JP7266360B2 - Freshness-preserving packaging bag for root vegetables, package containing root vegetables, method for preventing germination of root vegetables, and method for preventing greening of root vegetables - Google Patents

Description

TECHNICAL FIELD The present invention relates to a freshness-preserving packaging bag for root vegetables, a package containing root vegetables, a method for preventing germination of root vegetables, and a method for preventing greening of root vegetables.

Fruits and vegetables continue to breathe even after harvesting, and the more vigorously they breathe, the more likely they are to deteriorate. The respiration of fruits and vegetables is suppressed under moderate oxygen and carbon dioxide environments different from the atmospheric composition. When the fruits and vegetables are stored under such conditions, deterioration and ripening of the fruits and vegetables are suppressed. Therefore, in recent years, as a method for packaging fruits and vegetables, a method called MA (Modified Atmosphere) packaging is used to maintain the freshness of fruits and vegetables. The technique called MA packaging realizes an oxygen and carbon dioxide environment that is more suitable for preserving fruits and vegetables than air by adjusting the balance between the respiration rate of fruits and vegetables wrapped in the packaging material and the gas permeation rate of the packaging material. (Patent Documents 1 to 3, etc.).

JP-A-2-85181 JP-A-9-252718 JP 2007-186248 A

However, it has been found that, even with the use of conventional freshness-preserving techniques for fruits and vegetables, deterioration of freshness and spoilage of root vegetables such as potatoes and taros cannot be sufficiently suppressed in some cases.
Specifically, root vegetables that grow buried in the ground are different from fruits and other fruits that grow under light. increases, and as a result, deterioration tends to occur more easily. In particular, in potatoes and the like, germination and greening progress under an inappropriate storage environment, and solanine, a toxic substance, is produced, which may cause problems such as food poisoning.

The present invention has been made in view of such circumstances, and an object of the present invention is to sufficiently prevent germination and greening in the storage of root vegetables such as potatoes and taros.

The present inventors have made intensive studies to solve the above problems. As a result, in a freshness-preserving packaging bag for root vegetables using a perforated synthetic resin film having micropores, by setting the pore diameter of the micropores, the oxygen permeability, the water vapor permeation amount, etc. within an appropriate range, the above problem can be solved. found to be able to solve Specifically, in order to stably suppress the deterioration or putrefaction of root vegetables, the present inventors appropriately control the balance between the oxygen permeability and the water vapor permeability in the freshness-preserving packaging bag for root vegetables. It was found that this is effective as the design guideline.

According to the invention,
A freshness-preserving packaging bag for root vegetables, which is composed of a perforated synthetic resin film provided with micropores and for containing root vegetables as a content,
The micropores have a pore diameter of 50 μm or more and 350 μm or less,
The perforated synthetic resin film has an oxygen permeability per 10 μm thickness at 23° C. and 50% RH of 900 [cc/m ² ·day・atm] or more and 5000 [cc/m ² ·day・atm] or less,
The water vapor permeation amount per 10 μm thickness of the perforated synthetic resin film at 40° C. and 90% RH is 110 [g/m ² ·day] or more and 500 [g/m ² ·day] or less,
In the packaging body in which the root vegetables are contained as the contents in the inner space of the freshness-preserving packaging bag for root vegetables, the water vapor permeation amount per 100 g of the contents at 40° C. and 90% RH of the packaging body is 0.5 [g/100 g day] or more and 10 [g/100 g day] or less,
A freshness-preserving packaging bag for root vegetables is provided, wherein the perforated synthetic resin film has a thickness of 20 μm or more and 40 μm or less.

Moreover, according to the present invention,
A root vegetable-containing package is provided in which the root vegetable is sealed in the inner space of the freshness-preserving packaging bag for root vegetables.

Moreover, according to the present invention,
There is provided a method for preventing germination of root vegetables, which comprises a step of sealing the freshness-preserving packaging bag for root vegetables after housing the root vegetables in the internal space of the freshness-preserving packaging bag for root vegetables.

Moreover, according to the present invention,
There is provided a method for preventing greening of root vegetables, comprising a step of sealing the freshness-preserving packaging bag for root vegetables after housing the root vegetables in the inner space of the freshness-preserving packaging bag for root vegetables.

ADVANTAGE OF THE INVENTION According to this invention, germination and greening can fully be prevented in preservation|save of root vegetables, such as a potato and a taro.

