JP2024073812A - Freshness-preserving bag, packaging body, and freshness-preserving method - Google Patents

Abstract

The present invention provides a technology that can effectively preserve the freshness of fruits and vegetables.
The freshness-preserving bag 100 of the present invention has an oxygen transmission rate of 80 to 1000 cc/day·atm, as measured by the following procedure.
(Procedure) Nitrogen gas is filled into the freshness preservation bag, sealed, and left at 20°C and 80% RH for a certain period of time. The oxygen concentration (volume %) in the freshness preservation bag immediately after filling with nitrogen gas and the oxygen concentration (volume %) in the freshness preservation bag t days after filling with nitrogen gas are measured, and the oxygen transmission rate [cc/day·atm] is calculated using formula (1). Formula (1): Oxygen transmission rate [cc/day·atm]={(Ct-C0)/k}×V÷t (where, in formula (1), Ct: oxygen concentration (volume %) in the freshness preservation bag t days after filling with nitrogen gas, C0: oxygen concentration (volume %) in the freshness preservation bag immediately after filling with nitrogen, V: amount of nitrogen gas filled (cc), t: time elapsed from gas filling (days), k: concentration correction coefficient (21 considering the oxygen concentration in the atmosphere).)
[Selected Figure] Figure 1

Description

The present invention relates to a freshness preservation bag, a package, and a freshness preservation method.

Vegetables, fruits, and other fresh produce continue to respire even after they have been harvested. As a result, during storage, distribution, or preservation after harvest, the fresh produce consumes energy through their own respiration, causing a deterioration in freshness. As a method for preserving the freshness of fresh produce, a method that appropriately suppresses the respiration of the fruit and vegetable to maintain the freshness is known. Packaging bags used to maintain the freshness of such fruit and vegetable are known as MA (Modified Atmosphere) packaging.

For example, Patent Document 1 discloses that the oxygen permeability, water vapor permeability, and tensile modulus of a synthetic resin film used in a freshness-preserving storage bag for fruits and vegetables are specified. Patent Document 2 discloses a packaging method for packaging fruits and vegetables using a film with oxygen permeability and holes with a diameter of 10 μm or less.

JP 2019-64720 A JP 2017-153455 A

However, the conventional technologies described in Patent Documents 1 and 2 focus on the oxygen permeability of the resin film that constitutes the packaging bag, and there is room for improvement in terms of maintaining a high level of freshness of fruits and vegetables.

The inventors conducted research focusing on packaging bags with connecting passages in the back of the bags that allow gas and water vapor to pass through, and discovered that the freshness of fruits and vegetables can be improved more effectively by controlling the amount of oxygen that passes through the entire packaging bag, measured using a specified procedure, rather than by controlling the oxygen permeability of the resin film that makes up the packaging bag.

In other words, the present invention provides the following technology related to freshness-preserving bags:

