume 32, Issue 2 of the Journal of the Japanese Society for Food Preservation Science. Furthermore, the A / B ratio of coated fruits and vegetables is preferably 4.000 or lower, more preferably 3.000 or lower, and even more preferably 2.500 or lower. If the A / B ratio is 4.000 or lower, it can be said that the coating has high water vapor barrier properties and the function of appropriately suppressing respiration. Peak B corresponds to 3308 cm. －１ OH is found in various places, such as in hydroxyl groups in coatings and in fruits and vegetables. On the other hand, at 1635 cm, which corresponds to peak A. －１The water in the surface of the fruit and vegetable originates from the produce. In other words, a small A / B ratio indicates that there is little water on the surface of the fruit and vegetable with its protective coating, making it difficult for water vapor to pass through. In such conditions, gases such as oxygen and carbon dioxide also have difficulty passing through, increasing the risk of hypoxic damage to such fruit and vegetable with its protective coating.

[0015] The ATR method requires no pretreatment and measures at room temperature and pressure, allowing for the measurement of the coating formed on the surface of each individual fruit or vegetable. Since there is no risk of changes in the condition of the fruit or vegetable or the coating during pretreatment or measurement, it is suitable for confirming whether the desired coating has been formed. Furthermore, as long as the A / B ratio of the coated fruit or vegetable is within the specified range, the marketability of the fruit or vegetable can be maintained regardless of the coating's composition and thickness. This eliminates the need for complex operations such as changing the measurement method for each coating composition, making it a simple measurement method. Moreover, because the ATR method can test coated fruit or vegetable non-destructively, it can be used for pre-shipment inspections.

[0016] [Confirmation of the presence or absence of a coating] The presence or absence of a coating on fruits and vegetables can be confirmed by washing the fruits and vegetables with 70°C hot water and measuring the washing solution using liquid chromatography or gas chromatography. In addition, if the coating on fruits and vegetables with a coating contains sugar fatty acid esters, the presence or absence of a coating can also be confirmed by measuring the contact angle of water with the surface of the fruits and vegetables using a contact angle meter. It is preferable that the water contact angle of the coating on the surface of the fruits and vegetables is 35° or less. A water contact angle of 35° or less indicates that the sugar fatty acid esters are sufficiently covering the fruit and vegetables and that the effect of the coating is being fully exerted. From the above viewpoint, it is more preferable that the water contact angle is 20° or less, and even more preferable that it is 10° or less.

[0017] [Coating] The coating according to the present invention is not particularly limited as long as it is a coating that exhibits the effects of the present invention, but it is preferable that the coating has water vapor barrier properties and / or oxygen barrier properties in order to significantly exhibit the effects of the present invention. Since it is applied to fresh produce, it is preferable that it be edible in consideration of safety when it is to be consumed. Examples of materials that exhibit these properties include sugar fatty acid esters, polysaccharides, surfactants other than sugar fatty acid esters, polyvinyl alcohol, and clay. These materials may be used individually or in combination of two or more. The coating may be formed by solvent-free coating without a solvent, or it may be formed by a composition containing a solvent. In the present invention, from the viewpoint of safety when it is to be consumed, it is particularly preferable that the coating be formed by a coating agent composition containing a sugar compound of the sugar fatty acid ester and an aqueous solvent. By having a coating formed by such a coating agent composition, the evaporation of moisture is suppressed while respiration is appropriately suppressed, and the marketability of fresh produce is maintained.

[0018] Preferably, the coating is crystalline and has a crystal melting peak temperature of 40°C or higher and 80°C or lower. If the crystal melting peak temperature is 40°C or higher, the stickiness of the resulting coating is suppressed, and if it is 80°C or lower, it becomes easily soluble in aqueous solvents, resulting in good productivity.

