JP6694845B2 - Package for keeping freshness of fruits and vegetables and method for keeping freshness of fruits and vegetables - Google Patents

Description

  The present invention relates to a package excellent in freshness-keeping performance of fruits and vegetables containing cabbage, and more specifically, it contains fruits and vegetables containing cabbage in a packaging container having a polymer film and has a specific internal oxygen concentration. The present invention relates to a package.

A gas permeable film is provided in a polymer film base material, and a gas such as oxygen, carbon dioxide, or water vapor is permeable from the gas permeable part, in the food field, for fruits and vegetables, particularly fresh vegetables such as cut vegetables. It is preferably used as a packaging material. By packaging, for example, vegetables and fruits using such a gas-permeable film, it is possible to maintain an oxygen concentration suitable for keeping the freshness of the contents vegetables and fruits, for example, an oxygen concentration of about 1 to 4%. It is known that the contents can be stored while keeping the freshness for a relatively long period.
For example, in Patent Document 1, in a package containing fruits and vegetables which is composed of a polymer film in which fruits and vegetables are sealed, the package is composed of (A) a perforated polymer film and (B) a non-perforated polymer film, (A), (B) at least one of the film characteristics is 25 ℃, relative humidity of 75% measured water vapor permeability is 50 ~ 800gm ^-2 d ^{-1 based} on the effective surface area of the package There is described the packaged body containing fruits and vegetables, wherein the open area ratio of (A) is 3 × 10 ^{−6 to} 7 × 10 ⁻⁴ % with respect to the effective surface area of the packaged body. Specifically, (A) a perforated polymer film, which is made of stretched polypropylene having a thickness of 35 μm, has 95 holes with an average pore diameter of 30 μm, and has 9 holes with an average pore diameter of 60 μm. It is used.

Among the fruits and vegetables, cabbage is one of the most widely distributed vegetables, and the packaging body and the storage method described above can be preferably applied. In particular, cut cabbage obtained by cutting the cabbage has been in increasing demand in recent years because it can be easily served for meals, and since cabbage is one of the most common vegetables for salads, it is highly economical. Has value. Therefore, the packaging and storage method particularly suitable for keeping the freshness of cut cabbage are being actively studied, and the oxygen permeation rate, the carbon dioxide permeation rate, and the water vapor permeation rate of the packaging, and the oxygen concentration in the packaging. , And the carbon dioxide concentration are set to specific values (for example, refer to Patent Document 2).
However, the demand level for consumers and consumers for the quality of cabbage, including cut cabbage, is increasing year by year, and there is a demand for a package that has a longer product life than before in the distribution process. There has been a strong demand for a package that can effectively suppress browning and off-flavor even after such a long period of time.

JP-A-5-168400 JP, 2004-242504, A

In view of the limitations of the background art described above, the present invention is a package in which vegetables and fruits containing cabbage are stored in a packaging container, and the browning and off-flavor of fruits and vegetables containing the cabbage, especially browning, are the limits of the prior art. It is an object of the present invention to provide a package excellent in the function of keeping the freshness of the fruits and vegetables, which can be suppressed over a long period of time exceeding the above.
The present inventor, as a result of diligent studies, controlling the internal oxygen concentration of the initial package after packaging to a predetermined range suppresses browning and off-flavor of fruits and vegetables including cabbage, especially browning for a long period of time, and They have found that they are particularly effective for extending the product life, and have completed the present invention.

That is, the present invention is
[1]
Vegetables and vegetables containing cabbage are stored in a packaging container containing a polymer film, and the internal oxygen concentration after holding the package at 10 ° C. for 72 hours is 1.5 vol% or less. The body.

Hereinafter, each of [2] to [13] is one aspect or a preferred embodiment of the present invention.
[2]
The package according to [1], which suppresses browning and offensive odor of fruits and vegetables containing the cabbage at 72C for 72 hours or more after sealing the package.
[3]
The package according to [1] or [2], wherein the internal oxygen concentration immediately after the packaging is sealed is 23% by volume or less.
[4]
The package according to any one of [1] to [3], wherein nitrogen is further enclosed in the packaging container.
[5]
The package according to any one of [1] to [4], wherein the oxygen permeability of the polymer film is 4500 cc / m ² / atm / day or less at 20 ° C. and 90% RH.
[6]
The package according to any one of [1] to [5], wherein the polymer film has a thickness of 15 to 45 μm.
[7]
The package according to any one of [1] to [6], wherein the polymer film is a stretched polypropylene film, a polyethylene film, or a laminate of a stretched film and a polyethylene film.
[8]
The package according to any one of [1] to [7], wherein the polymer film contains at least one antibacterial agent or is coated with at least one antibacterial agent.
[9]
The package according to any one of [1] to [8], wherein the cabbage is cut cabbage.
[10]
The package according to any one of [1] to [9], which further contains a hygroscopic agent and / or an antibacterial agent.
[11]
A step of storing and sealing fruits and vegetables containing cabbage in a packaging container containing a polymer film having an oxygen permeability at 20 ° C. and 90% RH of 4500 cc / m ² / atm / day or less, and immediately after the sealing The method for maintaining the freshness of fruits and vegetables, which comprises the step of adjusting the oxygen concentration in the packaging container to 23% by volume or less.
[12] The method for keeping freshness of fruits and vegetables according to [11], wherein browning and offensive odor of fruits and vegetables containing the cabbage are suppressed for 72 hours or more under conditions of 2 ° C to 15 ° C after the packaging container is sealed.
[13]
The method for maintaining freshness of fruits and vegetables according to [11] or [12], further including a step of enclosing nitrogen in the packaging container.