Embodiments of the present invention will be described below.

<Freshness preserving packaging bag for root vegetables>
The freshness-preserving packaging bag for root vegetables of the present embodiment (hereinafter also referred to as "main packaging bag" or simply "packaging bag") is a packaging bag for containing root vegetables as a content, and is provided with micropores. It consists of a perforated synthetic resin film. Here, the hole diameter of the micropores is 50 μm or more and 350 μm or less, and the oxygen permeability per 10 μm thickness of the perforated synthetic resin film at 23° C. and 50% RH is 750 [cc/m ² ·day · atm] or more and 12000 [cc/m ² ·day · atm] or less, and the amount of water vapor permeation per 10 μm thickness of the perforated synthetic resin film at 40 ° C. and 90% RH is 100 [g/m ² ·day] or more and 1000 [g / m ² ·day] or less.

The reason why the present packaging bag can sufficiently prevent deterioration of freshness and spoilage in the preservation of root vegetables such as potatoes and taros is not necessarily clear. However, it is probable that if an appropriate amount of root vegetables is sealed in this packaging bag, the balance between respiration rate and transpiration rate of root vegetables will be highly controlled, and the optimal oxygen/carbon dioxide environment, humidity, etc. for preservation of root vegetables will be realized. It is considered to be for

In addition, the oxygen permeability and the amount of water vapor permeation can be changed by changing the pore size of the micropores, changing the material of the synthetic resin film, changing the thickness of the synthetic resin film, changing the manufacturing method of the synthetic resin film (for example, with or without stretching), etc. A desired value can be obtained by

Specifically, in order to obtain a suitable synthetic resin film, it is important to highly control various factors relating to the following three conditions. That is, a useful packaging bag can be produced by using a synthetic resin film obtained by a production method that highly controls various factors related to the following three conditions. The synthetic resin film used for the present packaging bag can be produced by highly controlling various factors related to the following three conditions and combining other known production conditions.
(1) Combination of resin materials used to form the synthetic resin film (2) Balance between the layer structure of the synthetic resin film and the thickness of each layer that constitutes the synthetic resin film (3) Pore size and density of micropores

The components that the present packaging bag has or may have will be described below.

The pore size of the micropores of the present packaging bag is 50 μm or more and 350 μm or less, more preferably 55 μm or more and 180 μm or less, still more preferably 60 μm or more and 100 μm or less.
The shape of the micropores is typically a perfect circle (including cases where it can be regarded as a substantially perfect circle), but other shapes such as an ellipse, a semicircle, a crescent, and a polygon can also be used. may
In the present specification, the pore size of a micropore refers to the diameter when the shape of the micropore can be regarded as a perfect circle or substantially a perfect circle; The diameter of a perfect circle equal to the area.

In addition, the number of micropores provided in the synthetic resin film is preferably 1 or more and 100 or less per 1 m ² of the film from the viewpoint of highly controlling the oxygen permeability, water vapor permeability, etc. of the packaging bag, It is more preferably 1 or more and 50 or less per 1 m ^{2 of} film, still more preferably 1 or more and 30 or less per 1 ^{m 2 of} film, and particularly preferably 1 or more and 20 or less per 1 m 2 of film. , and most preferably 1 or more and 10 or less.

Moreover, the number of micropores may be, for example, one or more per package, or two or more, from the viewpoint of highly controlling the oxygen permeability, water vapor permeability, and the like of the present packaging bag. On the other hand, the upper limit of the number of micropores per package may be, for example, 10 or less, 5 or less, or 3 or less.

Appropriate adjustment of the pore size, shape, number, etc. of micropores is considered to facilitate appropriate control of the respiration rate of root vegetables in a state of preservation.

The method of forming micropores in the synthetic resin film is not particularly limited. For example, there are a processing method using a hot needle, a method of perforating with a laser beam, and the like.

・Oxygen permeability
The perforated synthetic resin film that constitutes the present packaging bag has an oxygen permeability per 10 μm thickness of 750 [cc/m ² day atm] or more and 12000 [cc/ m ² · day · atm] or less. This numerical value is preferably 900 [cc/m ² ·day · atm] or more and 5000 [cc/m ² ·day · atm] or less, more preferably 1100 [cc/m ² ·day · atm] or more and 2500 [cc/ m ² · day · atm] or less.

