JP7689413B2 - Package containing grapes and method for storing grapes - Google Patents

Description

The present invention relates to a freshness-preserving container for fruits and vegetables, a package containing fruits and vegetables, and a method for storing fruits and vegetables.

A conventional method for preserving the freshness of harvested fruits and vegetables is to moderately suppress the respiration of the fruit and vegetables to maintain their freshness. Packaging bags used to preserve the freshness of such fruits and vegetables are known as modified atmosphere (MA) packaging.

As an example of a freshness preservation method using MA packaging, Patent Document 1 discloses a technology that utilizes a freezing temperature storage method in which fruits and vegetables are stored at 0°C or below, in which grapes are sealed and packaged in a film with an oxygen permeability of 1000 to 10000 cc/ ^m2 ·24 hr·atm at 23°C, and then stored at a low temperature of -3 to 0°C.

Japanese Patent Application Publication No. 6-46749

However, the technology described in Patent Document 1 employs freezing temperature storage at -3 to 0°C, which raises concerns that the grapes may freeze if stored for long periods of time. Furthermore, if the temperature is not frozen, the grapes will breathe more inside the packaging bag, causing humidity inside the bag to rise, which can lead to condensation and mold growth.

It is generally known that the conditions for mold growth depend on various factors such as temperature, humidity, oxygen content, and pH. However, in fruit and vegetables such as grapes, high humidity tends to make them more susceptible to mold growth, while low humidity tends to make them more susceptible to wilting and stem rot. In other words, it has been difficult to simultaneously prevent mold growth and stem rot and wilting.

In addition, a conventional method for preventing mold growth is to sterilize fruits and vegetables with hypochlorite disinfectants beforehand, but such disinfectants require careful handling, and improvements in their use are needed.

As a result of intensive research conducted by the present inventors to solve the problems of the conventional technology, they have come to the new knowledge that it is effective to control the moisture permeability (g/ ^m2 ·day ) at 2°C and 60% RH of the synthetic resin film provided in the freshness-preserving container for fruits and vegetables.
In other words, while it is known that the moisture permeability of synthetic resin films changes depending on temperature and humidity, it has been discovered for the first time that by controlling the moisture permeability within a specific range at 2°C and 60% RH, the storage conditions for fresh produce, it is possible to suppress both the growth of mold and wilting/stalk death, thereby completing the present invention.

The present invention provides a package containing grapes, the package containing grapes being arranged in a freshness-preserving bag for storing fruits and vegetables at normal pressure, the freshness-preserving bag being made of a synthetic resin film,
The synthetic resin film has a moisture permeability (g/ ^m2 ·day ) of 1.9 or more and 2 or less at 2°C and 60% RH, and an oxygen permeability (cc/ ^m2 ·day·atm) of 375 or more and 6500 or less at 23°C and 60% RH,
The synthetic resin film has a multilayer structure including any one of a stretched nylon film, a stretched polylactic acid film, and a stretched polystyrene film,
The grape-containing package is provided, in which a through hole is formed in the fruit and vegetable freshness-preserving bag .

The present invention also provides a method for storing grapes , which comprises storing the grape-containing package at 1° C. to 8° C. under normal pressure .

The present invention provides a freshness-preserving container for fruits and vegetables that can maintain the freshness of the fruits and vegetables while simultaneously preventing mold growth and preventing wilting and stem withering.

<Container for preserving freshness of fruits and vegetables>
Hereinafter, an embodiment of the present invention will be described in detail.

The fruit and vegetable freshness preservation container in this embodiment is for packaging fruit and vegetables inside. The fruit and vegetables are not particularly limited, but may be, for example, Chinese radish, spinach, Japanese mustard spinach, Mizuna, Mibuna, asparagus, Kuusinsai, lettuce, thyme, sage, parsley, Italian parsley, rosemary, oregano, lemon balm, chives, lavender, salad burnet, lamb's ear, rocket, dandelion, nasturtium, basil, arugula, watercress, mulukhiyah, celery, kale, green onion, cabbage, Chinese cabbage, garland chrysanthemum, salad Examples of vegetables that can be used include lettuce, lettuce, butterbur, turnip, bok choy, mitsuba, Japanese parsley, brussels sprouts, broccoli, cauliflower, myoga, radish, carrot, burdock, radish, turnip, sweet potato, potato, Chinese yam, taro, jinenjo, yamatoimo, bell pepper, paprika, shishito, cucumber, eggplant, tomato, cherry tomato, pumpkin, bitter melon, okra, sweet corn, edamame, snow peas, green beans, broad beans, fungi, and mushrooms. Fruits and cut flowers such as citrus fruits, apples, pears, grapes, blueberries, persimmons, and strawberries are also effective. Cut vegetables and fruits are also effective.
Among these, grapes are preferred from the viewpoints of suitability for cold storage and effective inhibition of mold growth.

