JPS6344837A - Method for keeping freshness of green vegetable - Google Patents

Abstract

PURPOSE:To prevent water-rot of green vegetable having vigorous physiological activity and to keep the green vegetable in highly fresh state over a long period, by packaging the green vegetable in a packaging bag made of a specific multi- layered film. CONSTITUTION:The multi-layered film used in the present process has water- vapor permeability, oxygen permeability and carbon dioxide gas permeability adjusted within respective specific ranges, is provided with an antifogging agent on at least one of the surfaces to enable continuous antifogging effect in the course of repeating the temperature change between 0 deg.C and 40 deg.C and gives a fusing seal strength of >=3.0kg-cm/15mm when subjecting the surface layer to fusing seal at 270 deg.C. The film is formed in the form of a bag having at least 3 closed sides facing the surface layer inward. A part or the whole surface of said bag is provided with at least one opening having total opening area of 0.02-3.5% of the total area of the bag. Green vegetable having vigorous physiological activity such as cucumber, green soybean, etc., is put into the above packaging bag.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to vegetables, root vegetables, fruits, flowers, flowering trees, mushrooms, etc. (hereinafter referred to as fruits and vegetables in a broad sense hereinafter). , relates to a method that can maintain the freshness of fruits and vegetables at the time of harvest for a long period of time, targeting fruits and vegetables that have intense physiological effects even after harvest.

[Prior art] In recent years, fruits and vegetables such as fresh vegetables, fruits, fresh flowers, and mushrooms have been grown from open fields to four-car multiplex cultivation in horticultural facilities.
In many cases, there has been a shift towards diversified cultivation, and large quantities of fruit and vegetables must be harvested and packaged within a set period of time. In addition, since the harvest period for fruits and vegetables that are mainly grown outdoors is fixed, a large amount of the harvest must be packaged and shipped within a short period of time, and these packaged fruits and vegetables end up in the hands of general consumers. The biggest problem in the distribution process is how to maintain freshness at the time of harvest.

In order to meet these demands, research is actively underway to improve packaging bags with a focus on preserving freshness, and the present applicant has also proposed several improved packaging films and packaging bags.

By the way, fruits and vegetables such as those mentioned above do not immediately lose their physiological effects after being harvested, and especially for a while after being harvested, they continue to maintain their physiological effects to the extent that they are almost the same as before harvest. Furthermore, if they are kept under appropriate storage conditions, their physiological effects will continue for a longer period of time, and as long as they maintain their physiological effects, fruits and vegetables will maintain good freshness. In other words, if it is not stored in a good condition, it will lose its sustained physiological function and will deteriorate prematurely.

It is known that the physiological effects of fruits and vegetables in a packaged state include: - decrease in water content due to transpiration; - consumption of atmospheric oxygen and production of carbon dioxide due to respiration; - production of carbon dioxide and temperature rise due to heat generation. In a sealed state, the oxygen concentration decreases, the carbon dioxide concentration increases, and the internal temperature of the package rises because heat is not dissipated. The respiration process becomes more active above a certain temperature, and at high temperatures, it becomes more susceptible to decomposition due to the stuffiness phenomenon. In addition, the transpiration effect becomes greater in an atmosphere of high temperature or low humidity, and as a result, it becomes more likely to rot in the high temperature and high humidity environment.

Therefore, in order to enhance the freshness preservation effect during storage, taking into consideration the physiological effects described in 2. Attempts have been made to increase the temperature, prevent a decrease in oxygen concentration, prevent an increase in carbon dioxide concentration, and suppress temperature rise. However, these are only temporary measures and do not necessarily make the temperature distribution and gas composition uniform inside the packaging bag, leading to localized decay, especially in areas that cannot be seen from the outside. This can have the unintended consequence of deceiving consumers. Moreover, in the packaging bags for fruits and vegetables that use packaging films that are currently in practical use, the moisture produced by the transpiration of fruits and vegetables or the evaporation of adhering moisture adheres to the inner surface of the packaging bag, causing cloudiness, and the contents become cloudy. In addition to the problem that it becomes difficult to see from the outside, there is also the problem that when fruits and vegetables come into direct contact with the moisture condensed in the cloudy area, so-called water rot occurs.