[1] A freshness-keeping bag comprising a bag body for containing fruits and vegetables obtained by bonding both ends of a synthetic resin film together to form a cylindrical shape and closing one end thereof, and a back-pasted portion,
The back lining portion has a communication area that communicates the outside and the inside of the bag body,
The freshness preservation bag has an oxygen permeability of 80 to 1000 cc/day·atm as measured by the following procedure.
(Procedure) The freshness preservation bag is filled with nitrogen gas, sealed, and left for a certain period of time under conditions of 20° C. and 80% RH. The oxygen concentration (volume %) in the freshness preservation bag immediately after filling with the nitrogen gas and the oxygen concentration (volume %) in the freshness preservation bag t days after filling with the nitrogen gas are measured, and the oxygen transmission rate [cc/day·atm] is calculated from the following formula (1).
Formula (1): Oxygen permeability [cc/day·atm]={(Ct−C0)/k}×V÷t
However, in formula (1),
Ct: Oxygen concentration (volume%) in the freshness preservation bag t days after filling with nitrogen gas
C0: Oxygen concentration (volume%) in the freshness-preserving bag immediately after filling with nitrogen
V: Amount of nitrogen gas filled (cc)
t: time elapsed since gas filling (days)
k: concentration correction coefficient (set to 21 in consideration of the oxygen concentration in the atmosphere)
respectively.
[2] In the freshness-preserving bag according to [1],
The freshness-preserving bag has an oxygen transmission rate of 3 to 30 ([cc/day·atm]/cm) per length (cm) of the back-pasted portion.
[3] In the freshness-preserving bag according to [1] or [2],
The freshness-preserving bag has a width of 2 to 50 mm.
[4] In the freshness-preserving bag according to any one of [1] to [3],
The freshness-keeping bag has a plurality of communicating regions, and the number of the communicating regions is 0.50 to 250 per 10 ^cm2 area in a plan view of the back adhesive portion.
[5] In the freshness-preserving bag according to any one of [1] to [4],
The freshness-keeping bag has a distance between adjacent communicating regions at an end of the back-pasted portion on the bag body side of 1.0 to 300 mm.
[6] In the freshness-preserving bag according to any one of [1] to [5],
The freshness-keeping bag has a geometric pattern formed by alternately arranging the communicating regions and the joining regions in the longitudinal direction of the backing portion.
[7] In the freshness-preserving bag according to [6],
The freshness-keeping bag has a geometric pattern whose pattern constituent units include one or more shapes selected from a straight line, a rectangle, a circle, and a curve.
[8] In the freshness-preserving bag according to any one of [1] to [7],
The freshness-keeping bag has a strip-shaped non-sealed portion extending from the upper end to the lower end of the back-attached portion on the side opposite the bag body.
[9] In the freshness-preserving bag according to [8],
The freshness-keeping bag has a width of 1 to 40 mm in the band-shaped non-sealed portion.
[10] In the freshness-preserving bag according to any one of [1] to [9],
The freshness-preserving bag, wherein the thickness of the synthetic resin film is 20 to 200 μm.
[11] In the freshness-preserving bag according to any one of [1] to [10],
The synthetic resin film is a film containing one or more selected from polyethylene, ethylene copolymer, polypropylene, polyvinyl chloride, polystyrene, acrylic resin, polyester resin, and polyamide resin, or a multilayer film containing the film.
[12] A package comprising fruits and vegetables housed in the freshness-preserving bag body according to any one of [1] to [11].
[13] A freshness preservation method comprising storing fruits and vegetables in a bag body of the freshness preservation bag described in any one of [1] to [11] and preserving the fruits and vegetables.

The present invention provides a technology that can effectively preserve the freshness of fruits and vegetables.

1 is a perspective view showing a schematic view of a freshness-preserving packaging bag according to an embodiment of the present invention. 1 is a perspective view showing a schematic diagram of a modified example of the freshness-preserving packaging bag of the present embodiment. FIG. 1 is a perspective view showing a manufacturing procedure of the freshness-preserving packaging bag of the present embodiment. FIG.

In this specification, the expression "a to b" in the description of a numerical range means from a to b, unless otherwise specified. For example, "1 to 5 mass%" means "1 mass% to 5 mass%." Furthermore, the lower limit and upper limit of a numerical range can be arbitrarily combined with the lower limit and upper limit of another numerical range.
Unless otherwise specified, each of the components and materials exemplified in this specification may be used alone or in combination of two or more kinds.

In this specification, when the length direction of the back adhesive part of the freshness-preserving bag is parallel to the direction of gravity, "upper" refers to the direction in which the opening of the freshness-preserving bag is located, and "lower" refers to the side opposite the opening of the freshness-preserving bag, i.e., the direction in which the bottom of the freshness-preserving bag is located.
In this specification, the freshness-preserving bag will also be referred to as a packaging bag.

The following describes an embodiment of the present invention.

<Freshness preservation bag>
FIG. 1 is a schematic perspective view showing one aspect of a freshness-preserving bag 100 according to the present embodiment.
As shown in Figure 1, the freshness-preserving bag 100 comprises a bag body 10 for containing fruits and vegetables, which is obtained by bonding both ends of a synthetic resin film together to form a tube and closing one opening, a back panel 20, and an opening at the top for putting fruits and vegetables in and taking them out.
The bag body 10 has a seal portion 11 at its lower end, which forms the bottom of the bag.
The back-attached portion 20 is formed by bonding both ends of a synthetic resin film together, and has an end 21 that is joined to the bag body 10 and an end 22 that is opposite the bag body 10, and is provided with a seal portion 25 at the lower end. In this embodiment, the back-attached portion 20 has a communication region 30 that communicates between the outside and the inside of the bag body 10.