The moisture permeability of the synthetic resin film provided in the fruit and vegetable freshness-preserving container at 2°C and 60% RH is 0.17 g/ ^m2 ·day or more , preferably 0.5 g/ ^m2 ·day or more , and more preferably 1.0 g/ ^m2 ·day or more , from the viewpoint of suppressing the growth of mold.
On the other hand, the moisture permeability of the synthetic resin film provided in the fruit and vegetable freshness-preserving container at 2°C and 60% RH is 3.3 g/m2· ^day or less , preferably 2.8 g/ ^m2 ·day or less , and more preferably 2.5 g/ ^m2 ·day or less , from the viewpoint of preventing wilting and stem drooping of fruit and vegetables.

In this specification, "wilting/stalk withering" refers to a condition in which dents or wrinkles appear on the surface of fruits or vegetables, or in the case of fruits or vegetables with stems such as grapes, the moisture content of the stem decreases and the stem becomes discolored due to hyperrespiration.

Moisture permeability can be measured using a method conforming to JIS Z0208 (cup method).

In the present invention, the moisture permeability of the synthetic resin film provided in the fruit and vegetable freshness-preserving container at 2°C and 60% RH can be adjusted by controlling the selection of the synthetic resin film material described below, the film manufacturing method, the layer structure of the film, the presence or absence of through holes and the average diameter of the through holes, etc.
Furthermore, by setting the moisture permeability conditions to 2°C and 60% RH, conditions similar to those in which freshness-preserving containers for fruits and vegetables are used and stored are reproduced, which leads to more effective suppression of mold growth and wilting/stalk dieback.

The fruit and vegetable freshness preservation container of the present invention can further enhance the effect of suppressing the occurrence of mold, wilting, and stem withering, as well as the freshness preservation effect, by satisfying the following requirements:

The oxygen permeability of the synthetic resin film provided in the fresh produce freshness-preserving container at 23°C and 60% RH is preferably 2 cc/ ^m2 -day-atm or more, more preferably 5 cc/ ^m2 -day-atm or more, and even more preferably 300 cc/ ^m2 -day-atm or more, from the viewpoint of preserving the respiration of the fresh produce and improving the taste.
On the other hand, the oxygen permeability of the synthetic resin film provided in the fruit and vegetable freshness-preserving container at 23°C and 60% RH is preferably 50,000 cc/ ^m2 -day-atm or less, more preferably 10,000 cc/ ^m2 -day-atm or less, and even more preferably 7,500 cc/ ^m2 -day-atm or less, from the viewpoint of preventing wilting and stalk drooping of fruit and vegetables.

The amount of oxygen permeation can be calculated, for example, by measuring the oxygen concentration inside a packaging container immediately after it is filled with nitrogen and after it has been left for a certain period of time after being filled with nitrogen, and then calculating the oxygen concentration gradient.

In addition, in the present invention, the oxygen transmission rate of the synthetic resin film provided in the fruit and vegetable freshness preservation container at 15°C and 60% RH can be adjusted by controlling the selection of the synthetic resin film material described below, the film manufacturing method, the film layer structure, the presence or absence of through holes, and the average diameter of the through holes.