  ADVANTAGE OF THE INVENTION According to this invention, by controlling the oxygen concentration inside the package at the initial stage after packaging to a predetermined range, browning and off-flavors of vegetables and fruits containing cabbage, especially browning, can be suppressed for a long period of time, and the product life of the package can be extended. A package that can be used, and a method for maintaining freshness of fruits and vegetables are provided.

Hereinafter, modes for carrying out the present invention will be described.
According to the present invention, fruits and vegetables containing cabbage are stored in a packaging container containing a polymer film, and the internal oxygen concentration after the packaging is kept at 10 ° C. for 72 hours is 1.5 vol% or less. It is a package. That is, the package of the present invention has at least a packaging container and fruits and vegetables stored therein.

Packaging Container The packaging container constituting the package of the present invention comprises a polymer film. Here, "comprising a polymer film" refers to a case where the entire packaging container is made of a polymer film, and a case where a part of the packaging container such as the lid material is made of a polymer film. It is meant to include both.
Therefore, the packaging container may be a flexible packaging container in which all or a main part is made of a flexible polymer film, that is, a so-called packaging bag, and the flexible polymer film and the coated paper, etc. It may be a flexible packaging container in which other flexible members other than that are combined, or a packaging container in which a flexible polymer film and a rigid member are combined, for example, as a lid material. The molecular film may be combined with a rigid member such as a tray or a cup.

In an embodiment in which the packaging container is a so-called packaging bag, for example, two polymer films are superposed on each other, or one polymer film is folded, and three or two sides are heat-sealed. It is possible to form a packaging bag by fusing, for example. The remaining one side can be sealed by arranging the contents such as fruits and vegetables in the packaging bag and then similarly heat-sealing the contents.
The shape of such a packaging bag in a plan view may be a circle, a triangle, a quadrangle, or a polygonal shape of a quadrangle or more, but a rectangular shape is preferable from the viewpoint of workability and easy handling.

The packaging container used in the present invention comprises the above-described polymer film, and the oxygen permeability thereof is not particularly limited, but one having, for example, 4500 cc / m ² / day / atm or less is preferable. Is in the range of 500 cc / m ² / day / atm or more and less than 4500 cc / m ² / day / atm, more preferably in the range of 800 or more and 3500 cc / m ² / day / atm, and further preferably Can be used in the range of 900 or more and 2500 cc / m ² / day / atm, and can be stored for 72 hours under the condition of the amount and type of fruits and vegetables to be stored and the package sealed at 10 ° C. After that, an appropriate oxygen permeability can be selected according to the desired internal oxygen concentration and the like.

Fruits and vegetables The package of the present invention contains fruits and vegetables containing cabbage in the packaging container. Here, the term "includes" cabbage in the vegetables and fruits is meant to include both the case where all of the fruits and vegetables are made of cabbage and the case where some of the fruits and vegetables are made of cabbage. Therefore, the fruits and vegetables stored in the packaging container may or may not contain vegetables, fruits, etc. other than cabbage. Furthermore, as long as cabbage is contained, it may contain components other than fruits and vegetables, for example, foods other than fruits and vegetables, seasonings, food additives and the like.

The “cabbage” that constitutes the package of the present invention (stored in a packaging container) is a concept that includes general headed vegetables belonging to the Brassicaceae family Brassicaceae, and is limited to vegetables distributed under the name “cabbage” itself. Not done.
That is, the "cabbage" referred to here is, as preferable examples, cold (winter) cabbage, spring cabbage, plateau cabbage, red cabbage, green ball (round ball), savoy cabbage (crepe cabbage), brussels sprouts, petit vert, It is a concept that includes all of Misaki Kansai / Tongari Kabetsu, but is not limited to these.

  In the present invention, fruits and vegetables other than cabbage that can be stored together with cabbage are not particularly limited in the packaging container, and non-heated or heated fruits and vegetables that can be edible with cabbage can be stored appropriately. Specific examples of such fruits and vegetables include banana, mango, plum, apple, strawberry, mandarin orange, grape, Japanese pear, fruits such as pear, Japanese radish, carrot, potato, root vegetables such as burdock, tomato, Fruit vegetables such as cucumber, eggplant, peppers, edamame, okra, mung bean sprouts, soybean bean sprouts, sprouts such as tokyo, mushrooms such as shiitake, shimeji mushrooms, eringi, maitake, matsutake mushrooms, broccoli Examples include, but are not limited to, leafy vegetables such as spinach, spinach, komatsuna, bok choy, lettuce, asparagus, flowers or seedlings. From the effect of the present embodiment of controlling and maintaining the oxygen concentration, it is particularly effective in maintaining the freshness of fruits and vegetables in a form of substantially breathing.