The oxygen permeability per 10 μm thickness A [cc/m ² · day · atm] is the oxygen permeability of the synthetic resin film of the packaging bag at 23° C. and 50% RH a [cc/m ² · day·atm] and the thickness of the synthetic resin film is W [μm], it is calculated by the following formula.
A = a x (W/10)

Here, the value of the oxygen transmission rate of the synthetic resin film is determined, for example, using an oxygen transmission rate measuring device (Oxytran (registered trademark) OX-TRAN 1/50) manufactured by MOCON Co., Ltd., according to JIS K7126-2. can be measured by a method in accordance with Annex B of In addition, the value of the oxygen permeability of the synthetic resin film is, for example, the oxygen concentration in the packaging bag for each of the packaging bag immediately after being filled with nitrogen and the packaging bag after being left for a certain period of time after being filled with nitrogen. can also be measured and calculated from the oxygen concentration gradient.

・Water vapor permeation amount The perforated synthetic resin film that constitutes the present packaging bag has a water vapor permeation amount per 10 μm thickness at 40° C. and 90% RH of 100 [g/m ² day] or more and 1000 [g/m ^{2 day} ]. day] or less. This numerical value is preferably 110 [g/m ² ·day] or more and 500 [g/m ² ·day] or less, more preferably 120 [g/m ² ·day] or more and 250 [g/m ² ·day] or less. is.

In addition, this water vapor permeation amount B [g/m ² ·day] per 10 μm thickness is the oxygen transmission rate of the synthetic resin film of the present packaging bag at 40 ° C. and 90% RH b [g/m ² · day]. , where W [μm] is the thickness of the synthetic resin film, it is calculated by the following formula.
B=b×(W/10)

・Amount of water vapor permeation per 100 g of contents
The perforated synthetic resin film that constitutes the present packaging bag, in the package containing root vegetables as the content in the inner space of the present packaging bag, has a moisture content per 100 g of the content at 40 ° C. and 90% RH of the package. The permeation amount is preferably 0.5 [g/100 g·day] or more and 10 [g/100 g·day] or less. This numerical value is preferably 1 [g/100 g·day] or more and 8 [g/100 g·day] or less, more preferably 2 [g/100 g·day] or more and 7 [g/100 g·day] or less.

The water vapor permeation amount C [g/100 g day] per 100 g of the contents of the package is the water vapor permeation amount X [g/m ² day] of the film and the mass Y [g] of the contained contents. , and the inner area Z [m ² ] of the packaging bag, it is calculated by the following formula.
C = {(X/Y) x 100} x Z

Here, the value of the water vapor transmission rate at 40° C. and 90% RH is obtained by using, for example, a water vapor transmission rate measuring device (PERMATRAN (registered trademark) PERMATRAN-W 3/61) manufactured by MOCON. It can be measured by a method conforming to JIS K7129B. The water vapor permeation amount of the synthetic resin film can also be measured by a method conforming to JIS Z0208 (cup method).

・Materials, layer structure, etc. of the perforated synthetic resin film The synthetic resin that constitutes the perforated synthetic resin film is not particularly limited as long as the obtained perforated synthetic resin film satisfies the above-mentioned oxygen permeability and water vapor permeability. . 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 6 nylon. These may be homopolymers, may be copolymers of two or more kinds, or may contain two or more kinds of these homopolymers or copolymers.
More specifically, the above 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 Copolymers such as polyethylene, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-propylene copolymers, ethylene-α-olefin copolymers, and ionomers are included. These resins may be used alone, or two or more of these resins or these resins and other resins may be used in combination.

It is preferable that the perforated resin film used for the present packaging bag has an outer surface formed of a resin material containing a polyamide resin. By doing this, it is possible to reduce the amount of oxygen permeation from the outside of the packaging bag, while maintaining the freshness of the root vegetables stored inside the packaging bag, and making it easier to control the conditions that can induce environmental dormancy of the root vegetables. is. Therefore, not only the outer surface but also the inner surface of the present packaging bag may be formed of a resin material containing polyamide resin. In other words, the perforated resin film that constitutes the present packaging bag may be a single-layer film made of a resin material containing polyamide resin.