Furthermore, the fruit and vegetable freshness-preserving container of the present invention may be a bag-shaped container made of the synthetic resin film, or may be a self-supporting container made of the synthetic resin film.
The bag-like container is a flexible bag-like container. It may be capable of standing on its own temporarily by forming it into a predetermined shape, but it is difficult to maintain its shape because it easily changes shape due to stress caused by the shape or movement of the contents or external stress.
The self-supporting container is one that stands on its own when placed at a flat surface, and maintains its shape without application of any particular stress. The self-supporting container may or may not have a lid. The entire container may be made of the synthetic resin film, or the container other than the lid may be made of the synthetic resin film, or the independent storage section and lid section may each be made of the synthetic resin film. From the viewpoint of effectively maintaining the freshness of fruits and vegetables while suppressing the occurrence of mold growth and wilting/stalk withering, it is preferable that the entire container is made of the synthetic resin film.

It is preferable that fruit and vegetable freshness preservation containers are formed with through holes. This allows for stable adjustment of moisture permeability and oxygen transmission. This makes it possible to effectively preserve the freshness of fruit and vegetable while suppressing the growth of mold and the occurrence of wilting and stalk drying.

The planar shape of the through hole may be, for example, a circle, a polygon, or a slit. A circle is not limited to a perfect circle, but includes an approximate circle. In addition to a circle, the hole may be a semicircle or a crescent shape. A polygon may be any shape surrounded by three or more line segments, such as a triangle, a rectangle, or a pentagon. A slit is a cut or narrow gap that penetrates the synthetic resin film that constitutes the fruit and vegetable freshness preservation bag, and may be a straight line, a curve, an L-shape, an X mark, or the like, and its length is not particularly limited.

The average diameter of the through holes is preferably 10 μm to 200 μm. By making the diameter equal to or greater than the lower limit, the moisture permeability and oxygen permeability are improved, and mold growth is easily suppressed. On the other hand, by making the diameter equal to or less than the upper limit, the intrusion of foreign matter is prevented, and the wilting and stem withering of fruits and vegetables can be suppressed.
The average diameter of the through holes is calculated from the open area of the through holes, assuming that the through holes are perfect circles.

The method for forming the through holes is not particularly limited, and any known method can be used. Examples of such known methods include laser processing, needle processing including hot needles, and methods using a mold such as a roll cutter.

The above-mentioned through holes may be formed in the synthetic resin film beforehand when the fruit and vegetable freshness preservation container is manufactured, or may be formed after the synthetic resin film is formed into a bag-like container, or may be formed before or after the synthetic resin film is formed into a bag-like container or a self-supporting container.

The total open area of the fruit and vegetable freshness preservation container per 1 kg of fruit and vegetable is preferably 0.1 ^mm2 /kg or more and 5.4 x ^{102 mm2} /kg or less, and more preferably 0.2 ^mm2 /kg or more and 2.0 x ^{102 mm2} /kg or less. By setting the opening area at or above the lower limit, mold growth can be suppressed and condensation can be suppressed. On the other hand, by setting the opening area at or below the upper limit, the freshness of the fruit and vegetable can be well maintained and the occurrence of wilting and stem withering can be suppressed.
The total opening area does not include the area of the openings for inserting and removing fruits and vegetables from the fruit and vegetable freshness-keeping container.

The inner surface area of the fruit and vegetable freshness-preserving container in this embodiment can be set appropriately depending on the shape, size, handleability, etc. of the fruit and vegetable freshness-preserving container to be packaged. For example, the inner surface area of the fruit and vegetable freshness-preserving container per 100 g of fruit and vegetable may be 100 ^cm2 or more and 5000 ^cm2 or less, or 300 ^cm2 or more and 700 ^cm2 or less.

Next, we will explain the synthetic resin film that is provided in the fruit and vegetable freshness preservation container.

From the viewpoint of allowing the fruit or vegetable to be visually recognized from the outside, the synthetic resin film is preferably transparent or translucent, and more preferably transparent. In addition, the synthetic resin film may be printed with information such as to identify the fruit or vegetable.

The synthetic resin constituting the synthetic resin film is not particularly limited as long as it can be used for packaging fruits and vegetables, and any known synthetic resin can be used.
Examples include various polyethylenes and ethylene copolymers, polypropylene, polyvinyl chloride, polystyrene, acrylic resins, polyester resins such as polyethylene terephthalate and polylactic acid, and polyamide resins such as nylon 6. These may be homopolymers, copolymers of two or more kinds, or blends containing two or more kinds of these homopolymers or copolymers.
Specific examples of the various polyethylenes and ethylene copolymers include ethylene-vinyl alcohol copolymers, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, metallocene-linear low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-propylene copolymer, ethylene-α-olefin copolymer, and other copolymers or ionomers. These may be used alone or in combination of two or more, or may be mixed with other resins.