In the present invention, there is no particular limitation on the form of fruits and vegetables containing cabbage stored in a packaging container and kept fresh. Therefore, fruits and vegetables containing cabbage may be as-harvested, may be so-called pretreated with outer leaves removed, or may be so-called cut vegetables (cut cabbage) that have been cut. May be. The fruits and vegetables may be those that have undergone any or all of the treatments such as washing, cooling, dehydration, and those that do not undergo any of these treatments.
In the case of cut cabbage that is stored and kept fresh, it is preferable that the cabbage is cut, washed, dehydrated and / or dried to be adjusted to an appropriate water content. More specifically, for example, the cut cabbage is washed at 80 to 120 ppm for 10 to 20 minutes with hypochlorous acid based on the "Massive Cooking Facility Hygiene Management Manual" (Ministry of Health and Welfare) and then "Analysis of nutrition labeling etc. according to nutrition labeling standards." Based on the "Method" (Consumer Affairs Agency), the amount of water measured based on the weight loss when dried under reduced pressure at 70 ° C for 5 hours should be within the range of 10 to 20% in order to prevent odor generation and browning. It is particularly preferable from the viewpoint of the balance of prevention of deterioration of appearance.

  Demand for cut vegetables has been increasing in recent years because they can be easily served for meals, and has high economic value. Cut cabbage is a typical cut vegetable, and can be easily served as a salad or the like without any treatment, and thus has a particularly high economic value. On the other hand, when vegetables, particularly cabbage, are cut, the respiratory action and metabolic reaction are rapidly activated, and the quality tends to be rapidly reduced. Since the present embodiment can be effectively used to maintain the freshness of such cut cabbage, it has a particularly high economic value.

  Depending on the type and form of the cabbage (and fruits and vegetables stored with the cabbage, if present), the oxygen concentration that is preferable for maintaining freshness will vary to some extent within the scope of the present invention. Although the aspect of the polymer film that imparts the transparency is also different, by appropriately setting these, the present invention effectively retains the freshness of any of the above cabbage (and fruits and vegetables stored with the cabbage, if present). It can be performed.

Package The internal oxygen concentration of the package of the present invention after the package is sealed and kept at 10 ° C. for 72 hours is 1.5% by volume or less.
The internal oxygen concentration after keeping the package at 10 ° C. for 72 hours for 72 hours is 1.5 vol% or less, so that cabbage browning and off-flavors, especially browning in the fruits and vegetables contained in the packaging container, It can be suppressed for a long period of time, exceeding the limit of the conventional technology. In a preferred embodiment of the package of the present invention, browning and off-flavor of fruits and vegetables containing cabbage can be suppressed for 72 hours or more under the condition of 10 ° C after sealing the package. In the embodiment, the browning of fruits and vegetables containing cabbage is more preferably suppressed for 96 hours or longer under the condition of 10 ° C., further preferably suppressed for 120 hours or longer, and further suppressed for 144 hours or longer. Particularly preferred. Furthermore, in the embodiment, it is more preferable to suppress the generation of offensive odor from fruits and vegetables containing cabbage for 96 hours or longer under the condition of 10 ° C., further preferably to suppress it for 120 hours or longer, and for 144 hours or longer. It is particularly preferable to suppress.
The internal oxygen concentration of the package of the present invention after holding at 10 ° C. for 72 hours after sealing the package is particularly preferably 1.2% by volume or less.
There is no particular lower limit to the internal oxygen concentration of the package of the present invention after the package is kept at 10 ° C. for 72 hours after sealing, but from the viewpoint of more effectively suppressing odor, it is 0.01. It is preferably at least vol%, particularly preferably at least 0.02 vol%.

The oxygen concentration inside the package can be specified, for example, by sampling the gas inside the package with a sampling needle tube and measuring the oxygen concentration with a zirconia oxygen concentration meter for food packaging.
Here, "after sealing the package" means the elapsed time when the fruits and vegetables containing cabbage are stored in the packaging container and then the packaging container is sealed and held at a predetermined temperature. After holding for 72 hours at 10 ° C. after sealing, means the state immediately after storing fruits and vegetables containing cabbage in the packaging container and sealing the packaging container and then holding for 72 hours at 10 ° C.

In the package of the present invention, oxygen is consumed as the fruits and vegetables containing the stored cabbage breathe, so that the change over time in the internal oxygen concentration is often suppressed to some extent. Therefore, in the present invention in which the internal oxygen concentration after holding the package at 10 ° C. for 72 hours is 1.5% by volume or less, the internal oxygen concentration is from the early stage to 72 hours after the package is sealed. Is 1.5% by volume or less. Such a history of oxygen concentration is particularly preferable for suppressing browning of fruits and vegetables containing cabbage for a long period of time.
Regarding the history of oxygen concentration, the oxygen concentration in the packaging container was 23% by volume or less immediately after the packaging was sealed, that is, immediately after the fruits and vegetables containing cabbage were stored in the packaging container and then the packaging container was sealed. Preferably. For example, by containing a gas or nitrogen containing a predetermined amount of oxygen or less in a packaging container together with fruits and vegetables containing cabbage and sealing the packaging container, browning of cabbage or the like can be suppressed particularly effectively for a long period of time. You can
The oxygen concentration in the packaging container immediately after sealing the package is more preferably 22% by volume or less.

  From the viewpoint of achieving the desired internal oxygen concentration described above, it is preferable that nitrogen is further enclosed in the packaging container. This is because by enclosing nitrogen in the packaging container, the internal oxygen concentration immediately after packaging can be kept low. Further, by further enclosing nitrogen, it becomes possible to keep the pressure inside the packaging container high, prevent the inflow of outside air with a higher oxygen concentration, and after sealing the package for 72 hours under the condition of 10 ° C, etc. The internal oxygen concentration can be kept low after a lapse of a predetermined time.