The freshness preservation bag 100 of this embodiment has an oxygen transmission rate of 80 to 1000 cc/day·atm, as measured by the following procedure.
(Procedure) Nitrogen gas is filled into freshness preservation bag 100, which is then sealed and left for a certain period of time under conditions of 20° C. and 80% RH. The oxygen concentration (volume %) in freshness preservation bag 100 immediately after filling with the nitrogen gas and the oxygen concentration (volume %) in freshness preservation bag 100 t days after filling with the nitrogen gas are measured, and the oxygen transmission rate [cc/day·atm] is calculated from the following formula (1).
Formula (1): Oxygen permeability [cc/day·atm]={(Ct−C0)/k}×V÷t
However, in formula (1),
Ct: Oxygen concentration (volume%) in the freshness preservation bag 100 t days after filling with nitrogen gas
C0: Oxygen concentration (volume%) in the freshness preservation bag 100 immediately after filling with nitrogen
V: Amount of nitrogen gas filled (cc)
t: time elapsed since gas filling (days)
k: concentration correction coefficient (set to 21 in consideration of the oxygen concentration in the atmosphere)
respectively.

In the above procedure, the oxygen concentration can be measured by sampling the gas in the freshness preservation bag 100 and using a portable gas concentration meter Check Point 3 (manufactured by MOCON Europe). The operation is performed in the atmosphere.
After the initial oxygen concentration is measured, the freshness preservation bag 100 is moved to a constant temperature and humidity cabinet controlled at 20° C. and 80% RH for storage. At this time, the freshness preservation bag 100 is placed undisturbed so that no objects are placed on it and the bag is not directly exposed to the wind from the fan of the constant temperature and humidity cabinet.
In order to properly measure the amount of oxygen transmitted, it is preferable that the internal surface area of freshness preservation bag 100 is 0.06 ^m2 or more.

The oxygen transmission rate in the freshness preservation bag 100 is measured as follows. In addition, since the oxygen transmission rate can be measured under appropriate conditions by adjusting the measurement time (t), multiple samples are prepared and the average value of the samples measured under appropriate conditions is used.
Measurement of C0: Immediately after filling the freshness preservation bag 100 with V (cc) of nitrogen gas, the oxygen concentration (C0) is measured. C0 is 0.2% by volume or less, and if it exceeds this, the measurement process is to be repeated.
Measurement of Ct: The oxygen concentration (Ct) after t days is measured 3 hours or more after filling with nitrogen gas. The oxygen concentration inside the bag is measured for multiple freshness preservation bags 100 at a predetermined timing. Only freshness preservation bags 100 whose oxygen concentration (Ct) after t days is 1% by volume or more and 7% by volume or less are adopted. On the other hand, for freshness preservation bags 100 that do not show a value of 1% by volume or more and 7% by volume or less, t is shortened, and the measurement is repeated until a value of 1% by volume or more and 7% by volume or less is obtained.
Furthermore, since a proportional relationship (correlation coefficient of 0.98 or more) must be established between the time t days after filling with nitrogen gas and the oxygen concentration (Ct) inside the freshness-preserving bag 100, if the correlation coefficient does not hold, t will be shortened and the measurement process will be repeated until a proportional relationship is established.
The obtained V, C0, and Ct values can be substituted into the above formula (1) to calculate the oxygen transmission rate [cc/day·atm].

The oxygen permeability is 80 to 1000 cc/day·atm, preferably 90 to 990 cc/day·atm.

The oxygen permeability of the freshness-preserving bag 100 of this embodiment can be controlled, for example, by the selection of the synthetic resin film material, the presence or absence and shape of the through holes and communication areas 30, etc.

In other words, the freshness preservation bag 100 of this embodiment can control the oxygen permeability more precisely and stably by specifying the oxygen permeability of the entire freshness preservation bag 100, rather than the oxygen permeability of the synthetic resin form itself, and can stably obtain the freshness preservation effect.

In addition, the freshness preservation bag 100 of this embodiment has a communication area 30 in the back lining 20, so that the freshness preservation effect can be obtained more stably. Specifically, for example, even if the end of the freshness preservation bag 100 is crushed or the package containing the fruit and vegetables is twisted, the back lining 20 is located approximately in the center of the freshness preservation bag 100, so it is less susceptible to the effects of such crushing or twisting, and the permeability of the communication area 30 can be easily maintained. As a result, it is presumed that the respiration of the fruit and vegetables can be stably restricted, and the freshness preservation effect can be stably obtained.

In this embodiment, the oxygen transmission rate per unit length (cm) of backing 20 is preferably 1.0 to 30 ([cc/day·atm]/cm), and more preferably 1.5 to 25 ([cc/day·atm]/cm). This allows the oxygen concentration in freshness-preserving bag 100 to be easily controlled at a higher level.
The length (cm) of the backing portion 20 corresponds to the vertical length (cm) of the freshness preservation bag 100 .