Among these, from the viewpoint of appropriately controlling moisture permeability and oxygen transmission rate, polyester resins such as polyethylene, ethylene-vinyl alcohol copolymer, polypropylene, polystyrene, and polylactic acid, and polyamide resins such as nylon are preferred, and ethylene-vinyl alcohol copolymer, polystyrene, polylactic acid, and nylon are more preferred.

From the standpoint of cost and physical properties, it is preferable to use heat-sealable anti-fog stretched polypropylene film, low-density polyethylene film, linear low-density polyethylene film, or metallocene-catalyzed polyethylene.

The molding method of the synthetic resin film is not particularly limited, but may be extrusion, inflation, calendering, etc. When molding the synthetic resin film, additives such as an anti-fogging agent may be kneaded, or two or more types of resins may be blended, if necessary.
The synthetic resin film may be stretched or annealed, or may have a sealant layer. In particular, the synthetic resin film may be stretched to improve its rigidity, pinhole resistance, water vapor and oxygen barrier properties, and appearance. For example, stretched nylon, stretched polylactic acid, and stretched polystyrene are preferred.

The synthetic resin film may be used as a single layer or as a multi-layer structure of two or more layers.

For example, when the fruits and vegetables to be packaged in the freshness-preserving container are heavy, it is preferable to use a multi-layer film made of polyethylene by dry lamination, extrusion lamination, or co-extrusion in addition to films such as unstretched polypropylene, oriented polypropylene, unstretched nylon, oriented nylon, and oriented polyester.

The average thickness of the synthetic resin film is preferably 15 μm or more and 2000 μm or less, more preferably 20 μm or more and 1000 μm or less, and even more preferably 25 μm or more and 500 μm or less. By making the thickness equal to or more than the lower limit, it becomes easier to control the oxygen transmission rate and moisture permeability to a higher degree, and the strength of the fruit and vegetable freshness preservation container can be increased. On the other hand, by making the thickness equal to or less than the upper limit, the fruit and vegetable freshness preservation container can be made easier to handle, appropriate moisture permeability and oxygen transmission rate can be imparted, and manufacturing costs can be reduced.

In addition, when the freshness-preserving container for fruits and vegetables is a bag-shaped container, the thickness of the synthetic resin film is preferably 20 μm or more and 40 μm or less. By making the thickness equal to or more than the lower limit, appropriate strength can be obtained. On the other hand, by making the thickness equal to or less than the upper limit, moldability can be improved and manufacturing costs can be reduced.
In addition, when the fruit and vegetable freshness preservation container is made into a self-supporting container, the thickness of the synthetic resin film is preferably 100 μm to 2000 μm. By making the thickness equal to or greater than the lower limit, an appropriate strength can be obtained. On the other hand, by making the thickness equal to or less than the upper limit, it becomes easy to mold the self-supporting container without damaging the through-holes of the synthetic resin film.

Next, a method for producing the fruit and vegetable freshness-keeping container of the present invention will be described.
When the fruit and vegetable freshness-preserving container is a bag-shaped container, a known method can be used for manufacturing the bag-shaped container. Specifically, for example, a synthetic resin film is heat-sealed to form a bag having an opening for inserting and removing fruit and vegetable. In addition, it is preferable to manufacture the bag-shaped container so that two or more through holes do not overlap each other when heat-sealing. This makes it possible to more precisely control the gas permeability of the obtained bag-shaped fruit and vegetable freshness-preserving container.

On the other hand, when the fruit and vegetable freshness preservation container is to be a self-supporting container, the synthetic resin film can be molded into the shape of the container by a known method. For example, vacuum molding, pressure molding, pressure vacuum molding, plug molding, plug-assisted pressure molding, blow molding, etc. are included. In this case, it is preferable to prevent the shape of the through hole from being deformed.
The shape of the self-supporting container can be designed appropriately depending on the fruits and vegetables to be packaged, and examples include a tray shape, a cylindrical shape, a prismatic shape, a hemispherical shape, a spherical shape, a tube shape with a mouth, and a bottle shape with a mouth.

