Method for preserving vegetables and fruits

Abstract

To provide a preservation method capable of determining conditions such as a temperature at the time of preservation and a preservation period corresponding to an objective storage period.SOLUTION: In the method for preserving vegetables and fruits, the preservation conditions of vegetables and fruits are determined on the basis of a preliminarily obtained maturity degree relation showing the relation between the preservation time from harvesting to the perfect maturation (deterioration) of quality and the maturity degree.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for preserving fruits and vegetables. [Background technology]

[0002] When fruits and vegetables are harvested, they are separated from the trees and ground that provide them with moisture and nutrients, and as a result, they are unable to maintain their condition in the atmosphere immediately after harvest, resulting in a decline in quality. The deterioration of the quality of fruits and vegetables after harvest is caused by water loss due to evaporation from the outer surface of the fruit and vegetables into the atmosphere, gas exchange (respiration) caused by oxygen diffusing from the atmosphere into the fruit and vegetables, aging and over-ripening due to these factors, and physical damage to the surface of the fruit and vegetables.

[0003] In response to the above-mentioned situation, the present inventors have proposed a composition capable of preserving the freshness of foods such as fruits and vegetables, a coated food, a method for producing a coated food, a coating formation method, and a method for shipping food (see Patent Document 1). The coated food described in Patent Document 1 has a coating with high water vapor barrier properties, which can suppress evaporation from the food, thereby preserving freshness for a long period of time. Furthermore, because the coating also has oxygen barrier properties, it can also suppress aging due to respiration, particularly in fruits and vegetables. The coated food described in Patent Document 1 is extremely effective in preserving freshness, and is particularly effective when the storage period is relatively short. However, there are cases where longer storage periods are required, and refrigeration or special packaging is sometimes used as an approach to prevent deterioration over long periods, maintain quality, and extend the life of fruits and vegetables.

[0004] Temperature control is important for maintaining quality in refrigeration, and insufficient control can result in damage to the product or loss of quality. In particular, for fruits and vegetables that are prone to deterioration in quality due to chilling damage caused by low-temperature storage such as refrigeration, depending on the refrigeration conditions, their quality can deteriorate rapidly when they are returned to room temperature from refrigerated storage.

[0005] Ethylene is also known to be a factor in the deterioration of fruit and vegetables, and it is known that it is important to control the amount of ethylene produced within the fruit and vegetables and the conditions under which the fruit and vegetables are exposed to ethylene from the outside (concentration and time). 1-MCP (1-methylcyclopropene) is known as an ethylene inhibitor, and attempts have been made to reduce the effects of ethylene by treating the fruit and vegetables with 1-MCP and using modified atmosphere (MA) packaging (see, for example, Non-Patent Document 1). Special packaging such as MA packaging is useful as a method of preserving fruits and vegetables, and is expected to be even more effective when combined with the above-mentioned low-temperature storage. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2022 / 080444 publication [Non-patent literature]

[0007] [Non-Patent Document 1] Hort. Res. (Japan), 2021, 20 (4), 455-461 Summary of the Invention [Problem to be solved by the invention]

[0008] Under the circumstances described above, it is important to have a preservation method that takes into consideration the transportation process from harvesting to displaying the fruits and vegetables in stores in an optimal state so that the fruits and vegetables can be displayed in the best possible condition for consumers to purchase. Specifically, it is necessary to specify the storage temperature, time, and conditions for returning the fruits and vegetables from a low temperature to room temperature for low-temperature storage for each product. Therefore, an object of the present invention is to propose a storage or transportation method that allows selection of refrigerated storage or room temperature storage depending on the desired storage period, and further allows determination of conditions such as storage temperature and storage period. [Means for solving the problem]

[0009] As a result of extensive research aimed at solving the above problems, the present inventors have found that it is possible to determine optimal storage conditions for fruits and vegetables by previously obtaining a maturity relationship that represents the relationship between the storage time from harvest until complete maturity (deterioration) of the quality and the maturity. The present invention was completed based on this finding. That is, the present invention relates to the following [1] to

[10] .

[0010] [1] A method for storing or transporting fresh produce, in which storage conditions are determined based on a previously obtained maturity relationship that shows the relationship between the storage time from harvest until the quality is fully matured (deteriorated) and the maturity level. [2] The method for storing or transporting fruits and vegetables described in [1] above, wherein the maturity relationship is obtained by changing at least the holding time from harvest and the storage temperature. [3] The method for storing or transporting fruits and vegetables described in [1] or [2] above, wherein the maturity relationship is obtained by changing the holding time at room temperature from harvest, the refrigeration temperature and time, and the holding time at room temperature after refrigeration, and then fitting the results using an S-shaped function. [4] The method for storing or transporting fruits and vegetables according to [3] above, wherein the S-shaped function is any one of a sigmoid function, a Gompertz function, and a Gudermann function. [5] The method for storing or transporting fruits and vegetables according to [4] above, wherein the S-shaped function is a sigmoid function. [6] The method for storing or transporting fruits and vegetables according to any one of [1] to [5] above, wherein at least a storage temperature and a storage period are determined as the storage conditions. [7] The method for storing or transporting fruits and vegetables according to any one of [1] to [6] above, wherein the fruits and vegetables are coated with a surfactant-containing coating. [8] The method for storing or transporting fruits and vegetables according to any one of [1] to [7] above, wherein the fruits and vegetables are packaged in modified atmosphere packaging. [9] The method for preserving or transporting fruits and vegetables according to [8] above, wherein the gas contains 1-methylcyclopropene.