Other configurations of the freshness preservation bag 100 of this embodiment are described below.

[Synthetic resin film]
The freshness preservation bag 100 of the present embodiment is made of a synthetic resin film. This allows fruits and vegetables to breathe appropriately while obtaining the MA effect. It also suppresses odors, making it easier to maintain a good appearance of the fruits and vegetables.

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 for the purpose of identifying the fruit or vegetable, etc.

The 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 resin can be used.
For example, the synthetic resin film is preferably one or more selected from the group consisting of polyethylene, ethylene-based copolymers such as ethylene-vinyl alcohol copolymers, polypropylene, polyvinyl chloride, polystyrene, (meth)acrylic resins, polyester resins such as polylactic acid, and polyamide resins such as nylon.
Among these, polyethylene, ethylene-vinyl alcohol copolymer, polypropylene, polylactic acid, and nylon are preferred from the viewpoint of appropriately controlling the water vapor permeability and oxygen permeability described below.

The method for forming the synthetic resin film is not particularly limited, but may be extrusion, inflation, calendaring, etc. When forming the resin film, additives such as an anti-fogging agent may be kneaded, if necessary, or one or more types of resins may be blended.
The synthetic resin film may be subjected to a stretching treatment or annealing, and may further be provided with a sealant layer to impart heat sealability.

The thickness of the synthetic resin film is preferably 20 to 200 μm, more preferably 20 to 100 μm, and even more preferably 20 to 50 μm.

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

[Back attachment portion 20]
In this embodiment, the back-attached portion 20 is a sealed area obtained by attaching both ends of the synthetic resin film. The back-attached portion 20 is formed so as to protrude from the bag body 10 across both bonded ends. That is, the back-attached portion 20 protrudes from the upper end to the lower end of the freshness-preserving bag 100. The protruding back-attached portion 20 may be used in a manner in which it falls along the bag body 10 and covers the bag body 10.

The width of the back-pasted portion 20 is adjusted appropriately according to the size of the freshness-preserving bag 100, but is preferably 2 to 700 mm, more preferably 5 to 650 mm, even more preferably 10 to 600 mm, and even more preferably 20 to 500 mm. By making the width of the back-pasted portion 20 equal to or greater than the above-mentioned lower limit, the seal strength for maintaining the shape of the freshness-preserving bag 100 can be improved while still providing the communication region 30. By making the width of the back-pasted portion 20 equal to or less than the above-mentioned upper limit, the freshness-preserving effect can be more easily maintained.

As shown in FIG. 1, the back adhesive portion 20 has a joint region 31 and a communicating region 31 consisting of a non-joint region. In this embodiment, the joint region 31 is provided from the end 21 to the end 22 of the back adhesive portion 20.

However, the joining area 31 is not limited to being provided from the end 21 to the end 22 of the back bonding portion 20 .
For example, as shown in FIG. 2 , back panel 20 may have a strip-shaped non-sealed portion 35 at end 22 opposite bag body 10 that extends from the top end to the bottom end of freshness-preserving bag 100 .
The band-shaped non-sealed portion 35 corresponds to an end of the synthetic resin film that is not bonded when the ends of the synthetic resin film are bonded together to form a cylindrical shape. In addition, the lower end of the non-sealed portion 35 may be bonded to form the sealed portion 25.
The width of the band-shaped non-sealed portion 35 is preferably 1 to 20 mm, and more preferably 3 to 10 mm.
By satisfying the above conditions, the freshness preservation effect can be obtained also in freshness preservation bag 101. In this case, it is preferable to cut non-sealed area 35 in advance and leave the end of communication area 30 exposed.

[Communication region 30]
The communication area 30 in this embodiment is provided in the back bonding portion 20 and is an area that allows communication between the bag body 10 and the outside. This controls the amount of oxygen gas, carbon dioxide gas, and water vapor that enters and leaves the bag body 10, making it easier to maintain the freshness of fruits and vegetables. The communication area 30 can be formed by providing a non-bonded area when bonding the back bonding portion 20.
Specific examples of the communication region 30 include the following.

In this embodiment, the communication region 30 is provided from the end 21 to the end 22 of the back adhesive portion 20 and forms a single flow path.
When the communication region 30 is a single flow path, the length of the path is preferably 10 to 50 mm, more preferably 15 to 45 mm, and even more preferably 20 to 40 mm.
The path length is the average length when tracing the center of the communication region 30.