Next, the effects of the fruit and vegetable freshness-keeping container of the present invention will be described.
According to the fruit and vegetable freshness-preserving container of the present invention, the moisture permeability (g/ ^m2 ·day ) of the synthetic resin film at 2°C and 60% RH is set to 0.17 or more and 3.3 or less, which makes it possible to maintain a good environment for preserving the freshness of fruit and vegetable while simultaneously suppressing the growth of mold and the occurrence of wilting and stalk dieback.
In particular, grapes are harvested from summer to autumn, and so it is desirable to be able to store them for a long period of time in order to adjust shipping times. The freshness-keeping container of the present invention makes it possible to store fruits and vegetables such as grapes for a long period of time.

In addition, fruits and vegetables such as grapes are stored in a refrigerator during the period from harvest to shipping, but may be kept at room temperature (15 to 25°C) when they are subsequently displayed in stores. Therefore, even if the freshness of the fruit is maintained in a refrigerator, it may not be maintained after that.
In contrast, the synthetic resin film provided in the fruit and vegetable freshness-preserving container of the present invention combines the above-mentioned specific moisture permeability with an oxygen transmission rate (cc/ ^m2 ·day·atm) of 2 or more and 50,000 or less at 23°C and 60% RH, thereby enabling the freshness of fruit and vegetables to be further preserved even after long-term refrigerated storage and when displayed in stores.

In this way, the fruit and vegetable freshness preservation container of the present invention provides a freshness preservation effect for fruit and vegetable from a perspective not seen before.

<Package containing fruits and vegetables>
The package containing fruits and vegetables in this embodiment is formed by housing fruits and vegetables in the fruit and vegetable freshness-preserving container of this embodiment.

When the fruit and vegetable freshness preservation container is a bag-shaped container, in order to seal the package, a heat sealing treatment may be applied to the opening, or a member such as a back sealing tape, a cable tie, a rubber band, a crimp, etc. Among these, from the viewpoint of enhancing the freshness preservation effect of the fruit and vegetable, it is preferable to apply a heat sealing treatment to the opening.
In addition, when the fruit and vegetable freshness-preserving container is a self-supporting container, it is preferable to seal it with a lid. The lid may be, for example, heat-sealed to seal the self-supporting container.

Fruits and vegetables that have been washed after harvest or that have been wet from rain, snow or dew may be packaged without draining the water. This improves workability. On the other hand, in order to maintain the freshness of fruits and vegetables, they may be stored at low temperatures as soon as possible, or moisture adhering to the fruits and vegetables may be removed by vacuum pre-cooling or the like in order to remove the effects of moisture on the fruits and vegetables as soon as possible.

In addition, the weight retention rate of the package containing fruits and vegetables in this embodiment is preferably 95% or more, more preferably 97% or more, and even more preferably 98% or more. By achieving such a value, the freshness of the fruits and vegetables can be maintained more stably.

<How to store fruits and vegetables>
In the method for storing fruits and vegetables in this embodiment, the fruits and vegetables are stored at 1°C to 8°C while being contained in the above-mentioned fruit and vegetable freshness preservation container. After containing the fruits and vegetables in the fruit and vegetable freshness preservation container, it is preferable to seal it. This makes it possible to stably and highly preserve the freshness of the fruits and vegetables. The storage temperature may be within the range of 1°C to 8°C on average in the environment in which the fruit and vegetable freshness preservation container is stored, and it is also acceptable for the temperature to temporarily fall outside the range of 1°C to 8°C. By keeping the temperature at 1°C to 8°C, freezing of the fruits and vegetables is suppressed, and deterioration of taste and appearance due to freezing can be suppressed. Furthermore, the storage method is not particularly limited, and known methods can be used.