[0019] [Sugar Fatty Acid Esters] Sugar fatty acid esters are formed by the esterification of sugars and fatty acids. Because sugar fatty acid esters have a crystalline structure, the resulting coatings are not sticky and have excellent water vapor barrier and oxygen barrier properties.

[0020] The sugar in sugar fatty acid esters may be any of the following: monosaccharides, disaccharides, trisaccharides, tetrasaccharides, polysaccharides, sugar alcohols, and other oligosaccharides. Examples of monosaccharides include pentoses such as ribulose, xylulose, ribose, arabinose, xylose, lyxose, and deoxyribose; and hexoses such as psicose, fructose, sorbose, tagatose, allose, altrose, glucose, mannose, gross, idose, galactose, talose, fucose, fuculose, and rhamnose. Examples of disaccharides include sucrose, lactose, maltose, trehalose, turanose, and cellobiose. Examples of trisaccharides include raffinose, melegitose, and maltotriose. Examples of tetrasaccharides include acarbose and stachyose. Examples of polysaccharides include glycogen, starch, cellulose, dextrin, glucan, fructan, and chitin. Examples of sugar alcohols include sorbitol, erythritol, xylitol, maltitol, lactitol, mannitol, and glycerin, and condensates of these sugar alcohols may also be used. Examples of other oligosaccharides include fructooligosaccharides, galactooligosaccharides, mannan-oligosaccharides, and lactosucrose.

[0021] The constituent fatty acids of the sugar fatty acid ester are preferably derived from 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 it is preferably 12 to 22, more preferably 12 to 18, and even more preferably 14 to 18. Having the carbon atoms within the above range helps to suppress the stickiness of the resulting film. The constituent fatty acids of the sugar fatty acid ester may be saturated or unsaturated fatty acids, but saturated fatty acids are preferred from the viewpoint of easily solidifying at room temperature (20 to 25°C) and suppressing the stickiness of the resulting film. More specifically, examples include lauric acid, myristic acid, pentadecyl acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, etc., among which saturated fatty acids with 12 to 18 carbon atoms are preferred: lauric acid, myristic acid, palmitic acid, and stearic acid, and saturated fatty acids with 14 to 18 carbon atoms are more preferred: myristic acid, palmitic acid, and stearic acid. These saturated fatty acids may be used individually or in combination of two or more. 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 the sugar fatty acid ester can be measured by gas chromatography analysis after isolating the sugar fatty acid ester from the composition and then derivatizing it.

[0022] 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 groups, and sorbitan fatty acid esters have 1 to 4 groups. In the case of sugar fatty acid esters other than glycerin fatty acid esters, from the viewpoint of being dispersible or soluble in aqueous solvents, it is preferable that the total amount of sugar fatty acid esters (monoesters, diesters, or triesters) having 3 or fewer fatty acid ester groups be 50% by mass or more, 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. Also, from the same viewpoint, it is preferable that the total amount of sugar fatty acid esters (hexaesters, heptaesters, octaesters, or more) having 6 or more fatty acid ester groups be 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. Sugar fatty acid esters having six or more fatty acid ester groups do not need to be included, and their content should be 0% by mass or more.

[0023] 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”.

[0024] 《Measurement of Monoesters, Triesters, and Tetraesters and Above》 After dissolving the sample in a fixed amount of tetrahydrofuran (GPC containing stabilizers or industrial grade), the insoluble matter is removed using a 0.5 μm membrane filter to obtain the solution, which is used as the measurement sample, and 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 tryester and the combined peak area for tetraesters and above, and then calculating the ratio to the total peak area of ​​all peaks detected by 43 minutes. The peak area is defined as the area from the start point (rising point) to the end 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 from there.