However, the communication region 30 is not limited to being connected by a single flow path, and may be a branched flow path.
When the communication region 30 is a branched flow path, the length of the path is intended to be the shortest path, and is preferably 10 to 50 mm, more preferably 15 to 45 mm, and even more preferably 20 to 40 mm.

As shown in FIG. 1 , the communication region 30 in this embodiment is a non-linear, S-shaped single flow path that is wider from the end 21 to the end 22 .
That is, the communication region 30 of this embodiment is a flow path of non-uniform width from one end 21 to the other end 22 of the back adhesive portion 20 in a plan view.
The average width of the communication region 30 is preferably 0.2 to 7 mm, and more preferably 0.3 to 6 mm.

However, the communicating flow passage 20 is not limited to being non-linear, and may be linear, non-linear, or a combination thereof. The width of the communicating region 30 may be a uniform width, or parallel linear or non-linear flow passages.
For example, the communication region 31 may be a single linear flow path that widens in width from the end 21 to the end 22 .

As shown in FIG. 1, two communication regions 30 are provided in the back lining 20 in this embodiment. The communication regions 30 are preferably provided at equal intervals, and the interval (pitch P) is preferably 1 to 300 mm, more preferably 2 to 250 mm, and even more preferably 3 to 100 mm, at the joining edge of the back lining 20 with the bag body 10 (end 21 of the back lining 20).

However, the number of communicating regions 30 is not limited to this. It is preferable that there are a plurality of communicating regions 30, and the number of communicating regions 30 in the back lining portion 20 may be 3 to 200, or may be 50 to 100.
In this case, the number of the multiple communication regions 30 is preferably 0.5 to 250 per 10 cm ² area of the back bonding portion 20 in a plan view, more preferably 1 to 200, and even more preferably 10 to 150.

As shown in FIG. 1, the communication region 30 of this embodiment has flow paths of the same shape, size, and length arranged repeatedly.

However, the shapes, sizes, lengths, etc. of the multiple communicating regions 30 may be different from one another, and multiple communicating regions may be combined to form one repeating unit.
In this case, the number of at least one repeating unit is preferably 0.5 to 250, more preferably 1 to 200, and even more preferably 10 to 150 per 10 cm ² area of the backing portion 20 in a plan view.
Furthermore, it is preferable that at least one repeating unit is arranged at equal intervals, and the interval (pitch P) at the joining edge (end 21 of the back bonding portion 20) with the bag body 10 is preferably 1 to 300 mm, more preferably 2 to 200 mm, and even more preferably 3 to 100 mm.

In addition, the plurality of communication regions 30 may be arranged alternately with the joint regions 31 to form a geometric pattern in the back adhesive portion 20. That is, the joint regions 31 and the communication regions 30 are regularly arranged in the longitudinal direction of the back adhesive portion 20.
The pattern constituent units of the geometric pattern include one or more selected from straight lines, rectangles, circles, and curves.

(Formation method)
The communication region 30 may be formed, for example, by overlapping both ends of a synthetic resin film so that the surfaces that will become the insides of the bag body 10 face each other as shown in Fig. 3(a), and then bonding the area other than the communication region 30 as shown in Fig. 3(b). Examples of the bonding method include known methods such as thermal fusion by heating and ultrasonic fusion.

[Bag body 10]
In this embodiment, the bag body 10 is a bag for storing fresh produce obtained by forming a cylindrical shape by bonding both ends of the above-mentioned synthetic resin film and forming a bottom with a sealing portion 11, such as by bonding one end of the cylindrical shape, and this is the area excluding the back sealing portion 20 of the freshness-preserving bag 100.

From the viewpoint of preserving the respiration of fruits and vegetables and preserving their freshness, the oxygen permeability of the synthetic resin film at 23°C and 60% RH is preferably 200 cc/( ^m2 ·day·atm) or more, more preferably 500 cc/( ^m2 ·day·atm) or more, even more preferably 800 cc/( ^m2 ·day·atm) or more, and particularly preferably 1000 cc/( ^m2 ·day·atm) or more.
On the other hand, from the viewpoint of preserving the quality and freshness of fruits and vegetables, the oxygen permeability of the synthetic resin film at 23°C and 60% RH is preferably 10,000 cc/( ^m2 ·day·atm) or less, more preferably 7,000 cc/( ^m2 ·day·atm) or less, even more preferably 4,000 cc/( ^m2 ·day·atm) or less, and particularly preferably 3,000 cc/( ^m2 ·day·atm) or less.