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.
An example of a reference embodiment of the present invention will be described below.
[1]
A freshness-preserving container for fruits and vegetables having a synthetic resin film,
The synthetic resin film has a moisture permeability (g/ ^m2 ·day ) at 2° C. and 60% RH of 0.17 or more and 3.3 or less.
[2]
The fruit and vegetable freshness-preserving container according to [1], having an oxygen transmission rate (cc/ ^m2 ·day·atm) at 23°C and 60% RH of 2 or more and 50,000 or less.
[3]
The fruit and vegetable freshness preservation container according to [1] or [2], wherein a through hole is formed in the fruit and vegetable freshness preservation container.
[4]
The freshness-preserving container for fruits and vegetables according to any one of [1] to [3], wherein the synthetic resin film contains any one of oriented nylon, oriented polylactic acid, oriented polystyrene, and an ethylene-vinyl alcohol copolymer.
[5]
The freshness-preserving container for fruits and vegetables described in any one of [1] to [4], wherein the synthetic resin film has a multi-layer structure.
[6]
The fruit and vegetable freshness-keeping container according to any one of [1] to [5], wherein the total open area of the fruit and vegetable freshness-keeping container per 1 kg of fruit and vegetable is 0.1 mm ² /kg or more and 5.4×10 ² mm ² /kg or less.
[7]
The freshness-keeping container for fruits and vegetables described in any one of [1] to [6] is a bag-shaped container.
[8]
The freshness-keeping container for fruits and vegetables described in any one of [1] to [6] is a self-supporting container.
[9]
The freshness-preserving container for fruits and vegetables described in [8], wherein the self-supporting container comprises a lid portion and a storage portion, and both the lid portion and the storage portion are made of the synthetic resin film.
[10]
The freshness-keeping container for fruits and vegetables described in any one of [1] to [9] is for grapes.
[11]
A package containing fruits and vegetables, the package comprising fruits and vegetables stored in a freshness-preserving container for fruits and vegetables described in any one of [1] to [10].
[12]
The fruit and vegetable package according to [11], wherein the inner surface area of the fruit and vegetable freshness preservation container per 100 g of the fruit or vegetable is 100 ^cm2 or more and 5000 ^cm2 or less.
[13]
A method for storing fruits and vegetables, comprising storing the fruits and vegetables at 1°C to 8°C while keeping them contained in the freshness-preserving container for fruits and vegetables described in any one of [1] to [10].

Next, the present invention will be described in detail using examples, but the content of the present invention is not limited to the examples.

<Production of freshness preservation bags for fruits and vegetables>
Example 1
An ethylene-vinyl alcohol copolymer resin (EVOH: Nippon Synthetic Chemical Industry Co., Ltd., product name: Soarnol 16DX), 1.5 parts by weight of an adhesive material (one-liquid type polybutadiene adhesive Titabond T-180E (Nippon Soda Co., Ltd.)) per 100 parts by weight of the above EVOH, and 7 parts by weight of an anti-fogging material (a mixture of diglycerin laurate and decaglycerin laurate in a ratio of 98:2) per 100 parts by weight of the above EVOH were mixed, and the mixture was applied to a biaxially oriented nylon film (Unitika Ltd., product name "Emblem ONBC", thickness 25 μm) to a thickness of 800 mg/ ^m2 (dry) to form an inner layer film, thereby obtaining a synthetic resin film.
The coating was performed by gravure coating (drying temperature: 100° C., drying time: 10 seconds). The thickness of the inner layer film was 0.8 μm.
The obtained synthetic resin film was perforated with 20 micropores per square ^meter having an average pore size of 125 μm.
Two sheets of this synthetic resin film were stacked together with the inner layer film surface facing on the inside, and heat-sealed on three sides using an impulse sealer (manufactured by Fuji Impulse, FI-400Y-10PK) to form a 10 mm wide heat-sealed area at 160°C for a sealing time of 1 second, to produce a freshness-keeping bag for fruits and vegetables.
The resulting fruit and vegetable freshness-preserving bag had a bag size (inner dimensions) of 300 mm x 400 mm.

Example 2
A freshness-keeping bag for fruits and vegetables was produced using the same synthetic resin film as in Example 1, except that no holes were perforated.

(Comparative Example 1, Reference Example 1)
A synthetic resin film (a biaxially oriented anti-fog polypropylene film (Gunze Co., Ltd., MV2) having a thickness of 25 μm) was perforated with 20 micropores per ^m2 having an average pore size of 120 μm.
Two pieces of the film were stacked together and heat sealed on three sides using an impulse sealer (manufactured by Fuji Impulse, FI-400Y-10PK) to form a 10 mm wide heat sealed area at 140°C for a sealing time of 1 second, to produce a freshness-keeping bag for fruits and vegetables.
The resulting fruit and vegetable freshness-preserving bag had a bag size (inner dimensions) of 300 mm x 400 mm.