[0025] <Measurement conditions: Monoesters to triesters and tetraesters and above> Instrument: HLC-8320GPC Detector: Differential refractometer (Tosoh Corporation) Column: TSK-Gel G1000HXL, G2000HXL, G3000HXL, G4000HXL (Tosoh Corporation) Column temperature: 40°C Detector temperature: 40°C Eluent: Tetrahydrofuran (GPC containing stabilizer or industrial grade) Flow rate: 0.8 ml / min Injection volume: 80 μl Measurement time: 50 minutes (Area ratio is calculated based on all peaks detected up to 43 minutes)

[0026] 《Measurement of Tetraesters to Octaesters》 After dissolving the sample in a fixed amount of methanol (reagent grade) / tetrahydrofuran (static HPLC grade) = 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 calculating 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 《Measurement of Monoesters to Triesters and Tetraesters and Above》 above according to the area ratio of tetraesters to octaesters. The peak area is defined as the area from the start point (rising point) to the end 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 points, and the area is calculated from there.

[0027] <Measurement conditions: Tetraester to Octaester> Instrument degasser: DGU-20A (Shimadzu Corporation) Pump: LC-20AD (Shimadzu Corporation) Oven: CTO-20A (Shimadzu Corporation) Detector: RID-20A differential refractometer (Shimadzu Corporation) Column: 150 mm x 4.6 mm i. d.; ODS-2 (GL Sciences Corporation) Column temperature: 40°C Detector temperature: 40°C Eluent: Methanol (reagent grade) / Tetrahydrofuran (stabilizer-free HPLC grade) = 70 / 30 to 50 / 50 (vol / vol) Flow rate: 0.8 ml / min Injection volume: 20 μl Measurement time: 16 minutes

[0028] Other sugar fatty acid esters besides glycerol fatty acid esters are not particularly limited as long as they are suitable for food use, but examples include sucrose fatty acid esters, sorbitan fatty acid esters, glucose fatty acid esters, etc., with sucrose fatty acid esters being preferred from the viewpoint of availability. Note that only one type of sugar fatty acid ester is required; two or more types may be used in combination. When two or more sugar fatty acid esters other than glycerol fatty acid esters are combined, it is preferable that 60% or more by mass of sucrose fatty acid esters are used when the total amount of sugar fatty acid esters is 100% by mass. From the viewpoint of suppressing the stickiness of the resulting film and improving 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 particularly preferably 90% or more by mass. Sugar fatty acid esters may also be used alone as sucrose fatty acid esters; therefore, the above ratio may be 100% or less by mass.

[0029] [Glycerin Fatty Acid Esters] Glycerin fatty acid esters are formed by the esterification of glycerin, a type of sugar alcohol, with a fatty acid. The fatty acids that make up glycerin fatty acid esters are the same as those that make up sugar fatty acid esters, but because glycerin fatty acid esters have a small number of hydroxyl groups and are relatively hydrophilic, it is preferable to set the lower limit of the number of carbon atoms in the fatty acid used in the hydrophobic part to a relatively small range. From this viewpoint, the number of carbon atoms in the fatty acid is preferably 4 or more, more preferably 6 or more, and even more preferably 8 or more. The number of carbon atoms in the fatty acid is preferably 24 or less, more preferably 22 or less, even more preferably 20 or less, particularly preferably 18 or less, and most preferably 16 or less.

[0030] The content of glycerin fatty acid esters (monoesters) having one fatty acid ester group is usually 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 40% by mass or more, when the total amount of glycerin fatty acid esters is taken as 100% by mass. More preferably than this range, 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more. There is no particular upper limit, but it should be 100% by mass or less.

[0031] The content of glycerol fatty acid esters (diesters) having two fatty acid ester groups depends on the content of monoesters and triesters, and is not particularly limited.

[0032] The content of glycerin fatty acid esters (tryesters) having three fatty acid ester groups is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, particularly preferably 20% by mass or less, and most preferably 10% by mass or less, when the total amount of glycerin fatty acid esters is 100% by mass, from the viewpoint of dispersibility in aqueous solvents, viscosity of the composition, and handling. The lower limit is not particularly limited, and it may not be present at all (0% by mass), or it may be present as an impurity of 0.1% by mass or more, or 0.5% by mass or more.