Polymer Film Further , in order to realize the above-mentioned desired internal oxygen concentration, it is desirable to configure the packaging container using a polymer film having an oxygen permeability of a predetermined value or less.
That is, the oxygen permeability of the polymer film used in the present invention is preferably 4500 cc / m ² / atm / day or less at 20 ° C. and 90% RH. When the oxygen permeability at 20 ° C. and 90% RH is the above value or less, oxygen is prevented from entering from the outside air, and even after 72 hours have passed under the condition of 10 ° C. after sealing the package, 1.5 A low internal oxygen concentration of less than or equal to volume% can be maintained, and browning of fruits and vegetables can be effectively suppressed. The oxygen permeability of the polymer film used in the present invention is preferably less than 4500 cc / m ² / atm / day at 20 ° C. and 90% RH, and more preferably 3500 cc / m ² / atm / day or less. More preferably, it is 2500 cc / m ² / atm / day or less, and particularly preferably.
There is no particular lower limit to the oxygen permeability of the polymer film, but as long as an ordinary polymer film not subjected to gas barrier coating or the like is used, at 20 ° C. and 90% RH, 500 cc / m ² / atm / day. Generally, the above is the case.
Further, from the viewpoint of more effectively preventing the generation of odor from the stored fruits and vegetables, it is preferable that the polymer film has an oxygen permeability that allows the fruits and vegetables to breathe. From this viewpoint, the oxygen permeability of the polymer film at 20 ° C. and 90% RH is preferably 800 cc / m ² / atm / day or more, and is 950 cc / m ² / atm / day or more. Particularly preferred.

The oxygen permeability of the polymer film used in the present invention can be measured, for example, by the following method.
First, a bag having an inner size of a (cm) x b (cm) is formed by the following method.
Fold one film into two almost evenly and set the scale of heating conditions to 3 with an impulse sealer (Fuji Impulse Co., Ltd., product number Fi-200-10WK) with a width of about 5 mm, and heat seal the film. Heat seal one entire side that is substantially perpendicular to the heat-sealed side so that the side is almost in the center, and the entire side excluding about 2 cm of one end of the other side, which is the communicating portion, and then the inside dimension a ( A bag of (cm) x b (cm) is formed.
Next, nitrogen gas is injected from the communication section, and when the inside of the bag becomes saturated, almost all the gas in the bag is discharged from the communication section. After repeating this operation 5 times, nitrogen gas is injected to saturate the inside of the bag with nitrogen gas, and the communication part is heat-sealed under the same conditions with the impulse sealer. The bag saturated with nitrogen gas is left for 6 hours in a room at 22 ° C. and 40% relative humidity in air (1 atm, oxygen concentration: 21%, nitrogen concentration: 79%).
Next, about 20 cc is sampled with a sampling needle tube, and the oxygen concentration in the bag is measured by a zirconia oxygen concentration meter for food packaging (Model LC-750F, manufactured by Toray Engineering Co., Ltd.). Further, the volume of gas in the bag is measured, and the oxygen permeability is calculated from the following formula.
(Equation) Oxygen permeability = internal oxygen concentration change (%) / 100 × volume (cm ³ ) × 24 × 60 / hour (360 minutes) × 10000 cm ² / area (2 × a × bcm ² ) /0.21 ( Partial pressure of oxygen)

By appropriately selecting the material, thickness, processing method, etc. of the polymer film, the oxygen permeability of the polymer film can be appropriately adjusted. For example, in the case of a biaxially oriented polypropylene (OPP) film, by setting the thickness to 10 μm or more, the oxygen permeability at 20 ° C. and 90% RH can be 4500 cc / m ² / atm / day or less. Therefore, it is preferable. Considering mechanical strength, processability, etc., the thickness of the polymer film is more preferably 15 to 45 μm, and particularly preferably 20 to 40 μm.

As described above, the oxygen permeability of the polymer film can be adjusted by appropriately selecting the material of the polymer film, the thickness, the processing method, etc., so that it is not always necessary to adjust the oxygen permeability. It is not necessary to provide an opening in the polymer film. In particular, the oxygen permeability of 4500 cc / m ² / atm / day or less at 20 ° C. and 90% RH in the preferred embodiment of the present invention can be realized without providing an opening in the polymer film.
Since there is no need to provide openings in the polymer film, the manufacturing process is simpler and less expensive, and it is not necessary to precisely control the size, shape, etc. of the openings, and also in terms of mechanical strength. It is advantageous.
The absence of openings in the polymer film can be confirmed, for example, by the polymer film forming the packaging container having no through holes that can be confirmed by an ink leak checker.