One surface of the perforated resin film used for the packaging bag is a resin material containing an ethylene-vinyl alcohol copolymer so that the inner surface of the packaging bag has a resin inner layer containing the ethylene-vinyl alcohol copolymer. It is preferably formed by By doing so, the dew condensation prevention property on the inner surface of the packaging bag can be further improved. A known anti-fogging agent may be contained in the material forming the resin inner layer that forms the inner surface of the packaging bag.

When the perforated resin film is a multilayer film, one surface of the film is made of a resin material containing an ethylene-vinyl alcohol copolymer. Moreover, it is preferable that the other surface is made of a resin material containing a polyamide resin. By doing so, it is possible to stably maintain the environmental conditions in the packaging bag for a long period of time under conditions that can induce environmental dormancy of root vegetables, and to realize a packaging bag that is excellent in dew condensation prevention. is possible.

A case where the perforated resin film has a multilayer structure will be described below.

The perforated resin film may be a multi-layer film having three or more layers with intermediate layers. The thickness of the intermediate layer is preferably 0.001 μm or more and 0.5 μm or less, more preferably 0.01 μm or more and 0.45 μm or less. As a material for forming the intermediate layer, a known anchor coating agent can be used.

The thickness of the resin inner layer (for example, the thickness when the ethylene-vinyl alcohol copolymer is used as the resin inner layer) is preferably 0.1 μm or more and 2 μm or less, more preferably 0.5 μm or more1. 5 μm or less.
Furthermore, the thickness of the resin outer layer (for example, the thickness when the outer surface of the packaging bag is formed from the resin material containing the polyamide resin) is preferably 10 μm or more and 50 μm or less, more preferably 20 μm or more and 40 μm or less. be.

The method of forming the film is not particularly limited, but methods such as extrusion, inflation, calendering, etc., can be employed. When molding the film, if necessary, additives such as an antifog agent may be kneaded, or two or more resins may be blended. In addition, the film may be subjected to stretching treatment, annealing, or the like. A sealant layer may be provided on the surface of these films, or a film coated to impart some function may be used. Furthermore, these films may be transparent, opaque, or printed.

The thickness of the perforated synthetic resin film may be, for example, 20 μm or more and 40 μm or less. By making it 20 μm or more, it is possible to obtain sufficient strength as a packaging bag. Moreover, the production cost can be suppressed by setting the thickness to 40 μm or less.

The perforated synthetic resin film may be either transparent or opaque, but it should be transparent from the viewpoint of consumer's internal visibility when the package containing the root vegetables is distributed to the market. is preferred.

・Root vegetables Specific examples of root vegetables contained in this packaging bag include potatoes, taro, sweet potato, Chinese yam, yam, wild yam, konnyaku potato, taro, etc., turnip, wasabi, burdock, ginger, Carrots, shallots, lotus roots, radishes, lily roots, and the like. Among others, the present packaging bag is preferably used for preserving potatoes and taros. That is, the present packaging bag is preferably used as a freshness-preserving packaging bag for potatoes or taros. By doing so, it is possible to obtain a packaging bag capable of suppressing phenomena such as germination and greening that are specific to potatoes, taros, etc., that is, deterioration of freshness due to factors other than general ripening and aging.

<Package containing root vegetables>
The present packaging bag described above is used by sealing the opening of the bag after accommodating the root vegetables therein. That is, it is possible to produce a root vegetable-containing package in which root vegetables are sealed in the inner space of the present packaging bag.

In order to seal the packaging bag when producing the package containing root vegetables, the opening may be heat-sealed, or members such as a back sealing tape, binding band, rubber band, and caulking may be used. . Above all, from the viewpoint of appropriately controlling the respiration rate of the root vegetables accommodated in the packaging bag, it is preferable to apply a heat-sealing treatment to the opening in order to seal the packaging bag.

The inner surface area of the package may be appropriately set according to the shape, size, etc. of the root vegetables to be packaged.
For example, considering the storage and distribution of general root vegetables, it is conceivable to set the inner dimensions of the packaging bag to about 200 mm×300 mm when storing 500 to 800 g of root vegetables.
As another aspect, the inner surface area of the package per 100 g of root vegetables is 100 cm ² or more and 1000 cm ² or less as one mode, and 200 cm ² or more and 700 cm ² or less as another mode.

<Method for preventing germination of root crops>
The method for preventing germination of root vegetables in the present embodiment preferably includes a step of sealing the freshness-preserving packaging bag for root vegetables after accommodating the root vegetables in the inner space of the freshness-preserving packaging bag for root vegetables. Examples of root vegetables include potatoes and taros. In other words, the method for preventing germination of root vegetables in this embodiment can be said to be the method for preventing germination of potatoes and taros.