[0033] From the viewpoint of dispersibility in aqueous solvents, viscosity of the composition, and handling, when the total amount of glycerin fatty acid esters is taken as 100% by mass, it is preferable that the total amount of glycerin fatty acid esters with one fatty acid ester group (monoester) and fatty acid esters with two fatty acid ester groups (diester) be 50% by mass or more, 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. Of this, the proportion of monoester when monoesters and diesters are totaled is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, particularly preferably 60% by mass or more, and most preferably 80% by mass or more. There is no particular upper limit, but it is sufficient if it is 100% by mass or less.

[0034] The types and amounts of fatty acids can be analyzed using methods such as column chromatography, gas chromatography, thin-layer chromatography, high-performance liquid chromatography, and colorimetric analysis.

[0035] [Sugar fatty acid esters as surfactants] The sugar fatty acid esters in this invention have a molecular structure derived from sugars, including a sugar alcohol as a hydrophilic group, and a molecular structure derived from fatty acids as a lipophilic group, and therefore also function as surfactants. Surfactants exhibit surface activity that lowers the surface tension of the dissolved solution and are substances that are put into practical use.

[0036] The coated fruits and vegetables of the present invention are preferably formed from a component containing a sugar fatty acid ester as a surfactant. The inclusion of a sugar fatty acid ester enhances wettability and improves the applicability to the target fruits and vegetables. Two or more types of sugar fatty acid esters may be used in combination.

[0037] As surfactants used in the coated fruits and vegetables of the present invention, sugar fatty acid esters other than glycerin fatty acid esters are preferred because they have high water solubility and can be dissolved in a solvent mainly composed of water.

[0038] [Content of Main Component in Coating] The main component in the coating refers to at least one or more compounds selected from sugar fatty acid esters in the coating of the fresh produce with coating. Usually, the total content of the compounds in the coating is 50% or more. From the viewpoint of enhancing water vapor barrier property and oxygen barrier property, the content of sugar fatty acid esters in the coating of the fresh produce with coating of the present invention is preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 90% or more, with 100% by mass as the upper limit.

[0039] <Edibility> The coating of the fresh produce with coating of the present invention preferably has edibility. Edibility means being able to be used for food. From the viewpoint of safety, for compounds approved as food additives, it is preferable to use them so as to satisfy the dosage to have edibility.

[0040] [Method for Producing Fresh Produce with Coating] The method for producing fresh produce with coating of the present invention is characterized by forming a coating on fresh produce using a liquid (coating composition) obtained by heating at least one selected from an aqueous solution having an electric conductivity of 800 μS / cm or less and sugar fatty acid esters to 50 to 90 °C and then cooling to 25 °C within 90 minutes. According to this method, a coating in a form suitable for maintaining the commercial quality can be easily formed on the surface of fresh produce. Here, the aqueous solution may include those in which ionic components contained in the raw material water and components added as sub-components are dissolved in water.

[0041] The type of water used in the production of the aqueous solution is not particularly limited as long as the electrical conductivity of the aqueous solution is 800 μS / cm or less, and examples include ion-exchanged water, distilled water, RO water, purified water, and the like. The electrical conductivity of the water used in the production of the aqueous solution is preferably 100 μS / cm or less, more preferably 80 μS / cm or less, still more preferably 50 μS / cm or less, and particularly preferably 30 μS / cm or less. The electrical conductivity of the aqueous solution is preferably 700 μS / cm or less, more preferably 600 μS / cm or less, still more preferably 500 μS / cm or less, even more preferably 400 μS / cm or less, particularly preferably 300 μS / cm or less, further preferably 100 μS / cm or less, and most preferably 30 μS / cm or less.