On the other hand, in one embodiment of the present invention, when it is necessary to use a thick polymer film or a polymer material having low oxygen permeability, it is desirable from the viewpoint of maintaining the minimum respiration of fruits and vegetables. In order to realize the above oxygen permeability, the openings provided in the polymer film may be used together. The shape of the opening is not particularly limited, and may be circular, substantially circular, or slit-shaped. A circular or substantially circular opening is preferable because it is easy to process, and a slit-shaped opening is preferable because it can effectively prevent foreign matter from entering.
As a method for providing the fine holes, both physical means such as a heating needle and optical means such as a laser can be used. A pore size of 100 to 300 μm is a range in which the pores can be sufficiently opened even by using a physical means, which is advantageous in terms of cost. Of course, the holes can be opened with a laser or the like, and in this case, the hole diameter can be controlled more precisely. In the present invention, when a laser is used for micropore opening, it is preferable that the target film efficiently absorbs laser light. For example, a carbon dioxide laser, a YAG laser, a helium neon laser, an excimer laser, a UV laser light oscillator, and a semiconductor laser light oscillator can be used, but the invention is not particularly limited thereto.
Further, laser hole processing preferably used in the production of the package of the present invention is different from slit processing, since there is no physical contact with metal, there is no fear of mixing of a missing blade, needle, etc., and the opening area is in the slit. Compared to the above, it is preferable because quality control (control of gas permeability) is easy because it is constant.
The size of each opening and the number of openings can be appropriately set and changed as long as the oxygen permeability of the polymer film is appropriate, and in that case, the openings occupying the effective area of the polymer film. The number of is a guideline. For example, it is a slit-shaped opening having a length of 2 mm, and in the closed state, the width as the through-hole cannot be visually observed by observation with an optical microscope (manufactured by Olympus, model SZH-131) at a magnification of 4 times. In the case of providing an object, there is an effect of increasing the oxygen permeability of about 1000 cc / m ² / atm / day for each opening of a 200 mm × 200 mm packaging container, and it is necessary based on such knowledge. It is preferable to determine the number of slit openings from the oxygen permeability of the entire packaging container.
As the laser processing, it is preferable to provide about 1 to 5 holes having a diameter of 50 to 200 μm, and the openings can be visually recognized by observation with an optical microscope (manufactured by Olympus, model SZH-131) at a magnification of 4 times. ..

  There is no particular limitation on the thickness of the polymer film used in this embodiment, suitable oxygen permeability, flexibility when forming a packaging container, strength, transparency, economic efficiency, accuracy in forming the opening and From the viewpoint of ease and the like, a suitable thickness may be appropriately selected in relation to the material forming the polymer film. Typically, the thickness of the polymer film is preferably 10 to 120 μm, more preferably 15 to 50 μm, and particularly preferably 20 to 40 μm.

  The material of the polymer film is not particularly limited, but the polymer used in the conventional film for packaging fruits and vegetables can be appropriately used. Examples thereof include polyethylene, polypropylene, polyethylene terephthalate, polystyrene, nylon (polyamide), ethylene vinyl acetate copolymer (EVA), polybutylene succinate, polybutylene succinate adipate, and polylactic acid. Further, for example, a natural polymer such as cellophane can be used. Furthermore, any of these materials may be used alone, or a plurality of these materials may be blended and / or laminated.

  From the viewpoint of easiness of processing and cost, the material of the polymer film is preferably a thermoplastic resin. Examples of the thermoplastic resin include homopolymers or copolymers of α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene. Specifically, high-pressure low density polyethylene, linear low density polyethylene (LLDPE), high density polyethylene and other ethylene polymers, propylene homopolymers, propylene / α-olefin random copolymers, propylene block copolymers. And a polyolefin such as poly-1-butene and poly-4-methyl / 1-pentene. Examples of the thermoplastic resin include polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyamides such as nylon-6, nylon-66, polymetaxylene adipamide, polyvinyl chloride, polyimide, ethylene acetic acid. Examples thereof include vinyl copolymers or saponified products thereof, polyvinyl alcohol, polyacrylonitrile, polycarbonate, polystyrene, ionomers, biodegradable resins such as polylactic acid and polybutylene succinate, and mixtures thereof. These thermoplastic resins may be used alone or in combination of two or more. Among these, as the thermoplastic resin, polyolefin, polyester, polyamide and the like are preferable because they have excellent rigidity and transparency. As the thermoplastic resin, ethylene-based polymers and propylene-based polymers are more preferable because they are lightweight and have excellent film processability, and propylene-based polymers are more preferable from the viewpoint of flexibility and transparency.

<Propylene polymer>
As the propylene-based polymer, propylene homopolymer (also referred to as homo PP), which is manufactured and sold under the name of polypropylene, propylene / α-olefin random copolymer (also referred to as random PP). , A propylene-based crystalline polymer such as a mixture of propylene homopolymer and low crystalline or amorphous propylene / ethylene random copolymer (also called block PP). .. The propylene-based polymer may be a mixture of propylene homopolymers having different molecular weights, and includes a propylene homopolymer and a random copolymer of propylene and ethylene or an α-olefin having 4 to 10 carbon atoms. It may be a mixture.

  Specific examples of the propylene-based polymer include polypropylene, propylene / ethylene copolymer, propylene / ethylene / 1-butene copolymer, propylene / 1-butene copolymer, propylene / 1-pentene copolymer. , A propylene / 1-hexene copolymer, a propylene / 1-octene copolymer, etc. as a main monomer, and a copolymerization of this with at least one selected from ethylene and α-olefins having 4 to 10 carbon atoms. An example is coalescence. These may be used alone or in combination of two or more.

The density of the propylene-based polymer is preferably 0.890 to 0.930 g / cm ³ , and more preferably 0.900 to 0.920 g / cm ³ . The MFR (ASTM D1238 load 2160 g, temperature 230 ° C.) of the propylene-based polymer is preferably 0.5 to 60 g / 10 minutes, more preferably 0.5 to 10 g / 10 minutes, and even more preferably 1 to 5 g / 10 minutes. Is more preferable.