[10] The method for preserving or transporting fruits and vegetables according to any one of [1] to [9] above, wherein the fruits and vegetables are susceptible to chilling damage. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a storage or transportation method in which conditions such as storage temperature and storage period can be determined according to the desired storage period. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a graph showing the relationship between maturity and the amount of fruit and vegetables to which aqueous composition 1 under storage condition 1 was applied (stored at 20° C.). [Figure 2] 10 is a graph showing the relationship between maturity and the temperature of fruits and vegetables to which aqueous composition 1 was applied under storage condition 2 (refrigerated storage at 0° C. and then returned to 20° C.). [Figure 3] 1 is a graph showing the relationship between maturity and storage condition 1 of fruits and vegetables to which aqueous composition 1 was not applied (stored at 20° C.). [Figure 4] 10 is a graph showing the relationship between maturity and the temperature of fruits and vegetables to which Aqueous Composition 1 was not applied under Storage Condition 2 (refrigerated storage at 0° C. and then returned to 20° C.). [Figure 5] 1 is a graph showing the relationship between maturity and storage conditions 3 to 6 for fruits and vegetables to which aqueous composition 1 was not applied (refrigerated storage at 0° C., then returned to 20° C.). [Figure 6] FIG. 1 is a diagram showing the results of calculations in Example 1. [Figure 7] FIG. 10 is a diagram showing the results of calculations in Example 2. [Figure 8] FIG. 10 is a diagram showing the results of calculations in Example 3. [Figure 9] FIG. 10 is a diagram showing the results of calculations in Example 4. [Figure 10] FIG. 10 is a diagram showing the results of calculations in Example 5. [Figure 11] FIG. 10 is a diagram showing the results of calculations in Example 6.

[0013] Hereinafter, embodiments of the present invention will be described in more detail. However, the description of the constituent elements described below is an example of an embodiment of the present invention. The present invention is not limited to these contents and can be implemented with various modifications within the scope of the gist thereof.

[0014] [Method for storing or transporting fresh fruits and vegetables] The method for storing or transporting fresh fruits and vegetables of the present invention is characterized in that the storage or transport conditions of fresh fruits and vegetables are determined based on a maturity relationship representing the relationship between the storage time and the maturity from the time of harvest until the quality is completely mature (deteriorated), which is obtained in advance.

[0015] <Maturity relationship> The maturity relationship is obtained by changing at least the holding time from harvest and the storage temperature to obtain a quantified state of the maturity of fresh fruits and vegetables. More specifically, it is obtained by changing the holding time at a specific temperature from harvest, the temperature and time in cold storage, and the holding time at room temperature after cold storage. And the relationship showing the storage period and the state of maturity of fresh fruits and vegetables obtained based on these data is the maturity relationship. The maturity relationship may be a function fitted using a sigmoid function. By obtaining the maturity relationship in advance for specific fresh fruits and vegetables, it becomes possible to predict the state of the fresh fruits and vegetables after a specific temperature and a specific storage period have elapsed.

[0016] <Sigmoid function> The sigmoid function is a general term for functions that monotonically increase by drawing a curve like an alphabet S stretched diagonally. Examples of sigmoid functions include the logistic function, the Gompertz function, and the Goodallman function. A function that adopts a specific coefficient as the coefficient of the logistic function is the sigmoid function. Among these, the sigmoid function and the Gompertz function are preferred, and the sigmoid function is more preferred. The Gompertz function was devised as a function showing a mortality curve and is considered applicable to the deterioration of the quality of fresh fruits and vegetables. On the other hand, it is considered that a correlation closer to the actual situation can be obtained for the maturity relationship by using the sigmoid function.

[0017] (sigmoid function) The sigmoid function is a type of logistic function. The logistic function is a curve used to approximately describe the growth process of living organisms. This curve shows that the growth rate of something increases the further it is from saturation and decreases the closer it is to saturation, and is expressed by the following equation (1):

[0018]

number

[0019] In the above equation (1), x(t) is a quantity that represents the state at time t, and K, α, and β are constants. This curve is drawn starting from 0 and approaching the saturation point K infinitely. Here, when K=1, r=a, and t0=t, the logistic function becomes a sigmoid function. The sigmoid function is defined as follows:

[0020]

number

[0021] The sigmoid function is also a cumulative frequency representation of a normally distributed occurrence. Therefore, since biological behavior itself is expected to generally follow a normal distribution, it is thought that the sigmoid function, which represents a normal distribution as a cumulative frequency, can be applied to maturity relationships.