The water vapor permeability of the synthetic resin film at 40° C. is preferably 1 g/(m ² ·day) or more, and more preferably 3 g/(m ² ·day) or more, from the viewpoint of releasing water vapor due to respiration of fruits and vegetables.
On the other hand, from the viewpoint of suppressing respiration of fruits and vegetables, the water vapor permeability of the synthetic resin film at 40°C is preferably 300 g/( ^m2 ·day) or less, more preferably 100 g/( ^m2 ·day) or less, even more preferably 50 g/( ^m2 ·day) or less, and particularly preferably 10 g/( ^m2 ·day) or less.

Water vapor permeability can be measured using a method conforming to JIS Z 0208 (cup method).

In addition, in this embodiment, the oxygen permeability and water vapor permeability of the synthetic resin film constituting the bag body 10 are intended to be the oxygen permeability and water vapor permeability of the bag body 10 that does not include the above-mentioned communication region 30. In this case, they can be adjusted by controlling the selection of the material of the synthetic resin film, the manufacturing method of the synthetic resin film, the layer structure of the synthetic resin film, etc.

The bag body 10 of this embodiment may have a through hole formed therein, but may not have a through hole. Depending on the presence or absence of a through hole, the water vapor permeability and oxygen permeability of the freshness preservation bag 100 can be further adjusted.

The planar shape of the through hole may be, for example, a circle, a polygon, or a slit. A slit is a cut or narrow gap that penetrates the synthetic resin sheet that constitutes the packaging material, and may be a straight line, a curve, an L-shape, an X mark, etc., and there is no particular limit to the length, etc.

The average diameter of the through holes is preferably 10 μm to 800 μm, more preferably 20 μm to 500 μm, and even more preferably 50 μm to 200 μm. In this case, the average diameter of the through holes is calculated from the opening area of the through holes, assuming that the through holes are perfect circles.

The through holes can be provided at least either before or after the synthetic resin film is made into a bag shape.

<Packaging>
The package of the present embodiment contains fruits and vegetables in the above-mentioned freshness preservation bag 100. The package is preferably one in which the opening of the freshness preservation bag 100 is sealed.
The above sealing may be achieved, for example, by subjecting the opening of the bag to a heat sealing process, or by using a member such as back sealing tape, a cable tie, a rubber band, or a crimp.

In this embodiment, the inner surface area of the packaging body per 100 g of fruit or vegetable is preferably 100 to 5000 ^cm2 , more preferably 200 to 1000 ^cm2 , even more preferably 250 to 800 ^cm2 , and particularly preferably 300 to 600 ^cm2 .

In this embodiment, the package is preferably stored at an environmental temperature of 2 to 25°C. However, the temperature may change depending on the application, distribution conditions, etc.

[Fruits and vegetables]
The packaging body of this embodiment contains fruits and vegetables in a freshness-preserving bag 100 .
Examples of fruits and vegetables include, but are not limited to, oba, spinach, komatsuna, mizuna, mibuna, Chinese chives, asparagus, swiss cabbage, lettuce, thyme, sage, parsley, Italian parsley, rosemary, oregano, cilantro, lemon balm, chives, lavender, salad burnet, lamb's ear, rocket, dandelion, nasturtium, basil, arugula, watercress, mulukhiyah, celery, kale, green onion, cabbage, Chinese cabbage, and chrysanthemum. Lettuce, lettuce, butterbur, turnip, bok choy, mitsuba, 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 are also effective. Fruits such as citrus fruits, apples, pears, grapes, blueberries, persimmons, and strawberries, as well as cut flowers, are also effective. Cut vegetables and fruits are also effective.
Cut vegetables refer to uncooked vegetables that have been harvested in the fields and have had inedible parts, such as roots, stems, or flowers, removed, and that have been cut in a known manner to make them easier to eat and to improve their appearance.

<How to maintain freshness>
The freshness preservation method of the present embodiment is a method for preserving the freshness of fruits and vegetables by storing the fruits and vegetables in the above-described freshness preservation bag 100. After storing the fruits and vegetables, it is preferable that the opening of freshness preservation bag 100 is sealed.