From this point of view, we have developed packaging that maintains the temperature and gas composition within the bag at a temperature and gas composition suitable for the physiological effects of fruits and vegetables without having to make any holes or cuts in the bag, and that also exhibits excellent antifogging properties. Although the development of bags has been desired, there have not been enough bags available to package fruits and vegetables that have strong physiological effects.

For example, although polyethylene film has a moderate water vapor permeability, it lacks oxygen and carbon dioxide gas permeability, which causes fruits and vegetables to suffocate during short-term storage, resulting in loss of freshness. Although the respiration effect of fruits and vegetables can be maintained for a long period of time due to their permeability to oxygen and carbon dioxide, the water vapor permeability is too high and the evaporation effect of water becomes significant, causing discoloration or wilting of fruits and vegetables in a short period of time. However, it is not possible to maintain good freshness over a long period of time.

Moreover, all of the above-mentioned films have poor antifogging properties, which not only lowers the commercial value in terms of appearance, but also causes so-called water rot when fruits and vegetables come into direct contact with moisture condensed in the cloudy areas.

[Problems to be Solved by the Invention] The present inventors focused on the above-mentioned circumstances, and did not apply openings or cuts to the packaging bag (which also has water vapor permeability, oxygen and Demonstrates carbon dioxide gas permeability,
We conducted research to develop a multilayer film that does not cause clouding on the inner surface. As a result, if the water vapor permeability, oxygen permeability, and carbon dioxide permeability of the multilayer film are specified to be within appropriate ranges, and an appropriate amount of antifogging agent is blended into the multilayer film constituent materials, it is possible to solve the above problems. After confirming that the problem had been resolved, we filed a patent application based on this knowledge.

However, as research progressed into this process, the following facts became clear. In other words, when using a bag made of the multilayer film according to the above-mentioned prior invention, the purpose of preserving freshness is effectively achieved for fruits and vegetables whose physiological effects are relatively mild after harvest, but physiological effects after harvest are also severe. When used to package fruits and vegetables that have physiological effects (e.g. cucumbers, edamame, enokidake, kidney beans, etc.), the oxygen concentration, carbon dioxide concentration, or humidity within the bag will fluctuate significantly, so normal packaging methods are not recommended. It has been found that it is sometimes difficult to follow such rapid fluctuations, making it impossible to maintain the surrounding atmosphere with a gas suitable for the intense physiological effects of the fruits and vegetables, making it impossible to sufficiently achieve the purpose of maintaining freshness. Moreover, when sudden temperature changes occur on tatami mats or at night, or when the food is put in and taken out of the refrigerator, the water vapor inside the bag condenses and water accumulates inside the packaging bag, causing the problem of water rot in fruits and vegetables. It's coming.

The present invention was developed as a result of further research focusing on such problems, and its purpose is to target fruits and vegetables that have strong physiological effects, and to maintain the same effect even when the fruits and vegetables are subjected to rapid temperature changes. It is an object of the present invention to provide a method that not only can maintain the air quality of a packaging bag suitable for the physiological functions of fruits and vegetables, but also can maintain the freshness of fruits and vegetables for a long period of time without causing the problem of water rot due to condensation water. That is.

[Means for Solving the Problems] The configuration of the method of the present invention specified as requirements for achieving the above objectives is as follows: Water vapor permeability is 15 to 200g/m2・24hr・40
°C, oxygen permeability is 3000-35000 CC/I2・24
hr-atm・20℃・90%FLH.

Carbon dioxide scum permeability M 121100~130000cc/
l112・24hr-atm・20℃・90%R
H.

A multilayer film is used, in which an antifogging agent is present in at least one surface layer, and the surface layer has melt-sealing properties, and at least three sides are formed so that the surface layer is on the inside. It is formed in the shape of a closed bag, and one or more openings having a total opening area of 0.02 to 3.5% of the total surface area of the film surface of the bag are formed on a part or the entire surface of the film surface of the bag. The gist is that fruits and vegetables are stored in packaging bags with holes.

[Function] The multilayer film constituting the packaging bag used in the present invention first specifies water vapor permeability, oxygen permeability, and carbon dioxide gas permeability as the first condition, and also Since it is characterized by the presence of an antifogging agent in the surface layer on the contacting side, the reasons for determining each of the above characteristics will be explained below.