[0022] The above-mentioned S-shaped function can determine storage conditions according to the type of fruit or vegetable. More specifically, it can determine at least the storage temperature and storage period for the fruit or vegetable. Since the shape of the sigmoid function is similar to that of other S-shaped functions, when fitting actually acquired data to obtain a maturity relationship, the functions listed above as sigma-type functions rather than the sigmoid function may result in a smaller error from the actually acquired data. Therefore, any of the functions listed above may be used as the S-shaped function. The preferred S-shaped functions are those listed above.

[0023] <Fruits and vegetables> Fruits and vegetables that are the subject of the present invention are not particularly limited, and examples thereof include citrus fruits such as apples, cherries, peaches, blue plums, oranges, grapefruits, mandarins, sudachi, and lemons, persimmons, figs, strawberries, kiwifruits, grapes, blueberries, bananas, mangoes, melons, papayas, lychees, apricots, avocados, cantaloupes, guavas, nectarines, pears (Japanese pears, European pears, etc.), plums, and pineapples; radishes; Examples include earthen vegetables such as carrots, burdock, bamboo shoots, sweet potatoes, onions, ginger, taro, and Chinese yams; leafy vegetables such as asparagus, cabbage, lettuce, spinach, Chinese cabbage, cauliflower, broccoli, and green beans; fruit vegetables such as tomatoes, eggplants, pumpkins, bell peppers, cucumbers, and potatoes; wild vegetables such as bracken and fern; fungal mushrooms such as shiitake mushrooms, king oyster mushrooms, buna-shimeji mushrooms, hon-shimeji mushrooms, enoki mushrooms, and maitake mushrooms; and cut flowers such as chrysanthemums, roses, and lilies.

[0024] Among these, the present invention is preferably applied to fruits and vegetables that are susceptible to chilling damage. Fruits and vegetables that are susceptible to chilling damage are difficult to store, and it is particularly important to determine the conditions for both low-temperature storage and room-temperature storage. According to the present invention, it is possible to determine the optimal storage method even for fruits and vegetables that are susceptible to chilling damage. Fruits and vegetables susceptible to chilling damage are agricultural products that are sensitive to the drop in humidity that accompanies low temperatures and suffer damage due to low temperature stress. The optimum storage temperature range is approximately 8 to 12°C, and certain agricultural products that fall into this category include tomatoes, eggplants, cucumbers, green beans, sweet potatoes, plums, potatoes, pumpkins, bananas, lemons, grapefruit, pineapples, mangoes, papayas, and avocados.

[0025] (Fruits and vegetables with a film) The fruits and vegetables of the present invention are preferably coated with a surfactant-containing coating, which can prevent deterioration of the fruits and vegetables, maintain their quality, and extend their shelf life. Furthermore, by combining this with the preservation method of the present invention, it becomes possible to further maintain the freshness of fruits and vegetables. The method for forming the coating is not particularly limited as long as the coating is formed using a surfactant, and examples thereof include direct application methods such as brush coating and curtain coating; immersion methods such as impregnation coating; and spraying methods such as spray coating. Of these, the immersion method or the spraying method is preferred from the viewpoint of being able to coat three-dimensional fruits or vegetables relatively uniformly and from the viewpoint of productivity. The coating liquid composition may be solvent-free as long as it can form a coating on fruits and vegetables. It is preferable to use it dissolved in a solvent, since this facilitates the formation of a coating. The solvent is not particularly limited as long as it dissolves the surfactant, but considering that it is edible, water, ethanol, or a mixed solvent thereof is preferred. It may also be used as an aqueous composition using a mixed solvent of water and ethanol.

[0026] <Surfactant> The surfactant used in the present invention is not particularly limited as long as it exhibits the effects of the present invention, and may be any substance that has a hydrophilic portion and a lipophilic portion in its molecular structure, is amphiphilic, and has surface activity. The surfactant may be in any form, such as powder, solid, liquid, or paste, but is preferably soluble in water. A low-molecular-weight surfactant is preferred, with a molecular weight of 3,000 or less, more preferably 2,000 or less. The smaller the molecular weight of the surfactant, the greater the number of moles per mass, and the greater the number of molecules that contribute to emulsion stability. While there is no particular lower limit for the molecular weight of the surfactant, it is usually 200 or more because the molecular structure contains both a hydrophilic portion and a lipophilic portion.