The above describes embodiments of the present invention, but these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

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

<Measurement>
1. Measurement of oxygen transmission rate of freshness preservation bag Nitrogen gas was filled into a freshness preservation bag, sealed, and left for a certain period of time. The oxygen concentration (volume %) in the freshness preservation bag immediately after filling with nitrogen gas and the oxygen concentration (volume %) in the freshness preservation bag t days after filling with nitrogen gas were measured, and the oxygen transmission rate [cc/day·atm] was calculated from the following formula (1).
The gas concentration was measured using a portable gas concentration meter Check Point 3 (manufactured by MOCON Europe).

Formula (1): Oxygen permeability [cc/day·atm]={(Ct−C0)/k}×V÷t
However, in formula (1),
Ct: Oxygen concentration (volume%) in the freshness preservation bag t days after filling with nitrogen gas
C0: Oxygen concentration (volume%) in the freshness-preserving bag immediately after filling with nitrogen
V: Amount of nitrogen gas filled (cc)
t: time elapsed since gas filling (days)
k: concentration correction coefficient (set to 21 in consideration of the oxygen concentration in the atmosphere)

More specifically, the procedure was as follows.
(1) The opening of the freshness preservation bag was sealed using an impulse sealer (manufactured by Fuji Impulse, FI-400Y-10PK), and then degassing was performed using an aspirator until both sides of the packaging bag were stuck together. Next, the freshness preservation bag was filled with nitrogen gas (purity 99.9% or more) using a white hard syringe. The amount of nitrogen gas filled V (cc) was measured using the scale on the syringe, with as much gas as possible being poured in without applying tension to the freshness preservation bag.
(2) The gas was degassed and injected by piercing the body of the freshness-preserving bag with an injection needle. When inserting the needle, double-sided tape was applied to the film, and then a polypropylene film adhesive tape (hereinafter referred to as "PP tape") was applied on top of the tape. After the needle was removed, the pinhole was quickly blocked with PP tape. The tape applied to the bag was made to fit within an area of ^4.5 cm2 or less. However, if a through hole was provided in the bag body, it was not blocked with PP tape.
(3) Measurement of initial oxygen concentration (C0) First, the oxygen concentration (C0) in the freshness preservation bag 100 was measured immediately after filling it with V (cc) of nitrogen gas. C0 was 0.2% by volume or less, and if it exceeded this, the measurement was repeated.
(4) Storage of bags Next, the bags whose initial oxygen concentrations had been measured were stored in a temperature and humidity chamber in which the conditions inside the chamber were controlled to 20° C. and 80% RH. At this time, the bags were left undisturbed so that no objects were placed on top of them and they were not directly exposed to the wind from the temperature and humidity chamber fan.
(5) Measurement of oxygen concentration (Ct) in the bag during storage and calculation of oxygen transmission rate Next, after 3 hours or more had passed since filling with nitrogen gas, the oxygen concentration (Ct) in the bag was measured at a total of two or more points at specified timings.
Specifically, the oxygen concentration (Ct) after t days was measured 3 hours or more after filling with nitrogen gas. The oxygen concentration inside the bag was measured for multiple freshness preservation bags 100 at a predetermined timing. Among them, only freshness preservation bags 100 whose oxygen concentration (Ct) after t days was 1 vol% or more and 7 vol% or less were adopted. On the other hand, for freshness preservation bags 100 that did not show a value of 1 vol% or more and 7 vol% or less, t was shortened and the measurement was repeated until a value of 1 vol% or more and 7 vol% or less was obtained.
Furthermore, since a proportional relationship (correlation coefficient of 0.98 or more) must be established between the time t days after filling with nitrogen gas and the oxygen concentration (Ct) inside the freshness-preserving bag 100, if the correlation coefficient was not established, t was shortened and the measurement was repeated until the proportional relationship was established.

<Examples and Comparative Examples>
(1) Preparation of freshness-preserving bag To obtain the freshness-preserving bag shown in Table 1, a bag having a back-pasted portion with a communicating region was prepared using a synthetic resin film by a known method.
The following raw materials were used:
OPP: biaxially oriented polypropylene film PE: polyethylene film PET: polyethylene terephthalate film In Example 7 and Comparative Example 2, a synthetic resin film was prepared by laminating PE (40 μm) onto a nylon film (15 μm), and bags were made with the PE on the inside.
In Example 9, a synthetic resin film was prepared by laminating a polyethylene terephthalate film (12 μm) with PE (40 μm), and a bag was produced with the PE facing inside.