[0042] During heating, it may be cooled after maintaining the temperature for a certain period of time. From the viewpoint of enhancing the uniformity of the components in the coating composition, the holding time is preferably 15 minutes or more, more preferably 20 minutes or more, and still more preferably 25 minutes or more. Also, from the viewpoint of productivity, the holding time is preferably 2 hours or less, more preferably 1 hour or less, and still more preferably 45 minutes or less.

[0043] The cooling time is preferably within 90 minutes, more preferably within 60 minutes, still more preferably within 50 minutes, and particularly preferably within 40 minutes. The cooling method is not particularly limited, and examples include a method of cooling in a water bath, a method of cooling by exposing to cold air, a method of passing through a heat exchanger, and the like.

[0044] When the electrical conductivity of the aqueous solution is greater than 800 μS / cm or the cooling time is longer than 90 minutes, the oxygen barrier property of the film formed using the obtained coating composition may become too high, resulting in a decrease in taste due to low oxygen damage. In addition, there may be appearance defects such as whitened portions on the film.

[0045] <Non-volatile component concentration> The concentration of non-volatile components in the coating composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 1.5% by mass or more, particularly preferably 2% by mass or more, and most preferably 3% by mass or more. It is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, particularly preferably 9% by mass or less, and most preferably 8% by mass or less. By setting the non-volatile component concentration within the above range, it becomes easier to form a film with a suitable thickness while appropriately dissolving each component of the coating composition in a water-based solvent. In this invention, "non-volatile component concentration" refers to the concentration of non-volatile components excluding components that volatilize at normal pressure and 105°C or below, such as a water-based solvent, contained in the coating composition.

[0046] <Water-soluble organic solvents> Water-soluble organic solvents may be included in the production of the coating composition. Examples of water-soluble organic solvents include alcohols such as ethanol, isopropanol, ethylene glycol, and glycerin. Water is preferred from the viewpoint of being able to be applied to fruits and vegetables, but from the viewpoint of stability and applicability, the coating composition may contain organic solvents such as the above-mentioned alcohols in addition to water. Ethanol is particularly preferred from the viewpoint of food hygiene. The content of water-soluble organic solvents 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 particularly preferably 5% by mass or less.

[0047] <Other Components> Other components may be included in the coating composition during its manufacture, provided they do not hinder the effects of the present invention. Examples of other components include pH adjusters. From the viewpoint of safe application to fruits and vegetables, the pH is preferably between 4 and 10, and more preferably between 4 and 8. Examples of pH adjusters include acetic acid, lactic acid, citric acid, ammonia, etc.

[0048] [Method for forming the coating] There are no particular limitations on the method for forming the coating on the coated fruits and vegetables of the present invention. Examples include direct application methods such as brush application of the coating composition or curtain coating; immersion methods such as immersion coating; and spraying methods such as spray coating. Of these, the immersion method or spraying method is preferred from the viewpoint of being able to coat fruits and vegetables with a three-dimensional shape relatively uniformly and from the viewpoint of productivity.

[0049] The coating does not necessarily need to cover the entire fruit or vegetable; it may cover only a portion of the fruit or vegetable as long as transpiration and respiration from the fruit or vegetable are suppressed. In this case, the application 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 particularly preferably 50% or more. Furthermore, from the viewpoint of maintaining the marketability of the fruit or vegetable, it is preferable that the coating at least covers the parts where moisture transpiration is high. Examples of parts where moisture transpiration is high include the stomata on the underside of the leaves, the stem, the fruit stalk, the cocoon, the calyx, the calyx, or the roots, or the cut surface at harvest. Moreover, from the viewpoint of maintaining marketability without significantly altering the appearance of the fruit or vegetable, it is preferable to cover only the parts where moisture transpiration is high. Regarding the application method, there is an example described in "Coating Method" by Yuji Harasaki, published by Maki Shoten in 1979.