Water vapor permeability = 15-200g/rr12・24hr・
40℃ Water vapor permeability is the moisture content released by the evaporation and transpiration of the moisture attached to fruits and vegetables, which maintains appropriate humidity inside the bag, prevents stuffiness caused by excessive humidity, and suppresses spoilage. This is an important property in preventing fruits and vegetables from wilting, discoloration (yellowing or browning), softening, loss of elasticity, etc. due to deficiency, and has a water vapor permeability of 15g/m2/24hr.
・At temperatures below 40℃, fruits and vegetables tend to rot due to swelling caused by excessive humidity;
If the temperature exceeds .degree. C., there will be insufficient humidity inside the packaging bag, and the fruits and vegetables will easily wilt, discolor, etc., and in either case, a satisfactory freshness preservation effect cannot be obtained. The more preferable water vapor permeability is 20 to ensure good freshness retention effect.
~150 g/m'' 24 hours/40°C.

Oxygen permeability: 3,000-35,0OOcc/m2
・24 hr ・atm ・20℃・90% RH Oxygen permeability is an extremely important characteristic for sustaining physiological effects by compensating for the decrease in oxygen concentration due to respiration by permeating and infiltrating external air. 3. Goo c
c/m2・24hr-atm H20℃・90%RH If not vortexed, the respiratory effect is particularly pronounced (high oxygen consumption)
When fruits and vegetables are packaged, the amount of internal oxygen is deficient, resulting in suffocation and not being able to maintain sufficient freshness. On the other hand 35
,000cc/m'・24hr-atm・2.0
If the temperature exceeds 90% RH, there is no risk of oxygen deficiency, but the freshness-keeping effect of fruits and vegetables that develop mold due to the invasion of bacteria from the outside will be reduced.

A more preferable range of oxygen permeability is 4,000 to 20.0.
OOcc/m” 24hr-atm・20℃・90%
It is RH.

Carbon dioxide permeability: 12,000-130.0OOcc
7m2・24hr-atm・20℃・90%RH Carbon dioxide permeability is determined by keeping the gas composition within the packaging bag appropriate.
This property is effective in ensuring the respiration of fruits and vegetables, avoiding carbon dioxide gas damage, and furthermore preventing spoilage due to bacterial invasion and proliferation.
m2.24 hr-atm ・If the temperature is less than 20° C. and 90% RH, the carbon dioxide concentration in the packaging bag will become too high, inhibiting the respiration of fruits and vegetables, and causing a rapid decline in freshness and taste.

On the other hand, 130,000cc 7m2・24hr-atm
・If the temperature exceeds 20℃/90%RH, 002 inside the packaging bag
If the concentration becomes too low, the anti-corrosion effect and the anti-deterioration effect will no longer be effectively exhibited.

A more preferable range of carbon dioxide permeability is 15,000 to 1
00.000cc 7m2-24hr-atm
・20℃・90%RH.

Furthermore, the surface layer of the multilayer film used in the present invention on the side that comes into contact with fruits and vegetables must contain an antifogging agent that exhibits antifogging properties during storage and distribution. That is, in the present invention, the antifogging effect is an extremely important property not only to prevent the inner surface of the packaging bag from becoming cloudy and thereby increasing the product value, but also to prevent the contents from being spoiled by water droplets that are formed due to the progress of fogging. In addition, in order to maintain excellent antifogging properties over a long period of time during the distribution process, it is necessary to take into account temperature changes during storage and distribution. It is desirable that an antifogging agent that exhibits antifogging properties be present in the surface layer.As mentioned above, the present invention is intended for packaging fruits and vegetables that continue to have strong physiological effects even after harvest. Storage at room temperature is preferred rather than frozen storage, but considering the temperature difference between indoors and outdoors in winter, when setting the antifogging properties of the present invention, for example, the r , 0: Anti-fog durability when temperature changes are repeated between 40 degrees Celsius", and in the present invention, it is desirable that the anti-fog property lasts for one day or more as measured by the following measurement method. .