(2) Evaluation of freshness-retaining effect Fruits and vegetables shown in Table 1 were placed in the obtained freshness-retaining bag, and the opening was heat-sealed to close, to obtain a package containing fruits and vegetables. The obtained package was turned upside down every day and stored under the conditions shown in Table 1, and then the freshness-retaining effect was evaluated according to the following evaluation criteria, using the fresh state (initial state) before storage as the standard.

・Evaluation criteria <Odor>
◎: No difference from the initial state 〇: A slight strange odor is detected, but the smell of fruits and vegetables is stronger △: The strange odor is stronger than the smell of fruits and vegetables ×: A strong strange odor <Appearance (fruits and vegetables)>
◎: No difference from the initial stage 〇: Discolored by about 10% compared to the initial stage △: Discolored by about 30% compared to the initial stage ×: Discolored by more than 50% compared to the initial stage <Taste>
◎: No difference from the initial state. 〇: The taste is slightly diluted, but the original taste of the fruit and vegetables is still there. △: The original taste of the fruit and vegetables has been clearly diluted. ×: Unpalatable.

Claims (13)

A freshness-preserving bag comprising a bag body for containing fruits and vegetables, the bag body being obtained by bonding both ends of a synthetic resin film together to form a cylindrical shape and closing one end thereof, and a back-pasted portion,
The back lining portion has a communication area that communicates the outside and the inside of the bag body,
The freshness preservation bag has an oxygen permeability of 80 to 1000 cc/day·atm as measured by the following procedure.
(Procedure) The freshness preservation bag is filled with nitrogen gas, sealed, and left for a certain period of time under conditions of 20° C. and 80% RH. The oxygen concentration (volume %) in the freshness preservation bag immediately after filling with the nitrogen gas and the oxygen concentration (volume %) in the freshness preservation bag t days after filling with the nitrogen gas are measured, and the oxygen transmission rate [cc/day·atm] is calculated from the following formula (1).
Formula (1): Oxygen permeability [cc/day·atm]={(Ct−C0)/k}×V÷t
However, in formula (1),
Ct: Oxygen concentration (volume%) in the freshness preservation bag t days after filling with nitrogen gas
C0: Oxygen concentration (volume%) in the freshness-preserving bag immediately after filling with nitrogen
V: Amount of nitrogen gas filled (cc)
t: time elapsed since gas filling (days)
k: concentration correction coefficient (set to 21 in consideration of the oxygen concentration in the atmosphere)
respectively. The freshness-preserving bag according to claim 1,
The freshness-preserving bag has an oxygen transmission rate of 3 to 30 ([cc/day·atm]/cm) per length (cm) of the back-pasted portion. The freshness-preserving bag according to claim 1 or 2,
The freshness-preserving bag has a width of 2 to 50 mm. The freshness-preserving bag according to claim 1 or 2,
The freshness-keeping bag has a plurality of communicating regions, and the number of the communicating regions is 0.50 to 250 per 10 ^cm2 area in a plan view of the back adhesive portion. The freshness-preserving bag according to claim 1 or 2,
The freshness-keeping bag has a distance between adjacent communicating regions at an end of the back-pasting portion on the bag body side of 1.0 to 300 mm. The freshness-preserving bag according to claim 1 or 2,
The freshness-keeping bag has a geometric pattern formed by alternately arranging the communicating regions and the joining regions in the longitudinal direction of the backing portion. The freshness-preserving bag according to claim 6,
The freshness-keeping bag has pattern constituent units of the geometric pattern that include one or more shapes selected from a straight line, a rectangle, a circle, and a curve. The freshness-preserving bag according to claim 1 or 2,
The freshness-keeping bag has a strip-shaped non-sealed portion extending from the upper end to the lower end of the back-attached portion on the side opposite to the bag body. The freshness-preserving bag according to claim 8,
The freshness-keeping bag has a width of 1 to 40 mm in the band-shaped non-sealed portion. The freshness-preserving bag according to claim 1 or 2,
The freshness-preserving bag, wherein the thickness of the synthetic resin film is 20 to 200 μm. The freshness-preserving bag according to claim 1 or 2,
The synthetic resin film is a film containing one or more selected from polyethylene, ethylene copolymer, polypropylene, polyvinyl chloride, polystyrene, acrylic resin, polyester resin, and polyamide resin, or a multilayer film containing the film. A package in which fruits and vegetables are contained in the freshness-preserving bag body according to claim 1 or 2. A freshness preservation method in which fruits and vegetables are stored in the bag body of the freshness preservation bag according to claim 1 or 2.

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