<Method for preventing greening of root crops>
The method for preventing greening of root vegetables in the present embodiment preferably includes a step of sealing the freshness-preserving packaging bag for root vegetables after housing the root vegetables in the inner space of the freshness-preserving packaging bag for root vegetables. Examples of root vegetables include potatoes and taros. In other words, the method for preventing greening of root vegetables in this embodiment can be said to be the method for preventing greening of potatoes and taros.

In the sprouting prevention method and greening prevention method described above, the temperature after sealing is preferably 15° C. or higher and 30° C. or lower in order to maximize the effect of sprouting prevention and/or greening prevention. In addition, from the viewpoint of minimizing greening, it is preferable to leave the packaging bag in which the root vegetables are sealed in a dark place as much as possible. In actual distribution and sales of root vegetables, it is impossible to leave the root vegetables in a completely dark place. If it is a prevention method, it is possible to sufficiently obtain the effect of preventing germination and/or preventing greening.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can also be adopted.
Examples of reference forms are added below.
1.
A freshness-preserving packaging bag for root vegetables, which is composed of a perforated synthetic resin film provided with micropores and for containing root vegetables as a content,
The micropores have a pore diameter of 50 μm or more and 350 μm or less,
The perforated synthetic resin film has an oxygen permeability per 10 μm thickness at 23° C. and 50% RH of 750 [cc/m ² ·day・atm] or more and 12000 [cc/m ² ·day・atm] or less,
Freshness for root vegetables, wherein the perforated synthetic resin film has a water vapor permeation amount per 10 μm thickness at 40° C. and 90% RH of 100 [g/m 2 ·day ^] or more and 1000 [g/m ² ·day] or less. Retaining packaging bag.
2.
In the packaging body in which the root vegetables are contained as the contents in the inner space of the freshness-preserving packaging bag for root vegetables, the water vapor permeation amount per 100 g of the contents at 40° C. and 90% RH of the packaging body is 0.5 [g/100 g·day] or more and 10 [g/100 g·day] or less; The freshness-preserving packaging bag for root vegetables described in .
3.
1. The root vegetable is potato or taro; or 2. The freshness-preserving packaging bag for root vegetables described in .
4.
1. The inner surface of the freshness-preserving packaging bag for root vegetables is formed of a resin inner layer containing an ethylene-vinyl alcohol copolymer; to 3. The freshness-preserving packaging bag for root vegetables according to any one of .
5.
1. The outer surface of the freshness-preserving packaging bag for root vegetables is formed from a resin outer layer containing a polyamide resin material. to 4. The freshness-preserving packaging bag for root vegetables according to any one of .
6.
1. The perforated synthetic resin film has a thickness of 20 μm or more and 40 μm or less. to 5. The freshness-preserving packaging bag for root vegetables according to any one of .
7.
1. to 6. A package containing root vegetables, wherein the root vegetables are sealed in the inner space of the freshness-preserving packaging bag for root vegetables according to any one of the above.
8.
1. to 6. A method for preventing germination of root vegetables, comprising a step of sealing the freshness-preserving packaging bag for root vegetables after containing the root vegetables in the internal space of the freshness-preserving packaging bag for root vegetables according to any one of 1.
9.
1. to 6. A method for preventing greening of root vegetables, comprising a step of sealing the freshness-preserving packaging bag for root vegetables after containing the root vegetables in the inner space of the freshness-preserving packaging bag for root vegetables according to any one of .

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples, but the present invention is not limited to these.

<Production of synthetic resin film>
Nylon 6 (UBE nylon (registered trademark) 1022B manufactured by Ube Industries, Ltd.) was prepared as a material for forming a resin outer layer that constitutes the outer surface of the packaging bag.
In addition, as a material for forming the resin inner layer that constitutes the inner surface of the packaging bag, an anti-fogging agent containing glycerin laurate and decaglycerin laurate at a ratio of 97 parts by weight: 3 parts by weight was used together with ethylene and vinyl alcohol. Preparation was made by adding 2.5% by weight to the total amount of the polymer resin.
These materials were put into a T-die extruder, and a synthetic resin film having a two-layer structure was produced by a co-extrusion T-die method. In this example, three types of synthetic resin films (Examples 1 to 3, Table 1) having different thicknesses of each layer and the thickness of the entire film were obtained by changing the extrusion conditions and the like.