[0027] Examples of surfactants include lecithin, lysolecithin, monoglycerin organic acid fatty acid esters, fatty acid salts, monoalkyl sulfates, alkyl polyoxyethylene sulfates, alkyl benzene sulfonates, monoalkyl phosphates, alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, alkyl benzyl dimethyl ammonium salts, alkyl dimethyl amine oxide, and alkyl carboxybetaine, which have an ionic hydrophilic portion; and sugar fatty acid esters such as sucrose fatty acid esters, glycerin fatty acid esters, polyglycerin fatty acid esters (diglycerin fatty acid esters, triglycerin fatty acid esters, decaglycerin fatty acid esters, etc.), sorbitan fatty acid esters, polysorbates, propylene glycol fatty acid esters, saponin, polyoxyethylene alkyl ethers, fatty acid diethanolamides, and alkyl monoglyceryl ethers, which have a nonionic hydrophilic portion. These can be used alone or in combination of two or more.

[0028] Among the above surfactants, food emulsifiers that can be used in foods and drinks are preferred, and among food emulsifiers, those that have been confirmed to be safe for consumption and that are soluble in water are preferred. Examples include lecithin and lysolecithin, monoglycerin organic acid fatty acid esters, sucrose fatty acid esters, glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, polysorbates, propylene glycol fatty acid esters, and saponins. Among these, lysolecithin, monoglycerin organic acid fatty acid esters, sugar fatty acid esters such as sucrose fatty acid esters, glycerin fatty acid esters, and polysorbates are preferred because of their high solubility in water, with sugar fatty acid esters and glycerin fatty acid esters being more preferred, and sugar fatty acid esters such as sucrose fatty acid esters being most preferred.

[0029] (sugar fatty acid ester) Sugar fatty acid esters are formed by esterifying sugars and fatty acids.

[0030] The sugar in the sugar fatty acid ester may be any of 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, gulose, idose, galactose, talose, fucose, fuculose, and rhamnose. Examples of disaccharides include sucrose (cane sugar), lactose, maltose, trehalose, turanose, cellobiose, and the like. Examples of trisaccharides include raffinose, melezitose, 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. Other oligosaccharides include fructooligosaccharides, galactooligosaccharides, mannanoligosaccharides, lactosucrose, and the like.

[0031] 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 from 12 to 22, more preferably from 12 to 18, and even more preferably from 14 to 18. When the number of carbon atoms is within the above range, the stickiness of the resulting coating can be suppressed. 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 to 25° C.) and the resulting coating is less sticky. More specific examples include lauric acid, myristic acid, pentadecylic acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, etc., and among these, lauric acid, myristic acid, palmitic acid, and stearic acid, which are saturated fatty acids having from 12 to 18 carbon atoms, are preferred, and myristic acid, palmitic acid, and stearic acid, which are saturated fatty acids having from 14 to 18 carbon atoms, are more preferred. These saturated fatty acids may be used alone 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, and it is sufficient that 60% by mass or more of the constituent fatty acids in the sugar fatty acid ester are the above-mentioned suitable constituent fatty acids. From the viewpoint of suppressing stickiness of the resulting coating, this ratio is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. There is no particular upper limit, but it is sufficient as long as it is 100% by mass or less. The fatty acid composition of the sugar fatty acid ester can be measured by isolating the sugar fatty acid ester from the composition, derivatizing it, and then analyzing it by gas chromatography.

[0032] The number of fatty acid ester groups in sugar fatty acid esters varies depending on the number of hydroxyl groups capable of forming an ester bond in the molecular structure of the sugar, which is a hydrophilic group; for example, 1 to 8 for sucrose fatty acid esters and 1 to 4 for sorbitan fatty acid esters. From the viewpoint of being dispersible or soluble in aqueous solvents, when the total amount of the sugar-based surfactant is taken as 100% by mass, it preferably contains sugar fatty acid esters (monoesters, diesters, or triesters) having three or less fatty acid ester groups in an amount of 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 as long as it is 100% by mass or less. From the same viewpoint, when the total amount of the sugar-based surfactant is taken as 100% by mass, the sugar-based surfactant preferably contains 30% by mass or less of sugar fatty acid esters having 6 or more fatty acid ester groups (hexaesters, heptaesters, octaesters, or more). 20% by mass or less is more preferable, and 10% by mass or less is even more preferable. The sugar fatty acid esters having 6 or more fatty acid ester groups do not have to be contained, and the content thereof may be 0% by mass or more.

[0033] The content ratio by number of fatty acid ester groups can be measured after isolating the sugar fatty acid ester 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 in the FAO JECFA Monographs 7 (2009), "Sucrose Oligoesters Type I" and "Sucrose Oligoesters Type II," prepared at the 71st JECFA meeting (2009) and published in FAO JECFA Monographs 7 (2009).