[0050] [Fresh Produce] As fresh produce in the present invention, for example, fruits such as apples, strawberries, peaches, green plums, oranges, grapefruit, mandarins, sudachi, oysters, figs, strawberries, kiwifruits, grapes, blueberries, bananas, mangoes, melons, papayas, lychees, apricots, avocados, cantaloupes, guavas, nectarines, pears (Japanese pears, European pears, etc.), lemons, plums, etc.; root vegetables such as daikon radishes, carrots, burdocks, bamboo shoots, sweet potatoes, onions, ginger, taros, long yams, etc.; leafy and stem vegetables such as asparagus, cabbages, lettuces, spinach, Chinese cabbages, cauliflowers, broccoli, etc.; fruit vegetables such as tomatoes, eggplants, pumpkins, bell peppers, cucumbers, etc.; wild vegetables such as bracken, Japanese pteridophyta; mushroom fungi such as shiitakes, eringi, beech mushrooms, hon-shimeji mushrooms, enoki mushrooms, maitake mushrooms, etc.; cut flowers such as chrysanthemums, roses, lilies, etc. Among these, fruits, fruit vegetables, leafy and stem vegetables, and root vegetables are particularly suitable, and fruits, fruit vegetables, and leafy and stem vegetables are more suitable.

[0051] [Drying] After the coating composition is applied to fresh produce by a method such as coating, drying of the film may be performed for the purpose of removing the solvent. Examples of drying methods include static drying, blow drying, or heat drying. From the perspective of maintaining the commercial quality of fresh produce, a method of static drying at room temperature (20 - 25°C) or a method of blow drying at room temperature is preferable.

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

[0053] [Method for Measuring the Film of Coated Fresh Produce by Infrared Spectroscopy] The films of the coated fresh produce prepared in the examples and comparative examples were measured by the following method. Apparatus: Fourier transform infrared spectrophotometer (manufactured by JASCO Corporation) Measuring method: ATR method Crystal: Diamond Measurement range: 500 - 4000 cm －１ Incident angle: 45° Resolution: 1 cm －１ Number of accumulations: 16 For the entire spectrum, 4000 cm －１The absorbance was corrected to zero. <Evaluation Criteria> The fruit and vegetable were divided into eight sections so that the surface area was approximately equal, and measurements were taken at one point in each section, at 1635 cm². －１ Let A be the absorbance peak height derived from water, at 3308 cm. －１ The absorbance peak height derived from OH was defined as B, and the average of the A / B values ​​from eight locations was calculated. For Japanese pears (Kosui variety), the measurements were taken on the peel, avoiding the cork layer.

[0054] [Method for Measuring the Contact Angle of Coatings on Coated Fruits and Vegetables] The coatings on the coated fruits and vegetables prepared in the examples and comparative examples were measured using the following method. Using a fully automatic contact angle meter DMo-702 (manufactured by Kyowa Interface Science Co., Ltd.), water was filled into a syringe to create a 2 μL droplet, which was then applied to the surface of the coating on the coated fruits and vegetables. The contact angle was measured 10,000 milliseconds after the water was applied using the contact angle meter. Measurements were taken at three locations, and the average value was calculated. Note that when the water contact angle was 10° or less, it was difficult to read the value, so it was indicated as 10 or less.

[0055] [Method for evaluating marketability] Three coated fruits and vegetables were prepared for each coating composition, with a film formed using the coating compositions described below. These were stored under the conditions described in Tables 3 to 6. Various tests were then conducted. Uncoated fruits and vegetables without a film were stored under the same conditions and various tests were conducted. These were designated as Test Examples 1 to 4. <Presence or absence of hypoxia damage> - Taste A taste test was conducted with three subjects. Using three test specimens, a good rating was given if all three subjects did not notice any discomfort in taste or smell, and a bad rating was given if any subject noticed any discomfort. - Brown spots on the peel Japanese pear (Kosui) and lemon were observed for the presence or absence of brown spots on the peel. A good rating was given if two or more of the three specimens did not have brown spots on the peel, and a bad rating was given if one or fewer did.