(Anti-fog property evaluation method) Pour 150cc of 40℃ hot water into a 200cc beaker,
Place the sample over the beaker with the anti-fog side facing inside. Thereafter, it was kept at 0°C for 6 hours, and then kept at 40°C for 6 hours. This temperature change is repeated twice (for a total of 24 hours), and judgment is made based on whether the contents of the container can be clearly observed through the film surface.

The type of antifogging agent to be present in the surface layer is not particularly limited, and in addition to conventionally known antifogging agents, all substances that can exhibit antifogging properties such as antistatic agents and lubricating agents may be used. If necessary, two or more types can be used in combination. These antifogging agents can be directly mixed into the surface layer constituent materials, or they can be mixed only into the base layer constituent materials and diffused into the surface layer after lamination, thereby imparting antifogging properties to the surface layer. It is also possible. The amount of antifogging agent present in the surface layer varies depending on the type of antifogging agent, so it is not appropriate to specify it uniformly, but it is preferably 0.3
-3% by weight.

However, if it is less than 0.3% by weight, the antifogging performance will be insufficient, making it difficult to satisfy the characteristics required by the present invention.On the other hand, if it exceeds 3%, the surface layer will whiten and the transparency will decrease. Not only that, but moisture adhering to the inner surface of the bag due to evaporation of fruits and vegetables causes a cloudy phenomenon, resulting in a problem that the product value is significantly reduced.

It is also possible to evaluate the antifogging property of the film in the state before bag making by the surface tension of the surface layer, and the inventors have confirmed that the surface tension is 38.
It has become clear that by adjusting the amount of antifogging agent present so that it is dynes/cm or more, it is possible to ensure antifogging durability that meets the objective.

Next, the packaging bag used in the present invention is made by stacking the above-mentioned multilayer film so that the layer containing the antifogging agent is on the inside and fusing and sealing it on three sides, or by sealing the two sides perpendicular to the folded side. It is made into a bag shape with at least three sides closed by means such as melt-cutting and sealing, and can prevent the seal from peeling off and being opened during filling or distribution of fruits and vegetables. It must have sufficient sealing strength,
Preferably, the seal strength when melt-sealed at 270°C is 3.0 Kg-cm/15 mm or more. If the seal strength is insufficient, the seal portion may be damaged during filling or handling of fruits and vegetables. There is a risk of peeling.

The fusing seal temperature was determined based on the general fusing sealing temperature currently in practical use, but as long as the fusing sealing strength above the set value can be demonstrated under the above fusing sealing conditions, This does not preclude the adoption of a fusing seal temperature outside the range of .

A multilayer film having the above-mentioned characteristics can be manufactured by coextrusion of a synthetic resin or in-line lamination method that can meet the characteristics required by the husband, but considering the relationship with the characteristics required above, The most preferable base layer constituent materials and surface layer constituent materials are as follows.

First, the base layer not only ensures the minimum mechanical strength required for the film, but also has the greatest influence on the permeability of water vapor, oxygen, and carbon dioxide, and should be made of the following materials: A base layer can be obtained which serves the above-mentioned purpose. That is, the base layer constituent materials include: (1) one or more α-olefin copolymers having 2 to 1 carbon atoms; and (1) one consisting of vinyl acetate, acrylic acid, and styrene.
Monomer units of species or more account for 5 to 80% of the total constituents
Lfffi or more of the copolymer occupying the total amount of the copolymer, and the mixing ratio is the former (■): 30 to 90% by weight, the latter (■):
Preference is given to mixtures which are between 10 and 70% by weight. Specific examples of the α-olefin having 2 to 1 carbon atoms constituting the above (2) include ethylene, propylene, butene, hexene, heptene, etc., but the more common ones are ethylene, propylene, and protin. When a random copolymer or a block copolymer of two or more of the above α-olefins is used, a base layer satisfying all of the above-mentioned permeability and strength can be obtained more easily. The copolymerization ratio in this case may be arbitrarily determined depending on the types of α-olefins to be combined. In addition, as for the copolymer constituting the above item (1), one unit of a monomer consisting of vinyl acetate, acrylic acid, and styrene is contained in the total component of the copolymer.
A copolymer containing ~80% by weight is preferable, and the copolymer to be combined with these polymers may be any copolymerizable polymer, but particularly preferred is -olefin, ■acrylic ester,
These include methacrylic acid ester or (1) butadiene.