[0034] <Measurement of monoesters, triesters, and tetraesters or higher> A sample is dissolved in a fixed amount of tetrahydrofuran (stabilizer-containing GPC or industrial grade), and the solution is filtered through a 0.5 μm membrane filter to remove insoluble matter. This solution is used as the measurement sample and subjected to high-performance liquid chromatography under the following conditions. The composition ratio is calculated by calculating the peak areas of the monoester to triester individually and the combined peak area of ​​tetraester and above, and then calculating the ratio to the total peak area of ​​all peaks detected up to 43 minutes. The peak area is the area from the start point (rising point) to the end point (falling point) of each peak. When two or more peaks are adjacent and the start and end points are unknown, the points where the data between the peaks is smallest are used as the start and end points to calculate the area.

[0035] <Measurement conditions: monoesters to triesters and tetraesters and above> Apparatus: HLC-8320GPC Detector: Differential refractometer (Tosoh Corporation) Column: TSK-Gel G1000HXL, G2000HXL, G3000HXL, G4000HXL (Tosoh Corporation) Column temperature: 40℃ Detector temperature: 40℃ Eluent: Tetrahydrofuran (stabilized GPC 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)

[0036] <Measurement of tetraesters to octaesters> A sample is dissolved in a fixed amount of methanol (special reagent grade) / tetrahydrofuran (stabilizer-free HPLC grade) = 20 / 80 (vol / vol), and the solution, after removing insoluble matter with a 0.45 μm membrane filter, is used as the measurement sample and subjected to high performance liquid chromatography under the following conditions: The composition ratio of tetraesters to octaesters is calculated by calculating the peak area of ​​each tetraester to octaester individually, calculating the ratio to the total peak area of ​​tetraesters to octaesters, and then proportionally dividing the area ratio of tetraesters and above determined in the above <<Measurement of monoesters to triesters and tetraesters and above>> by the area ratio of tetraesters to octaesters. The peak area is the area from the start point (rising point) to the end point (falling point) of each peak. When two or more peaks are adjacent and the start and end points are unknown, the points where the data between the peaks is smallest are used as the start and end points to calculate the area.

[0037] <Measurement conditions: tetraester to octaester> Device 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 id; ODS-2 (GL Sciences) Column temperature: 40℃ Detector temperature: 40℃ Eluent: Methanol (special reagent grade) / tetrahydrofuran (stabilizer-free HPLC grade) = 70 / 30 to 50 / 50 (vol / vol) Flow rate: 0.8ml / min Injection volume: 20μl Measurement time: 16 minutes

[0038] The sugar fatty acid ester is not particularly limited as long as it can be used in foods, and examples thereof include sucrose fatty acid esters, sorbitan fatty acid esters, glucose esters, etc., with sucrose fatty acid esters being preferred from the viewpoint of easy availability. The sugar-based surfactant does not need to be only one type, and two or more types may be used in combination. When two or more types are combined, it is preferable that sucrose fatty acid esters account for 60% by mass or more when the total amount of sugar-based surfactants is 100% by mass. From the viewpoints of suppressing stickiness of the resulting coating and enhancing the water vapor barrier property and oxygen barrier property, this ratio is 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 be a sucrose fatty acid ester used alone, and therefore the above ratio may be 100% by mass or less.

[0039] (glycerin fatty acid ester) Examples of glycerin fatty acid esters include polyglycerin fatty acid esters such as monoglycerin fatty acid esters, diglycerin fatty acid esters, triglycerin fatty acid esters, etc. In the polyglycerin esters, the average degree of polymerization of the polyglycerin is preferably 2 to 5, and more preferably 2 to 3.

[0040] Monoglycerin fatty acid esters are obtained by an esterification reaction between monoglycerin and fatty acids. Specific examples of fatty acids constituting monoglycerin fatty acid esters include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, 12-hydroxystearic acid, nonadecylic acid, arachidic acid, heneicosylic acid, behenic acid, tricosylic acid, lignocellulose, and the like. Examples of such fatty acids include saturated fatty acids such as noceric acid, cerotic acid, montanic acid, and melissic acid, and unsaturated fatty acids such as α-linolenic acid, stearidonic acid, eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid, linoleic acid, γ-linolenic acid, dihomo-γ-linolenic acid, arachidonic acid, docosapentaenoic acid, palmitoleic acid, vaccenic acid, paulic acid, oleic acid, elaidic acid, erucic acid, nervonic acid, and sapienic acid. Among these, saturated or unsaturated fatty acids having 12 to 20 carbon atoms are preferably used. These fatty acids may be used alone or in combination of two or more.

[0041] Diglycerol fatty acid esters are obtained by an esterification reaction between diglycerol and a fatty acid. Specific examples of the fatty acids constituting the diglycerol fatty acid esters are the same as those listed as examples of the fatty acids constituting the monoglycerol fatty acid esters, and among these, saturated or unsaturated fatty acids having 12 to 20 carbon atoms are preferably used. These fatty acids may be used alone or in combination of two or more.