[0056] <Presence or absence of freshness deterioration> - Hardness of the flesh The hardness of the flesh of the Japanese pear (Kosui) was measured. Three samples of flesh were taken from near the center in the vertical direction. This was done for each of the three test specimens. Using a tabletop tensile and compression tester (Force Tester) MCT-2150 (manufactured by A&D Co., Ltd.), a cylindrical plunger with a diameter of 3 mm was inserted from the center outward at a speed of 60 mm / min and the maximum value was read. The average value was taken as the hardness of the flesh. A higher value indicates that the hardness has been maintained. - Texture A texture test was conducted on three subjects using the Japanese pear (Kosui). Using three test specimens, a good rating was given if all three felt that the pear had the original crisp texture, and a bad rating was given if any of them felt that the texture was unusual. - Skin color The skin color of the Japanese pear (Kosui) was tested. Using three test specimens, the peel near the center in the vertical direction was scored from 1 point (green) to 6 points (brown) using a color chart for Kosui pears developed at the Ministry of Agriculture, Forestry and Fisheries Fruit Tree Experiment Station, and the average value was calculated. A lower number indicates that the green color has been maintained better. Appearance: The appearance of Japanese pears (Kosui) was observed. If two or more of the three specimens retained their green color, it was given a good rating; if one or fewer retained their green color, it was given a bad rating. Weight loss rate: The weight loss rate was measured for lemons, sudachi, and bananas. The average weight loss rate before and after the storage period of the three test specimens was calculated.

[0057] The materials used are as follows: S-1170: Sucrose stearate ester, manufactured by Mitsubishi Chemical Corporation, "Ryoto (registered trademark) Sugar Ester S-1170" S-100P: Glycerin fatty acid ester, manufactured by Riken Vitamin Co., Ltd., "Rikemar (registered trademark) S-100P" Sodium stearate: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0058] To prepare coating composition 1, 91 parts by mass of an aqueous solution with an electrical conductivity of 1 μS / cm, measured using an AS650 conductivity meter (manufactured by AS ONE Corporation) with deionized water, 5 parts by mass of ethanol, and 4 parts by mass of sucrose fatty acid ester (S-1170) were added to a glass bottle. The mixture was heated in a 70°C water bath for 30 minutes. After that, the mixture was cooled in a room temperature water bath (20-25°C, the same applies below) to prepare coating composition 1. The time to reach room temperature was 30 minutes.

[0059] Preparation of Coating Composition 2: Coating composition 2 was prepared in the same manner as coating composition 1, except that an aqueous solution with an electrical conductivity of 600 μS / cm was used instead of an aqueous solution with an electrical conductivity of 1 μS / cm. The time to reach room temperature was 30 minutes.

[0060] Preparation of Coating Composition 3: Coating composition 3 was prepared in the same manner as coating composition 1, except that glycerin fatty acid ester (S-100P) and sodium stearate were used in a mass ratio of 93:7 instead of sucrose fatty acid ester, and an ice bath was used instead of a room temperature water bath. The time to reach room temperature was 10 minutes.

[0061] Preparation of Coating Composition 4: Coating composition 4 was prepared in the same manner as coating composition 1, except that an aqueous solution with an electrical conductivity of 850 μS / cm was used instead of an aqueous solution with an electrical conductivity of 1 μS / cm. The time to reach room temperature was 30 minutes.

[0062] Preparation of coating composition 5: Coating composition 5 was prepared in the same manner as coating composition 3, except that instead of an ice bath, the heater power to a 70°C water bath was turned off and it was allowed to cool naturally. The time it took to reach room temperature was 150 minutes.

[0063] Preparation of Coated Produce The coating composition described above was applied to the surface of the produce listed in Table 1 by immersion, and dried overnight at room temperature to form a coating. The A / B ratio obtained from the measured ATR of each coated produce is shown in Table 1.