(Comparative Example 2)
A commercially available fruit bag for grapes (manufactured by Kobayashi Seitai Sangyo Co., Ltd., product name "Grape 20": inner dimensions 215 mm x 315 mm) was used.

The following measurements were carried out on the resulting fruit and vegetable freshness preservation bags. The results are shown in Table 1.

<Measurement>
Measurement of moisture permeability (g/ ^m2 ·day ) at 2°C and 60% RH Measurement was performed in the same manner as in the moisture permeability test method for moisture-proof packaging materials (cup method) (JIS Z0208), except that the temperature was set to 2°C and the humidity to 60%.

Measurement of oxygen transmission rate (cc/ ^m2 ·day·atm) at 23°C and 60% RH (1) Inclusion of nitrogen gas After sealing the bag with heat seal or the like, the bag was degassed using an aspirator or the like. Degassing was performed until both sides of the bag were stuck together. Next, nitrogen gas (purity 99.9% or more) was filled into the bag using a white hard syringe. The amount of nitrogen gas injected was adjusted to the bag size, and was injected as much as possible within the range where the film constituting the bag was not tensioned by the injected nitrogen gas and was slightly loose, and was measured using the scale of the white hard syringe. The degassing and injection of nitrogen gas were performed, for example, by piercing the bag with a syringe needle. When piercing the syringe needle, double-sided tape was attached to the film constituting the bag, and an adhesive tape made of polypropylene film (hereinafter referred to as "PP tape") was further attached on top of this. In addition, after removing the syringe needle, the needle hole was quickly blocked with PP tape. The tape applied to the bag was limited to an area of 4.5 ^cm2 or less.
Furthermore, when the film constituting the bag was a microporous film, the micropores were not blocked with tape.
(2) Initial oxygen concentration measurement The initial oxygen concentration (C0) in the bag immediately after filling with nitrogen gas (t=0) was measured. The gas in the bag was sampled, and the initial oxygen concentration (C0) in the bag was determined by gas chromatography (TCD). C0 was 0.2% or less, and if it exceeded this, the work was redone. The amount of sampling gas for oxygen concentration measurement was 10 cc or less. When injected into gas chromatography, a fixed amount of about 1 cc was injected. In addition, the same amount of gas was injected to measure standard gas (two or more points including about 1% and about 10% oxygen), and a calibration curve was created.
(3) Storage of the Bag The bag used to measure the initial oxygen concentration was stored at 23°C and 60% RH (in a temperature and humidity chamber). The bag was left stationary so that no objects were placed on it and the air from the fan of the temperature and humidity chamber did not directly hit the bag.
(4) Measurement of oxygen concentration in the bag during storage and calculation of oxygen transmission rate The oxygen concentration in the bag is measured at 3 to 5 points in total, at least 2 points immediately after filling with nitrogen gas and after 3 hours or more have passed, within the range of oxygen concentration of 1% to 7%, and a proportional relationship (correlation coefficient of 0.98 or more) must be established between the elapsed time t (hr) and the oxygen concentration in the bag. If the correlation coefficient does not hold, the test was repeated. If the oxygen transmission rate of the film constituting the bag is too high and the oxygen concentration in the bag increases too quickly and this condition cannot be met, a bag can be created by laminating a part of the film with a smaller oxygen transmission rate than the film being measured and a known film of the same material, and the same procedure can be performed. In this case, the surface area of the bag is excluding the part that is laminated with another known film, and the oxygen transmission rate of the measured film is determined by subtracting the oxygen transmission rate of the known film part from the calculated oxygen transmission rate.
The oxygen transmission rate was calculated using the value for the longer elapsed time according to the following formula (1).
F=1.143×(Ct-C0)×V/t (1)
However, F: oxygen permeation rate (cc/bag/day/atm)
Ct: Oxygen concentration in the bag t hours after filling with nitrogen gas (%)
C0: Oxygen concentration in the bag immediately after filling with nitrogen gas (%)
V: Amount of nitrogen gas filled (cc)
t: time elapsed from gas filling (hr)

Measurement of the average diameter (μm) of through holes The area of the openings on the inner surface of the fruit and vegetable freshness preservation bag was measured for five holes using a microscope (Keyence Corporation, VH-6300). Assuming that the openings are perfect circles, the diameter was calculated from the opening area, and the average diameter was calculated.