[0042] Triglycerol fatty acid esters are obtained by an esterification reaction between triglycerol and a fatty acid. Specific examples of the fatty acids constituting the triglycerol fatty acid esters are the same as those listed as examples of the fatty acids constituting the monoglycerol fatty acid esters, and among these, saturated or unsaturated fatty acids having 12 to 20 carbon atoms are preferably used. These fatty acids may be used alone or in combination of two or more.

[0043] (Gas-replacement packaging) There are no particular restrictions on gas replacement packaging as long as it can contain a specific gas. For example, by using a container with a flange and heat-sealing a sealing material, which is a lid material, to the opening, it is possible to create a modified atmosphere package (MAP) that changes the gas atmosphere inside the container. The flange portion is formed so as to surround the opening, and there are no particular restrictions on the width of the flange portion as long as it is a width that allows MAP packaging.

[0044] The material of the container is not particularly limited as long as it can be formed into a predetermined shape, and various materials can be used. For example, polyesters such as PET, polystyrene, and polyolefins such as PE and PP can be used. When used to store fruits and vegetables such as fresh vegetables as a product, it is preferable that consumers can see the fresh vegetables inside the container, and therefore it is preferable to use polyesters such as PET, polystyrene, etc. as materials to impart transparency to the container body.

[0045] In embodiments of the present invention in which fresh produce is housed, it is preferable to encapsulate the ethylene inhibitor 1-methylcyclopropene (1-MCP), which is particularly preferable in greenhouse cultivation where produce is harvested during high temperatures, as it is known that ethylene production is induced by water stress after harvest. Furthermore, the containers do not necessarily have to be plastic containers as described above; for example, when transporting fruits and vegetables from the time they are harvested until they are displayed in a store, they may be packaged in perforated plastic bags or in boxes made of low-moisture-permeable cardboard (moisture-proof cardboard). [Example]

[0046] The present invention will be explained in more detail below based on examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0047] [Test method] (Storage condition 1) The fruits and vegetables were stored at room temperature (20°C) and evaluated according to the following evaluation method. (Storage condition 2) The fruits and vegetables were refrigerated at 0°C, then returned to room temperature (20°C) and stored, and evaluated according to the following evaluation method. (Storage condition 3) The fruits and vegetables were stored at 0°C and evaluated according to the following evaluation method. (Storage condition 4) The fruits and vegetables were stored at 5°C and evaluated according to the following evaluation method. (Storage condition 5) The fruits and vegetables were stored at 10°C and evaluated according to the following evaluation method. (Storage condition 6) The fruits and vegetables were stored at 15°C and evaluated according to the following evaluation method.

[0048] [Evaluation method] Fruits and vegetables (oysters) were preserved under the methods described in the above storage conditions 1 to 6, and then evaluated based on the softening rate after a predetermined number of days. Five samples were prepared for each example, and evaluation was based on the number of softened samples. Softening was judged by the method of Iwata et al. (1969b), when the fruit was close to breaking down when pressed with a finger or when part of the flesh was submerged in water. The reference used was Iwata, Takashi, Nakagawa, Katsuya, and Ogata, Kuniyasu. 1969a. Physiological studies on chilling injury during storage of Natsudaikan fruit (Part 2), Horticultural Science Journal 38:93-100. 1 to 4 are graphs in which the data obtained under storage conditions 1 and 2 are plotted and fitted using a sigmoid function. Fitting to a sigmoid function was performed using the 64-bit solver in Microsoft Excel for Microsoft 365 MSO (version 2308), with the Excel solver set to minimize the residual sum of squares between the non-linear and sigmoid functions. If the fitting results diverged, the sigmoid function coefficients a to c were set while visually checking the shape of the function so that the sigmoid function was close to the measured results. Then, appropriate constraints were set to prevent the coefficients from changing significantly and resulting in fitting to a function with a shape far removed from the set shape.

[0049] [Test Example 1] Aqueous composition 1 was prepared using Mitsubishi Chemical Corporation's "Ryoto (registered trademark) Sugar Ester S-1170" (sucrose stearate, HLB: approximately 11, monoester content: approximately 55% by mass, di- and tri-polyester content: approximately 45% by mass) as a surfactant, with a surfactant / ethanol / water mass ratio of 4 / 5 / 91. The above aqueous composition 1 was applied to the surface of a persimmon by immersion, and dried at 20° C. for 30 minutes to form a coating having a thickness of 1.5 μm. The fruits and vegetables were preserved under the above storage condition 1, and the evaluation results are shown in Table 1 and Figure 1. The fruits and vegetables were preserved under the above storage condition 2, and the evaluation results are shown in Table 1 and Figure 2. Under storage condition 2, the fruits and vegetables were refrigerated at 0°C for 8 weeks, then returned to room temperature (20°C), and the condition after 1 week was evaluated based on the evaluation method below. The coefficients of the sigmoid function obtained by fitting the data under storage conditions 1 and 2 are shown in Table 2. Fitting to the sigmoid function under storage condition 2 was performed starting from 8 weeks (56 days). In addition, in Figures 1 and 2, "SE coating" means that the aqueous composition 1 was applied to the surface of the oyster.