The weight of one monomer unit consisting of vinyl acetate, acrylic acid and styrene in the copolymer is less than 5% or 8%.
If it exceeds 0%, it will be difficult to satisfy all of the above transmittance requirements, and if it exceeds 80%, there will be a tendency for the haze of the base film to deteriorate, and there will also be a decrease in the sealing performance or Difficulties such as the formation of whiskers on the skin tend to occur.

The mixing ratio of (1) and (2) above is preferably in the range of 30-90% by weight for the former and 10-70% by weight for the latter.By specifying such a mixing ratio range, mechanical properties such as strength can be improved. Of course, it is possible to ensure well-balanced performance in all of the transparency, melt sealability, and each of the above-mentioned permeability.

Incidentally, (1) If the blending ratio of the copolymer is less than 30% by weight, the transparency of the base film may decrease. On the other hand, if the copolymer content exceeds 90% by weight, it may become difficult to keep the gas permeability within the range defined by the present invention. For example, even if the oxygen permeability and the carbon dioxide gas permeability fall within the set ranges, a problem arises in that the water vapor permeability falls outside the set ranges, and in this case, it becomes difficult to obtain a packaging atmosphere suitable for the physiological effects of fruits and vegetables.

In addition, when blending the above items (1) and (2), the melt index of the blend at 230°C is 1 to 100/10m.
It is preferable to select the above-mentioned formulations (1) and (2) so that the weight ratio is 1n, more preferably 2 to 50 g/10ml.

Next, the surface layer constituent material is required to have properties that can maintain excellent antifogging properties over a long period of time due to the presence of an antifogging agent, and it is also necessary to have excellent melt sealing properties, which meet these requirements. As a surface layer constituent material for
Random copolymers or block copolymers obtained from two or more α-olefinic polymers (ethylene, propylene, butene, pentene, hexene, octene, decene, etc.) are preferred, and this copolymer is Used alone or in combination. Particularly preferable surface layer constituent materials for improving the weld sealing properties have a melting point of 80 to 1.
The main component is a 50'e α-olefin homopolymer, copolymer, or a mixture of two or more thereof.

It is a polymer. Methods for making the antifogging agent exist in the surface layer constituent film include a method in which the antifogging agent is mixed into the surface layer constituent material itself, and a method in which an appropriate amount of the antifogging agent is included in the base layer film. It is also possible to adopt a method in which the antifogging agent is transferred into the film constituting the main surface portion by diffusion after lamination. In this case, the amount of antifogging agent mixed into the base film is 0.3 to 3% by weight, more preferably 0.4 to 3% by weight.
2.2% by weight is preferable; if it is less than 0.3% by weight, the amount of diffusion and transfer toward the surface layer film will be insufficient, making it impossible to provide sufficient antifogging performance to the surface layer; %
If it exceeds this value, although the antifogging properties of the surface layer side can be sufficiently enhanced, the surface layer film will undergo a whitening phenomenon and its commercial value will be poor. However, when the base layer film contains 0.3 to 3% by weight of an antifogging agent and is laminated with the surface layer film, the antifogging agent in the base layer film gradually diffuses toward the surface layer film. As a result, good anti-fog properties are maintained over a long period of time.

The means for forming a composite film from the above-mentioned base layer constituent materials and surface layer constituent materials is not particularly limited, and as mentioned above, well-known methods such as coextrusion method and in-line lamination method may be used. There are also no particular restrictions on the thickness of the base layer and surface layer, but taking economic efficiency and physical properties into consideration, the most common thicknesses are the base layer: about 4 to 200 μm, and the surface layer: about 0.3 to 8 μm. . Further, the thickness ratio between the base layer and the surface layer (total thickness of both outer surfaces when the surface layer is the surface layer) is generally 99.5 to 60:0.5 to 4o. The most basic composite form of the film of the present invention is one in which a surface layer and a base layer are laminated, but a surface layer is laminated on both sides of this base layer, and both sides have antifogging properties and heat sealability. or printing on one side of the base layer (the side opposite to the surface layer laminated surface, however, if both surface layers have antifogging properties or heat sealing properties, one of the surface layers) Of course, it is also possible to perform other processing, and all of these are included within the technical scope of the present invention.