<Ethylene polymer>
As the ethylene-based polymer, a homopolymer of ethylene, a copolymer containing ethylene as a main monomer, and a copolymer thereof with at least one or more α-olefins having 3 to 8 carbon atoms, an ethylene / vinyl acetate copolymer, Examples include saponified products and ionomers. Specifically, polyethylene, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / 1-pentene copolymer, ethylene / 1-hexene copolymer, ethylene-4-methyl-1-pentene Examples of the copolymer include a copolymer, ethylene / 1-octene copolymer, and the like, which has ethylene as a main monomer, and at least one α-olefin having 3 to 8 carbon atoms. The proportion of α-olefin in these copolymers is preferably 1 to 15 mol%.

  Examples of the ethylene-based polymer include ethylene polymers manufactured and sold under the name of polyethylene. Specifically, high-pressure low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE) are preferable, and LLDPE is more preferable. LLDPE is a copolymer of ethylene and a small amount of propylene, butene-1, heptene-1, hexene-1, octene-1, 4-methyl-pentene-1 and the like. The ethylene-based polymer may be a homopolymer of ethylene or a polymer mainly composed of ethylene such as LLDPE.

Density of the ethylene polymer is preferably ^{0.910~0.940g / cm 3, 0.920~0.930g / cm} 3 is more preferable. When the density is 0.910 g / cm ³ or more, heat sealability is improved. Further, when the density is 0.940 g / cm ³ or less, workability and transparency are improved.

  The blend and / or the laminate may be a blend and / or a laminate of any one of the above-mentioned polymers, and any one of the above-mentioned polymers and a material other than the polymer may be used. May be a blend and / or a laminate. That is, a polymer film is a material other than a polymer, for example, a heat stabilizer (antioxidant), a weather stabilizer, an ultraviolet absorber, a lubricant, a slip agent, a nucleating agent, an antiblocking agent, an antistatic agent, an antifogging agent. In addition to pigments, dyes, etc., it may contain various fillers such as talc, silica, diatomaceous earth, etc., or may be a laminate of a polymer film and metal foil, paper, nonwoven fabric, etc.

In the present invention, the polymer film constituting the packaging container may be either a non-stretched film or a stretched film.
From the viewpoint of mechanical strength and the like, stretched films of various polymers can be preferably used.
In particular, a stretched film using a propylene-based polymer (stretched polypropylene film) is excellent in mechanical strength, transparency, heat resistance and the like, and therefore can be particularly preferably used in the packaging container used in the present invention.
Further, the film using the ethylene polymer (polyethylene film) may be either a non-stretched film or a stretched film, but from the viewpoint of heat sealability and the like, a non-stretched film is particularly preferably used. be able to.
Examples of particularly preferable polymer films constituting the packaging container in the present invention include a stretched polypropylene film, a polyethylene film, and a laminate of a stretched film and a polyethylene film.

<Stretched polypropylene film>
The stretched polypropylene film preferably used in the present invention may be composed of a film stretched in at least one direction, or the stretched polypropylene film itself may be stretched in at least one direction. When a biaxially stretched film is obtained as a stretched polypropylene film, it can be easily produced by, for example, sequential or simultaneous biaxial stretching. When a biaxially stretched film is obtained as a stretched polypropylene film, it is usually stretched 5 to 8 times in the longitudinal direction, and then 8 to 10 times in the transverse direction by using a tenter mechanism to obtain a final film thickness. 20 to 40 μm, or by stretching 5 to 10 times (25 to 100 times in area magnification) in the machine direction and the transverse direction, respectively.
<Polyethylene film>
The polyethylene film preferably used in the present invention is a film containing the ethylene polymer. Although various known molding methods can be used for the polyethylene film, cast molding by extrusion with an extruder is preferable from the viewpoint of production efficiency.

<Stretched film>
Polyamide film made of nylon 6, nylon 66, etc., film made of polyester typified by polyethylene terephthalate, polyethylene naphthalate, polycarbonate film, ethylene / vinyl alcohol copolymer film, polyvinyl alcohol film, polyvinyl chloride film, polyvinylidene chloride A uniaxially or biaxially stretched film comprising a film, a polystyrene film, a polyolefin such as polypropylene and poly L lactic acid, poly D lactic acid, or a stereocomplex polylactic acid in which poly L lactic acid and poly D lactic acid are precisely coordinated.

<Laminate of stretched film and polyethylene film>
The laminate of the stretched film and the polyethylene film preferably used in the present invention is obtained by laminating the layer of the polyethylene film and the layer of the stretched film. The polyethylene-based film may be stretched in one direction or in two directions, but it is preferably an unstretched film from the viewpoint of stability of mechanical strength of the packaging bag.
From the viewpoint of adhesion stability, dry lamination is performed in which a stretched film and a polyethylene-based film that are prepared in advance are attached with an adhesive, and the stretched film surface to which the adhesive is applied here is subjected to corona treatment. preferable. Specifically, the surface tension of the film surface after corona treatment is preferably 35 mN / m or more, and more preferably 40 mN / m or more, from the viewpoint of adhesion stability.