Measurement or calculation of the total open area ( ^cm2 ) of the fruit and vegetable freshness-keeping bag First, the total number of perforations was calculated from the area of the fruit and vegetable freshness-keeping bag. The total open area of the fruit and vegetable freshness-keeping bag was calculated using the obtained number of perforations and the average diameter of the above-mentioned through holes.

- Calculation of the inner surface area ( ^cm2 ) of the fruit and vegetable freshness-preserving bag per 100g of fruit and vegetable This was calculated by dividing twice the bag size (inner dimension) ( ^cm2 ) of the fruit and vegetable freshness-preserving bag by the content amount of fruit and vegetable (g)/100.

Weight retention rate of fruit and vegetable packaging:
The weight retention rate before and after storage was measured by the following procedure.
First, the weight (g) (W0) of the bag containing 500 g of grapes was measured on the first day of the test. Next, the weight (g) (W2) after storage for 123 days at 2° C. was measured using an electronic balance. Furthermore, the weight (g) (W3) after storage for 7 days at 15° C. was measured using an electronic balance.
Next, the values calculated from the weights of the obtained bags using the following formulas (2) and (3) were taken as the weight retention rates (%) under the respective storage conditions.
Weight retention rate (%) = (W2/W0) x 100 (2)
Weight retention rate (%) = (W3/W0) x 100 (3)

<Evaluation>
A fruit and vegetable package was produced by sealingly housing about 500 g of grapes inside the obtained fruit and vegetable freshness-keeping bag, and the following evaluations were carried out. Note that, in the evaluation using the fruit and vegetable freshness-keeping bag of Reference Example 1, the grapes were previously treated with hypochlorite.

Evaluation after storage at 2° C.: The fruit and vegetable package was stored at 2° C. for 123 days. After that, grapes were removed from the fruit and vegetable package, and a number of expert panelists evaluated "mold,""withering/drying of stems," and "freshness retention (odor, taste, skin discoloration, spoilage)" on a 10-point scale (10 being the best, with "no mold at all,""no withering/drying of stems at all," and "freshness well retained"), and the average of the total values was calculated and rounded off to the nearest whole number to obtain the results according to the following criteria.
Evaluation after storage at 15° C.: The fruit and vegetable package was stored at 2° C. for 123 days and then further stored at 15° C. for 7 days. After that, grapes were taken out of the fruit and vegetable package and evaluated in the same manner as above by a number of expert panelists.
◎ Rating score: 10 to 9
○ Evaluation score: 7 to 8
△ Rating: 5 to 6
× Rating score: 1 to 4

Claims (5)

A grape-containing package comprising grapes contained in a freshness-preserving bag for storing fruits and vegetables at normal pressure, the freshness-preserving bag being made of a synthetic resin film,
The synthetic resin film has a moisture permeability (g/ ^m2 ·day ) of 1.9 or more and 2 or less at 2°C and 60% RH, and an oxygen permeability (cc/ ^m2 ·day·atm) of 375 or more and 6500 or less at 23°C and 60% RH,
The synthetic resin film has a multilayer structure including any one of a stretched nylon film, a stretched polylactic acid film, and a stretched polystyrene film,
The grape-containing package has a through hole formed in the fruit and vegetable freshness-preserving bag . The grape-containing package according to claim 1, wherein the average diameter of the through holes is 10 μm to 200 μm. The package containing grapes according to claim 1 or 2, wherein the total open area of the fruit or vegetable freshness-preserving bag per 1 kg of fruit or vegetable is 0.1 mm ² /kg or more and 5.4×10 ² mm ² /kg or less. The grape-containing package according to claim 1 , wherein the fruit and vegetable freshness-preserving bag has an inner surface area of 100 cm ² or more and 5,000 cm ² or less per 100 g of grapes. A method for storing grapes, comprising storing the package containing grapes according to any one of claims 1 to 4 at 1°C to 8°C under normal pressure.