In addition, lubricants, anti-blocking agents, antioxidants, ultraviolet absorbers, colorants, antistatic agents, etc. can be further added to the films constituting the base layer and the surface layer, and the multilayer film If desired, the material may be uniaxially or biaxially stretched to improve its physical properties.

The multilayer film obtained in this way is made into a packaging bag by closing at least three sides with the layer containing the antifogging agent on the inner side. If the film is sealed, as mentioned above, the gas permeability of the film alone is not sufficient to cope with changes in internal gas composition and increase in humidity due to the intense physiological effects of fruits and vegetables, resulting in an oxygen-deficient state. If fruits and vegetables lose their physiological function or if there is a sudden change in temperature, the water vapor inside the bag will condense and water will accumulate inside the bag, causing water rot.

Therefore, in the present invention, openings of an appropriate size are provided in a part or the entire surface of the film surface of the packaging bag so that changes in the gas composition within the packaging bag can be immediately averaged out by promoting ventilation inside and outside. These holes eliminate the fluctuations in the gas inside the bag, which cannot be followed by the gas permeability of the multilayer film itself, due to the intense physiological effects of fruits and vegetables, as mentioned above, by promoting ventilation inside and outside, thereby creating an appropriate physiological environment. In addition to the function of retaining moisture, it also prevents water from condensing due to sudden temperature changes, and even if a small amount of condensation occurs, the condensed water quickly flows out of the bag to prevent fruits and vegetables from rotting. In order to effectively exhibit these functions, the total pore area must be 0.02% or more of the surface area of the packaging film surface layer. If the total pore area is less than 0.02%, the effect of promoting internal and external ventilation will be insufficient, and it will not only be difficult to cope with changes in the concentration of gas inside the bag due to intense physiological effects, but also condensed water due to sudden changes in temperature. cannot prevent the occurrence of

On the other hand, if the total pore area is too large, especially when the humidity of the outside air is low, water evaporation will be significant, causing fruits and vegetables to wilt.
Otherwise, not only does it become more likely to yellow, but it also becomes easier for bacteria and the like to invade from the outside, leading to the growth of mold and the like. Furthermore, the total open pore area should be kept within 3.5% of the total area of the bag, since the film strength will be poor and the bag will be torn during packaging or transportation. The openings may be formed on both sides of the bag, or only on one side.

By adjusting the size and number of openings to meet the above requirements, we can prevent condensation water from forming due to the intense physiological effects of fruits and vegetables and sudden changes in outside temperature, without impairing the original function of the packaging bag. Even when the bag is dry, the humidity and gas composition inside the bag can be maintained at a suitable level, and the storage stability of fruits and vegetables can be further improved.

EXAMPLES Next, examples will be given to further clarify the present invention, but the present invention is not limited by the following examples. In the following examples, "1%" means "wt%" unless otherwise specified.

The methods for measuring the permeability of water vapor, oxygen, and carbon dioxide defined in the present invention were as follows.

Water vapor permeability: Measured in accordance with the moisture permeability test method for moisture-proof packaging materials specified by JIS-Z-0208 Method B.

Oxygen permeability and carbon dioxide permeability: Measured according to the gas permeability test method in the "Test method for plastic films for food" specified in JIS-Z-1707. However, each gas was not converted to standard temperature, but was calculated as the volume at 20° C., and as the amount of permeation per 24 hours.

[Example Example 1 Ethylene-propylene copolymer (ethylene content: 5%)
) and an ethylene-vinyl acetate copolymer with a vinyl acetate content of 28%, the former being mixed at a ratio of 65% and the latter 35%, and a propylene-butene-1 copolymer ( Butene-1 content: 18%) and butene-ethylene copolymer (ethylene content: 3.5%) in a weight ratio of 1:1. The surface layer constituent material was mixed with 6% higher fatty acid ester monoglyceride as an antifogging agent, and extruded to create a multilayer film in which the surface layer was laminated on both sides of the base layer by coextrusion method. Temperature: 260°C, cooling: 20°C), followed by a longitudinal stretch ratio of 3 times and a transverse stretch ratio of 8 times.
Double biaxial stretching was performed, and both surfaces were subjected to corona discharge treatment to obtain a three-layer film with a base layer of 16 μm and a surface layer of 2 μm×2 (both sides), totaling 20 μm. One side of this film (
The surface tension on the A') side is 42 dynes/cm, and on the other side (B
) side surface tension was 38 dynes/cm. Table 1 shows the properties of the multilayer film.