Further, these polymer films may be subjected to stretching processing, anti-fog processing or printing, and inorganic antibacterial agents such as silver and copper and organic antibacterial agents such as chitin, chitosan and allyl isothiocyanate. The agent may be applied, or these may be kneaded into the film.
From the viewpoint of maintaining the freshness of contents such as fruits and vegetables, the polymer film preferably contains at least one antibacterial agent.
Further, a specific surfactant may be present on the surface of the polymer film in a specific amount, or the polymer film may contain a specific surfactant in a specific amount to have an antibacterial function. For example, at least one compound selected from the group consisting of palmityldiethanolamine, stearyldiethanolamine, glycerin monolaurate and diglycerin monolaurate, is preferably present on at least one surface of the polymer film, at least It is particularly preferred that one compound is present in an amount of 0.002-0.5 g / m ² . Alternatively, the polymer film preferably contains at least one compound selected from the group consisting of palmityldiethanolamine, stearyldiethanolamine, glycerin monolaurate and glycerin monocaprate, and 0.001 to 3 parts by mass. It is particularly preferable to contain.
There is a specific amount of a specific surfactant on the surface of the polymer film, or the polymer film contains a specific amount of a specific surfactant, dew condensation on the surface of the polymer film is suppressed, bacteria By suppressing the reproduction of the bacteria, the growth of various bacteria in the dew condensation (drip) is suppressed and the antibacterial function is exerted.

From the viewpoint of transparency, flexibility, cost, etc., it is particularly preferable to use a stretched polypropylene film, which has been widely used in the related art, or a laminate of a stretched polypropylene film and a polyethylene-based film as a polymer film. .. Since these films are generally excellent in heat sealability, they have good productivity in the production of packaging containers.
In this case, when the stretched propylene film is used alone, the thickness thereof is preferably 10 to 100 μm, and when the laminate of the stretched polypropylene film and the polyethylene film is used, the former thickness is 10 to 50 μm. The latter preferably has a thickness of 10 to 120 μm.

  When a polymer film that is not necessarily suitable for heat sealing is used, it may be formed by laminating or coating a sealant layer on all or part of the polymer film. For example, a cellophane film coated with an acrylic resin, a film obtained by laminating linear low density polyethylene (LLDPE) polystyrene and EVA on polyethylene terephthalate (PET) can be used, and these can be used as suitable polymer films.

Method for producing package, and method for maintaining freshness A vegetable or fruit containing cabbage is stored in the packaging container of the present invention, and the internal oxygen concentration is appropriately adjusted, whereby the package of the present invention can be produced. The freshness preservation method for fruits and vegetables, which is one embodiment of the present invention, can be carried out.
Hereinafter, the method for producing a package of the present invention will be described by taking a package for keeping the freshness of cut cabbage as an example.

  First, in a pretreatment step, the outer leaf is manually removed, divided into 2 to 4 pieces, and the cabbage from which the core is removed is supplied to the conveyor. The cabbage transported by the conveyor is cut by a slicer, washed in a washing tank filled with cold water for cooling as well, and dehydrated by a centrifugal dehydrator or the like after draining. The dehydrated cut cabbage is packed in a packaging container (one side of which is not sealed) containing the polymer film used in the present embodiment, and after weighing, the packaging container is sealed to retain the freshness of the cut cabbage. A package is manufactured.

From the viewpoint of maintaining the freshness of the cut cabbage, it is preferable to use a blade with good sharpness and reduce scratches on the cut surface.
Further, the narrower the cut width, the larger the cutting area and the more difficult it becomes to maintain the freshness. Therefore, from the viewpoint of keeping the freshness, it is preferable that the cut width is wide as long as it meets the demand form.
Further, if a large amount of various bacteria adheres to the cut cabbage from the beginning, it becomes more difficult to maintain the freshness. Therefore, it is preferable to thoroughly clean the cut cabbage to reduce the adhesion of various bacteria as much as possible. Washing is particularly effective for maintaining freshness because it not only reduces the attachment of bacteria, but also has the effect of removing cell liquor containing highly active enzymes and the like that may cause discoloration and the like.
In addition, it is important for keeping the freshness to sufficiently remove the water adhering to the surface of the cut cabbage after washing. Even if water is drained by leaving still after washing, since much water still adheres to the surface of the cut cabbage in many cases, it is effective to remove water using a centrifugal dehydrator or the like.
This is because the growth of miscellaneous bacteria in the excessively adhered minute water droplets can be suppressed by adjusting the water content appropriately. More specifically, for example, based on the "Massive Cooking Facility Hygiene Management Manual" (Ministry of Health and Welfare), after "80-120ppm, 10-20 minutes of hypochlorous acid cleaning,""analysis method of nutrition labeling in the nutrition labeling standard" (consumer In order to control the odor and prevent the deterioration of appearance such as browning, it is necessary to set the amount of water in the range of 10 to 20% based on the weight loss when dried under reduced pressure at 70 ° C for 5 hours. Particularly preferred.

The package for freshness preservation of fruits and vegetables of the present embodiment may be filled with nitrogen and / or deaerated after storing fruits and vegetables containing cabbage and sealing the packaging container. By enclosing and / or degassing nitrogen, it is possible to quickly reach a desired oxygen concentration designed as an equilibrium state between the oxygen permeability of the packaging container and the respiration rate of fruits and vegetables, which is advantageous for maintaining freshness. ..
In addition, degassing may be performed after sealing the packaging container from the viewpoints of improving efficiency in the distribution process, saving space, and eliminating a specific gas.