After cutting the obtained synthetic resin film into a suitable size, a substantially circular hole was formed in the synthetic resin film with a hot needle. The pore diameter was the diameter shown in Table 1. In addition, the number of holes (density) was adjusted so that the number of holes in the finally obtained packaging bag was the number shown in Table 1.

After forming the holes, the two films were superimposed and heat-sealed on three sides using an impulse sealer (FI-400Y-10PK, manufactured by Fuji Impulse Co., Ltd.) to form a heat-sealed portion with a width of 10 mm. Thus, packaging bags of Examples 1 to 3 were produced. The size (inner dimension) of the bag was the value shown in Table 1.

The packaging bags of Comparative Examples 1 and 2 were produced using a commercially available biaxially oriented polypropylene film (OPP). The method of forming holes and the method of making the film into a packaging bag are the same as those described above. The packaging bag of Comparative Example 1 was not formed with holes.

The obtained freshness-preserving packaging bag for root vegetables was subjected to the following measurements and evaluations.

<Measurement of oxygen permeability>
(1) Preparation of packaging bags The packaging bags of Examples 1 to 3 and Comparative Examples 1 and 2 were heat-sealed on all four sides to seal the packaging bags.
All the following operations were performed in the atmosphere.

(2) Encapsulation of Nitrogen Gas After sealing the above packaging bag, degassing was performed using an aspirator until both sides of the packaging bag were stuck together. Next, the packaging bag was filled with nitrogen gas (purity of 99.9% or more) using a white hard syringe. The filling amount of nitrogen gas was as large as possible within a range that does not apply tension to the synthetic resin film, and was measured using the scale of the syringe. The gas was degassed and injected by inserting an injection needle into the bag. When sticking a needle, a double-faced tape was attached to the film, and an adhesive tape made of polypropylene film (hereinafter referred to as "PP tape") was attached thereon. After the needle was pulled out, the needle hole was immediately closed with a PP tape. The tape attached to the bag was made to fit within an area of 4.5 cm ² or less. However, the PP tape was made so as not to block the fine holes punched in the packaging bag.

(3) Measurement of Initial Oxygen Concentration The initial oxygen concentration (C ₀ ) in the packaging bag immediately after filling with nitrogen gas (t=0) was measured. The gas in the packaging bag was sampled and the initial oxygen concentration (C ₀ ) in the bag was determined by gas chromatography (TCD). C ₀ was 0.2% or less, above which the work was redone. The sampling gas for oxygen concentration measurement was set to 10 cc or less. When injecting into the gas chromatography, about 1 cc of sampling gas was injected.

(4) Storage of packaging bag Next, the packaging bag whose initial oxygen concentration was measured was stored in a constant temperature and constant humidity chamber in which the conditions inside the chamber were controlled at 23°C and 50% RH. At this time, the packaging bag was left undisturbed so as not to put anything on the packaging bag and not to blow the wind of the fan of the constant temperature/humidity chamber directly.

(5) Measuring the oxygen concentration in the packaging bag during storage and calculating the oxygen permeability The oxygen concentration in the bag should be measured within the range of 1% to 7% immediately after filling with nitrogen gas and after 3 hours or more. A total of 3 or more points, 2 or more, must be measured, 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 (C _t ). If the number did not hold, the test was retested.
In addition, if the oxygen permeability of the synthetic resin film forming the packaging bag is too high, the oxygen concentration in the bag increases too quickly, and if the above conditions cannot be satisfied, one of the synthetic resin films forming the packaging bag The part is pasted with a film of the same material that is smaller than the film whose oxygen permeability is known, and the packaging bag is remade, and the value of the oxygen concentration in the bag is measured again by the method described above. bottom. At this time, the surface area of the packaging bag was obtained by subtracting the oxygen permeability of the known film portion from the obtained value of oxygen permeability, excluding the portion bonded to another film, which is known. It was taken as the oxygen permeability of the film. The oxygen transmission rate was calculated by the following formula using the value of the longer elapsed time.
Formula: F = (C _t - C ₀ )/21 x V/t/s
however,
F: Oxygen permeability of synthetic resin film (cc/m ² · day · atm)
C _t : Oxygen concentration (%) in the bag after t hours after nitrogen gas filling
C ₀ : Oxygen concentration in bag immediately after nitrogen gas filling (%)
V: Amount of filled nitrogen gas (cc)
t: Elapsed time from gas filling (hr)
s: surface area of bag (m ² )