In Table 1, 1=The film was made into a bag, fresh shiitake mushrooms were sealed inside, and the temperature was repeatedly changed at 0=40°C (twice/day), and judgment was made based on the presence or absence of clouding after one day.

*2: Strength when melt-sealed at a temperature of 270°C and a sealing speed of 60 times/min This composite film was melt-sealed on two sides with the (A) side facing inside to create a packaging bag measuring 280 mm long x 180 mm wide. . On one side of this packaging bag, as shown in Figure 1,
10 mφ circular holes (total opening area is 00 of the total bag surface area)
6%) was opened, freshly harvested eggplants were placed in the container, and the upper opening was taped (T) to examine changes in freshness during storage.

The respiration rate of eggplant is 2oco2mg/g at 15℃.
-hr, 110 C02mg/Mg-h at 25°C
It is r.

The results are shown in Table 3 below.

Example 2 Propylene/butene-1 copolymer (containing butene-1)
20%) and an ethylene-styrene copolymer (styrene-containing ffi: 40%) in a ratio of 90% of the former and 10% of the latter (0.2% of higher fatty acid ester monoglyceride as an antifogging agent). 8% blend) and propylene-butene-1 copolymer (butene-1 content: 18%)
) and a propylene-butene-1 copolymer (butene-1 content: 30%) in a ratio of 70% of the former and 30% of the latter, but in the same manner as in Example 1. A composite film with a three-layer structure was produced using the following methods (extrusion temperature: 25
0°C, cooling = 25°C). Then, the longitudinal stretching magnification is 2
．． Biaxial stretching was carried out at a 5x stretching ratio and a transverse stretching ratio of 7.8x to obtain a three-layer film with a total thickness of 23 µm, in which a base layer of 20 µm and a surface layer of 1.5 µm each were laminated on both sides. The surface tension of this film on one side (A) is 41 dynes/am, and the surface tension on the other side (B) is 41 dynes/am.
) side was 38 dynes/cm, and both sides showed good antifogging properties of the antifogging agent that had diffused from the base layer.

Properties of the film are shown on the second back.

1 in Table 2 The film was made into a bag, 14 fresh shiitake mushrooms were placed inside, and the temperature was repeatedly changed to 0.240°C (2 times/day).
The judgment was made based on the presence or absence of cloudy weather that subsides after a few days.

*2: Strength of ■ and B when pressed for 1 second at a temperature of 140°C and a pressure of Ikg/cm' This film was melt-sealed on two sides with the (A) side facing inside to create a bag measuring 320mm long x 150mm wide. . This packaging bag has two holes of 3 mmφ on one side of the top and three holes of 4111 IIlφ on one side of the bottom, as shown in Figure 2.
Open pore area ratio: 0.10%), and after charging freshly harvested cucumbers, the upper opening was taped (T) to examine changes in freshness during storage.

The respiration rate of cucumber is 25Co2mg at 15℃.
/g-hr at 25°C 130CO2L118/
Kg-h ``It is.

The results are shown in Table 4 below.

Example 3 Edamame was sealed in the packaging bag obtained in Example 1, and changes in freshness during storage were examined in the same manner. The respiration rate of Eda beans is 15
170 CO2 mg/g-hr at 25°C and 340 CO2 mg/g-hr at 25°C.

The results are shown in Table 5.

For comparison, Table 3.4.5 shows cases without packaging and OPP.
When sealed and packaged with film (biaxially oriented polypropylene film) or PE film (polyethylene film),
and experiments using bags (comparative materials) obtained in exactly the same manner as in Examples 1 to 3 above except that the notch holes were omitted, and bags whose ring frontage area ratio was outside the specified range. The results are also listed.

The evaluation criteria for the freshness retention test shown in Table 3.4.5 were as shown in Table 6.