[0050] [Test Example 2] In Test Example 1, evaluation was performed in the same manner as in Test Example 1, except that aqueous composition 1 was not applied. That is, without applying aqueous composition 1 to the surface of oysters, they were preserved under the above-mentioned storage condition 1, and the evaluation results are shown in Table 1 and FIG. 3, the preservation treatment under the above-mentioned storage condition 2, and the evaluation results are shown in Table 1 and FIG. 4, and the preservation treatment under the above-mentioned storage conditions 3 to 6, and the evaluation results are shown in Table 3 and FIG. 5. In storage condition 2, the fruits and vegetables were refrigerated at 0°C for 8 weeks, then returned to room temperature (20°C), and the condition after 1 week was evaluated based on the evaluation method described below. The fitting to the sigmoid function under storage conditions 1 and 2 was performed starting from week 8 (56 days). The coefficients of the sigmoid function obtained at this time are shown in Table 2. In addition, in Figures 3 and 4, "uncoated" means that the aqueous composition 1 was not applied to the surface of the oyster.

[0051] [Table 1]

[0052] [Table 2]

[0053] [Table 3]

[0054] In the following examples, a specific shelf life was set and the optimal storage method for that storage period was calculated using the results of the above Test Examples 1 and 2. Storage conditions 4 to 6 (storage temperature 5 to 15°C) in Test Example 2 were not adopted because softening of the fruit occurred early, and storage conditions were calculated using two types of conditions: storage condition 1 or 2 (20°C, or temperature increase from 0°C to 20°C).

[0055] [Example 1] The optimal storage conditions were calculated for fruits and vegetables that had been applied with aqueous composition 1 and stored under storage condition 1 (20°C), and for fruits and vegetables that had not been applied with aqueous composition 1 and stored under storage condition 2 (refrigerated at 0°C and then returned to 20°C). For storage condition 2, the temperature was changed from 0°C to 20°C on the 7th day. Either storage condition 1 or 2 was selected based on the one that resulted in the least softening rate after 7 days of storage. Under storage condition 1 and storage condition 2, the softening rates were 0% and 7%, respectively, after 7 days of storage, and 1% and 88%, respectively, after 14 days of storage. In other words, since the softening rate was lower under storage condition 1, it was determined that storage at 20°C was the optimal storage condition for fruits and vegetables coated with aqueous composition 1. The results are shown in Table 4 and Figure 6.

[0056] [Table 4]

[0057] [Example 2] The optimum storage conditions were calculated in the same manner as in Example 1, except that the fruits and vegetables to be stored under storage condition 1 (20° C.) were those to which aqueous composition 1 had not been applied. Under storage condition 1 (20°C) and storage condition 2 (refrigerated at 0°C and then returned to 20°C), the softening rates were 1% and 7%, respectively, after 7 days of storage, and 1% and 88%, respectively, after 14 days of storage, with the softening rate being the lowest under storage at 20°C. Therefore, it was determined that storage at 20°C was the optimal storage condition for fruits and vegetables not coated with aqueous composition 1. The results are shown in Table 5 and Figure 7.

[0058] [Table 5]

[0059] [Example 3] The optimal storage conditions were calculated in the same manner as in Example 1, except that the temperature change from 0°C to 20°C in storage condition 2 was set to 70 days, and the condition for selecting either storage condition 1 or 2 was determined based on the one that resulted in the smallest softening rate after 70 days of storage. Under storage condition 1 (20°C) or storage condition 2 (refrigerated at 0°C and then returned to 20°C), the softening rates were 60% and 6%, respectively, after 70 days of storage, and 67% and 33%, respectively, after 73 days of storage.Since the softening rate was lowest when the temperature was changed from 0°C to 20°C, it was determined that changing the temperature from 0°C to 20°C was the optimal storage condition for coated fruits and vegetables.The results are shown in Table 6 and Figure 8.

[0060] [Table 6]

[0061] [Example 4] The optimum storage conditions were calculated in the same manner as in Example 3, except that the fruits and vegetables to be stored under storage condition 1 (20°C) were those to which aqueous composition 1 had not been applied. Under storage condition 1 (20°C) or storage condition 2 (refrigerated at 0°C and then returned to 20°C), the softening rates were 84% and 6%, respectively, after 7 days of storage, and 88% and 33%, respectively, after 73 days of storage.Since the softening rate was lowest when the temperature was changed from 0°C to 20°C, it was determined that changing the temperature from 0°C to 20°C was the optimal storage condition for uncoated fruits and vegetables.The results are shown in Table 7 and Figure 9.