[0064]

[0065] Table 2 shows the water contact angle (in degrees) for each type of coated produce.

[0066]

[0067] Table 3 shows the results of the evaluation of the marketability of Japanese pears (Kosui variety).

[0068]

[0069] Furthermore, only taste and texture tests were conducted on fruits and vegetables (Japanese pears (Kosui variety)) coated with coating composition 1. Both results were rated as good.

[0070] Table 4 shows the results of the evaluation of the marketability of lemons.

[0071]

[0072] Furthermore, only a taste test was conducted on the coated fruits and vegetables (lemons) using coating composition 1. The result was a good rating.

[0073] Table 5 shows the evaluation results for the marketability of sudachi.

[0074]

[0075] Table 6 shows the results of the evaluation of the marketability of bananas.

[0076]

[0077] Furthermore, only a taste test was conducted on the coated fruits and vegetables (bananas) using coating composition 1. The result was a good rating.

[0078] The results shown in Table 3 indicate that coated Japanese pears, regardless of the type of coating composition, can be stored without over-ripening compared to uncoated Japanese pears. Furthermore, Examples 1 and 2, with an A / B ratio of 0.750 or higher as defined by the peak height of the ATR, showed no abnormalities in taste or smell, and no brown spots on the peel, indicating that they could be stored without hypoxic damage. Therefore, it was found that the coated fruits and vegetables of Examples 1 and 2 could be stored for a long period without a decrease in marketability. The results shown in Tables 4, 5, and 6 indicate that coated lemons, sudachi, and bananas could be stored with less weight loss compared to uncoated ones. Furthermore, Examples 3 to 7, with an A / B ratio of 0.750 or higher, showed no abnormalities in taste or smell, and no brown spots on the peel, indicating that they could be stored without hypoxic damage. Therefore, it was found that the coated fruits and vegetables of Examples 3 to 7 could be stored for a long period without a decrease in marketability.

[0079] The coated fruits and vegetables of the present invention have a coating that has high water vapor barrier properties and appropriately suppresses respiration, thereby maintaining their marketability for a long period of time. In addition, whether the coated fruits and vegetables are in the desired condition can be confirmed by the ATR method, so it can be used for pre-shipment inspection without damaging the coated fruits and vegetables.

Claims

1. Coated fruits and vegetables, wherein the coating mainly contains sugar fatty acid esters, and the ratio of A / B between the heights of the absorbance peaks A and B of the coating on the surface of the fruits and vegetables measured by infrared spectroscopy is 0.750 or higher. A: 1635 cm －１ Water-derived absorbance peak height B: 3308 cm －１ Absorbance peak height derived from OH 2. The coated fruit and vegetable according to claim 1, wherein the coating is crystalline and has a crystal melting peak temperature of 40°C or higher and 80°C or lower.

3. The coated fruit and vegetable according to claim 1 or 2, wherein the fruit and vegetable is any of the following: fruit, fruit vegetables, leafy and stem vegetables, and root vegetables.

4. The coated fruit or vegetable according to claim 1 or 2, wherein the water contact angle of the coating on the surface of the fruit or vegetable is 35° or less.

5. The coated fruit and vegetable according to claim 1 or 2, wherein the sugar fatty acid ester is a sucrose fatty acid ester.

6. A method for producing coated fruits and vegetables, characterized by using a coating composition obtained by heating an aqueous solution with an electrical conductivity of 800 μS / cm or less and a sugar fatty acid ester to 50 to 90°C, and then cooling it to 25°C within 90 minutes.

7. The method for producing coated fruits and vegetables according to claim 6, wherein the coating composition further comprises a water-soluble organic solvent.

8. The method for producing coated fruits and vegetables according to claim 7, wherein the water-soluble organic solvent is ethanol.

9. The method for producing coated fruits and vegetables according to claim 6 or 7, wherein the electrical conductivity of the water used to produce the aqueous solution is 100 μS / cm or less.

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