Example 4 As shown in Table 7, a surface layer constituent material made of a propylene-butene 1 (18%) copolymer (both higher aliphatic 1% monoglyceride) were laminated by coextrusion method, then biaxially stretched 2.5 times vertically x 7.5 times horizontally, and then corona discharged so that the surface tension on both sides was 39 dynes/cm. After processing, a multilayer film was obtained.

The water vapor permeability, oxygen permeability,
Table 8 shows the carbon dioxide permeability, antifogging properties, and fusing seal strength.

Using each multilayer film A-H obtained above,
A 180 mm bag was made, and 8 circular holes with a diameter of 2 mφ (total hole area is 0.14% of the wheel surface area) were made on one side of the bag as shown in Fig. 1, and 70 peas were placed in the holes.
The freshness change during storage was examined in the same manner as above. The storage conditions were 35°C x 70% RH.

The results are summarized in Table 9, and the multilayer films (B, D) meet the specified requirements of the present invention.

Films F and H) have a good freshness retention effect overall, whereas film A has too low water vapor permeability, so moisture does not dissipate, and it has poor odor and odor. Significant deterioration. On the other hand, Film C has too high a water vapor permeability, so the inside becomes dehydrated and discolored.
Softening can be seen. In addition, both films E and G have oxygen permeability and carbon dioxide permeability that are outside the specified range,
The discoloration caused by lack of breathing is particularly noticeable.

Table 9 [Effects of the Invention] The present invention is constructed as described above, and the multilayer film used not only has the permeability of water vapor, oxygen, and carbon dioxide gas appropriately adjusted, but also has the ability to Since the openings are formed with an appropriate size, the fruits and vegetables can maintain their strong physiological effects even after packaging, and the freshness period can be significantly extended. In addition, this multilayer film has excellent anti-fog properties and long-lasting anti-fog properties, so it may become difficult to see the contents during the distribution process, lowering the product value, or the moisture condensing in the cloudy areas may cause fruits and vegetables to be damaged. There is no risk of accelerated spoilage, and moisture condensation is unlikely to occur even if there is a sudden change in temperature, and even if condensation occurs, this condensation can quickly drain out of the bag through the openings. Since the fruit and vegetables leak into the water, there is no risk of water rot, etc., which prevents deterioration of the appearance and product image of fruits and vegetables, and allows them to be supplied to consumers in a fresh state.

[Brief explanation of the drawing]

FIG. 1.2 is a diagram showing the packaging bag used in the example.

Claims (5)

[Claims] (1) Water vapor permeability is 15-200g/m^2・24h
r・40℃, oxygen permeability 3000-35000cc/m^2・24
hr・atm・20℃・90%RH, carbon dioxide gas permeability 12000~130000cc/m^
2, 24 hours, atm, 20°C, 90% RH, using a multilayer film configured such that at least one surface layer contains an antifogging agent and the surface layer has melt-cut sealing properties, It is formed into a bag shape with at least three sides closed so that the surface layer is on the inside, and a part or all of the film surface of the bag is coated with an amount of 0.02 to 3. A method for preserving the freshness of fruits and vegetables, which comprises storing fruits and vegetables with strong physiological effects in a packaging bag provided with one or more holes having a total opening area of 5%. (2) The freshness preservation method according to claim 1, wherein the multilayer film exhibits a sealing strength of 3.0 Kg-cm/15 mm or more when cut and sealed at 270°C. (3) A packaging bag according to claim 1 or 2, wherein at least one surface thereof is made of a multilayer film that exhibits antifogging properties during repeated temperature changes between 0 and 40 degrees Celsius. How to keep it fresh. (4) The base layer constituent material of the multilayer film consists of 30 to 90% by weight of one or more α-olefin copolymers having 2 to 10 carbon atoms, vinyl acetate, acrylic acid, and styrene.
5 to 80% by weight of the total constituent monomer units
The method for preserving freshness according to any one of claims 1 to 3, wherein the method is a mixture of 10 to 70% by weight of one or more copolymers accounting for 10 to 70% by weight of the copolymer. (5) The surface layer constituent material of the multilayer film has 2 to 10 carbon atoms.
Claim 1, which is an α-olefin copolymer of
The freshness preservation method according to any one of items 1 to 4.