[0062] [Table 7]

[0063] [Example 5] The optimal storage conditions were calculated in the same manner as in Example 3, except that the temperature change from 0°C to 20°C under storage condition 2 was set to 50 days, and the conditions for selecting either storage condition 1 or 2 were as follows: Under storage condition 1 (20°C) and storage condition 2 (refrigerated at 0°C and then returned to 20°C), the softening rates were 17% and 6%, respectively, after 50 days of storage, 21% and 33%, after 53 days of storage, and 27% and 78%, after 56 days of storage. After 50 days of storage, storage condition 2 produced the smallest softening rate, while storage condition 1 produced the smallest softening rate after 53 days of storage. This suggests that the optimal storage conditions vary depending on the circumstances, such as how long it is desirable to suppress softening after changing the storage temperature from 0°C to 20°C. For example, if you want to sell fruits and vegetables within a short period of one to two days, you can select storage condition 2, while if you want to sell them over a period of several days or more, you can select storage condition 1. Here, storage condition 2 was determined to be the optimal storage condition for up to 50 days of storage, and storage condition 1 for fruits and vegetables coated with aqueous composition 1 was determined to be the optimal storage condition for 53 days or more of storage. The results are shown in Table 8 and Figure 10.

[0064] [Table 8]

[0065] [Example 6] The optimum storage conditions were calculated in the same manner as in Example 5, except that the fruits and vegetables to be stored under storage condition 1 (20°C) were those to which aqueous composition 1 had not been applied. Under storage condition 1 (20°C) or storage condition 2 (refrigerated at 0°C and then returned to 20°C), the softening rates were 36% and 6%, respectively, after 50 days of storage, 44% and 33%, after 53 days of storage, and 52% and 78%, after 56 days of storage. Storage condition 2 suppressed the fruit softening rate lower up to 53 days of storage, while storage condition 1 suppressed it lower from 56 days of storage onwards. Based on this, it was determined that storage condition 2 was the optimal storage condition up to 53 days of storage, and that storage condition 1 for fruits and vegetables not coated with aqueous composition 1 was the optimal storage condition from 56 days of storage onwards. The results are shown in Table 9 and FIG. 11.

[0066] [Table 9]

[0067] A comparison of Figures 1 and 3 and Figures 2 and 4 reveals that the maturity relationship for persimmons (kaki) storage methods, regardless of whether they are coated with aqueous composition 1, shows similar trends. That is, storage at 0°C maintains a low softening rate, but returning to 20°C from refrigeration at 0°C rapidly increases the softening rate, with the softening rate reversing by the 9th week. Using these relationships, as shown in Examples 1 to 6, the storage temperature and storage time for refrigerated storage and room temperature storage can be determined depending on the desired storage period. In Examples 1 to 6, the storage conditions are selected by setting the time for returning from refrigeration at 0°C to 20°C. However, the desired number of days for storage may be determined in advance and the time for returning from refrigeration at 0°C to 20°C may be determined accordingly. Furthermore, a comparison between FIG. 1 and FIG. 3 and a comparison between FIG. 2 and FIG. 4 reveals that the softening rate can be reduced by applying the surfactant of the present invention. [Industrial Applicability]

[0068] According to the present invention, conditions such as storage temperature and storage period can be determined according to the desired storage period, so that fruits and vegetables can be displayed in the most optimal condition in stores, etc., and consumers can purchase them in the best condition.

Claims

1. A method for preserving fruits and vegetables in which storage conditions for the fruits and vegetables are determined based on a previously obtained maturity relationship that indicates the relationship between the storage time from harvest until the quality is completely matured (deteriorated) and the maturity.

2. 2. The method for preserving fruits and vegetables according to claim 1, wherein the maturity relationship is obtained by changing at least the holding time from harvest and the storage temperature.

3. 3. The method for preserving fruits and vegetables according to claim 1, wherein the maturity relationship is obtained by varying the holding time at room temperature from harvest, the refrigeration temperature and time, and the holding time at room temperature after refrigeration, and then fitting the results using an S-shaped function.

4. 4. The method for preserving fruits and vegetables according to claim 3, wherein the S-shaped function is any one of a sigmoid function, a Gompertz function, and a Gudermann function.

5. The method for preserving fruits and vegetables according to claim 4, wherein the S-shaped function is a sigmoid function.

6. The method for preserving fruits and vegetables according to claim 1 or 2, wherein at least a storage temperature and a storage period are determined as the storage conditions.

7. 3. The method for preserving fruits and vegetables according to claim 1, wherein the fruits and vegetables are coated with a coating containing a surfactant.

8. The method for preserving fruits and vegetables according to claim 1 or 2, wherein the fruits and vegetables are packaged in a modified atmosphere.

9. The method for preserving fruits and vegetables according to claim 8, wherein the gas contains 1-methylcyclopropene.

10. The method for preserving fruits and vegetables according to claim 1 or 2, wherein the fruits and vegetables are subject to chilling damage.

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