<Measurement of Water Vapor Permeation Amount>
The water vapor permeation amount of the synthetic resin film was measured by a method based on JIS Z0208 (cup method). The measurement conditions were set to 40° C. and 90% RH. Moreover, the weighing was carried out under the conditions of 23° C. and 50% RH. The unit is g/m ² ·day.
In addition, if the method conforming to JIS Z0208 (cup method) cannot be used because the moisture permeability of the synthetic resin film is too high, calcium chloride is heat-sealed in a 50 mm x 100 mm (inner dimension) bag instead of the cup. and the amount of water vapor permeation was calculated from the change in the weight of the bag over time. In this case, the storage period of the bag was set within a range in which the calcium chloride did not completely absorb moisture.

<Evaluation on germination>
Using the packaging bags of Examples 1 to 3 and Comparative Examples 1 and 2, packages containing root vegetables were produced by sealing potatoes in the inner space of the packaging bags by the following method.

Potato-containing packages were produced by sealing and packaging the grams of potatoes (variety: May Queen) shown in Table 1 in the packaging bags of Examples 1 to 3 and Comparative Examples 1 and 2, respectively.
Each of the prepared root vegetable-containing packages was stored at 18° C. for 8 days under the same conditions.

Presence or absence of greening: The degree of greening of the root vegetables housed in the package stored at 18°C for 8 days was visually observed and evaluated according to the following criteria.
◯: Greening of root vegetables could not be visually confirmed.
x: Greening of root vegetables was confirmed visually.

Presence or absence of germination/rooting: The germination state of the root vegetables housed in the package stored at 18°C for 8 days was visually observed and evaluated according to the following criteria.
○: It was not possible to visually confirm that the root vegetables had sprouted or rooted.
x: It was confirmed visually that the root vegetables had sprouted or rooted.

As can be seen from Table 1 above, all of the packaging bags of Examples 1 to 3 were able to suppress germination and greening of root vegetables.

Claims (7)

A freshness-preserving packaging bag for root vegetables, which is composed of a perforated synthetic resin film provided with micropores and for containing root vegetables as a content,
The micropores have a pore diameter of 60 μm or more and 100 μm or less,
The perforated synthetic resin film has an oxygen permeability per 10 μm thickness at 23° C. and 50% RH of 900 [cc/m ² ·day・atm] or more and 5000 [cc/m ² ·day・atm] or less,
The perforated synthetic resin film has a water vapor permeation amount per 10 μm thickness at 40° C. and 90% RH of 110 [g/m ² ·day] or more and 500 [g/m ² ·day] or less ,
A freshness-preserving packaging bag for root vegetables, wherein the perforated synthetic resin film has a thickness of 20 μm or more and 40 μm or less. 2. The freshness-preserving packaging bag for root vegetables according to claim 1, wherein said root vegetables are potatoes or taros. 3. The freshness-preserving packaging bag for root vegetables according to claim 1, wherein the inner surface of the freshness-preserving packaging bag for root vegetables is formed from a resin inner layer containing an ethylene-vinyl alcohol copolymer. The freshness-preserving packaging bag for root vegetables according to any one of claims 1 to 3, wherein the outer surface of the freshness-preserving packaging bag for root vegetables is formed from a resin outer layer containing a polyamide resin material. A package containing root vegetables, wherein the root vegetables are sealed in the inner space of the freshness-preserving packaging bag for root vegetables according to any one of claims 1 to 4 ,
Root vegetable-containing package, wherein the package has a water vapor permeation amount per 100 g of the content at 40° C. and 90% RH of 0.5 [g/100 g·day] or more and 10 [g/100 g·day] or less. . Germination of root vegetables, comprising a step of sealing the freshness-preserving packaging bag for root vegetables after housing the root vegetables in the internal space of the freshness-preserving packaging bag for root vegetables according to any one of claims 1 to 4. Prevention method. Greening of root vegetables, comprising a step of sealing the freshness-preserving packaging bag for root vegetables after containing the root vegetables in the internal space of the freshness-preserving packaging bag for root vegetables according to any one of claims 1 to 4. Prevention method.