According to the method as described above, preferably, vegetables and fruits containing cabbage are stored in a packaging container containing a polymer film having an oxygen permeability of 4500 cc / m ² / atm / day or less at 20 ° C. and 90% RH. After carrying out the step of, the freshness of fruits and vegetables including cabbage is preferably 72 under the condition of 10 ° C. by carrying out the step of setting the oxygen concentration immediately after sealing in the packaging container to 23% by volume or less. It can be effectively held for at least an hour, more preferably for at least 96 hours, further preferably for at least 120 hours, particularly preferably for at least 144 hours.

In the package of the present invention, only fruits and vegetables containing cabbage may be stored in the packaging container, and further other members may be stored.
For example, in addition to fruits and vegetables, a hygroscopic agent and / or an antibacterial agent may be contained in the packaging container.
The hygroscopic agent is not particularly limited, and known or commercially available materials having a hygroscopic effect or a humidity adjusting effect can be used. Suitable examples of the hygroscopic agent include, for example, activated carbon, silica gel, alumina gel, silica alumina gel, anhydrous magnesium sulfate, zeolite, synthetic zeolite, calcium oxide, calcium chloride, and burnt alum, or a mixture thereof. Examples include, but are not limited to:
Among these, it is particularly preferable to use activated carbon, which has relatively little concern about influence on fruits and vegetables and use near fruits and vegetables which are foods. The activated carbon may be powdery or granular, and the raw material may be coconut shell, sawdust, charcoal, bamboo charcoal, lignite, peat, rice, petroleum pitch, or any other material. It is desirable that the activated carbon be packed in a unit such as non-woven fabric, cellophane, paper or the like, but the activated carbon itself may be in a fibrous form. As the wrapping material for the activated carbon, it is preferable to use one having a heat-sealing property, such as a non-woven fabric made of synthetic resin, but as long as it has water vapor permeability and the activated carbon does not spill, it may be paper, natural fiber, etc. no problem.

  There is no particular limitation on the antibacterial agent, and substances having an antibacterial effect can be appropriately used, but there is relatively little concern about the effects on fruits and vegetables including cabbage and the use near foods such as fruits and vegetables. An antibacterial agent can be preferably used. More specifically, natural antibacterial agents such as chitosan, allyl isothiocyanate, hinokitiol, limonene can be stored in the packaging container.

  Hereinafter, the present invention will be specifically described with reference to Examples / Comparative Examples. The present invention is not limited to the following examples in any sense.

In the following examples / comparative examples, evaluation of each characteristic was performed by the following methods.
(Aperture)
After injecting a red penetrant (product name: AGELESS SEAL CHECK SPRAY, manufactured by Mitsubishi Gas Chemical Co., Inc.) into the packaging container, set the heating condition scale to 3 with an impulse sealer, heat seal with a width of about 5 mm, and paper. (Kokuyo PPC paper, common paper A4) was pressed, and presence / absence of openings and the number thereof were confirmed by the presence / absence of ink transfer to the paper. When the openings were observed, the size and shape of the openings were also observed with an optical microscope.
(Oxygen permeability)
First, a bag having an inner size of 220 mm × 240 mm was formed by the following method.
Fold one film into two almost evenly and set the scale of heating conditions to 3 with an impulse sealer (Fuji Impulse Co., Ltd., product number Fi-200-10WK) with a width of about 5 mm, and heat seal the film. Heat-seal so that the side is almost in the center, and one side that is almost perpendicular to the heat-sealing side is heat-sealed, except for the end of about 2 cm that is the communicating part of the other side, and the inside dimension is 220 mm × A 240 mm bag was formed.
Next, nitrogen gas was injected from the communication part, and after the bag was saturated, almost all the gas in the bag was discharged from the communication part. After repeating this operation 5 times, nitrogen gas was injected to saturate the inside of the bag with nitrogen gas, and the communication part was heat-sealed under the same conditions with the impulse sealer. The bag saturated with nitrogen gas was left to stand in a room at 22 ° C. and 40% relative humidity in air (1 atm, oxygen concentration: 21%, nitrogen concentration: 79%) for 6 hours.
Next, about 20 cc of gas in the bag was sampled with a sampling needle tube, and the oxygen concentration in the bag was measured with a zirconia oxygen concentration meter for food packaging (Toray Engineering Co., Ltd., model number LC-750F). Further, the volume of gas in the bag was measured, and the oxygen permeability was calculated from the following formula.
(Formula) Oxygen permeability = Internal oxygen concentration change (%) / 100 × Volume (cm ³ ) × 24 × 60 / hour (360 minutes) × 10000 cm ² / Area (1232 cm ² ) /0.21 (partial pressure of oxygen )
(Oxygen concentration, carbon dioxide concentration)
The measurement was performed using an O ₂ / CO ₂ analyzer Check Mate 3 for food packaging manufactured by Dansensor.
(appearance)
The package was unsealed, the fruits and vegetables taken out were lined up, and the area of the entire browning part was visually evaluated with n = 3 centering on the cabbage cross section.
The evaluation criteria are as follows.
A: No browning and no problem B: Browning but 10% or less of the entire cross section is slightly visible C: Browning is 30% or less of the entire cross section, which is quite noticeable but can be sold D: Browning However, it is 50% or less of the entire cross section, and it is significantly conspicuous and unsellable by consumers. E: Browning is large and it is clearly unsellable by consumers. In addition, the presence or absence of mold was also observed.
(smell)
When the seal of the package was opened, the face was brought close to the package and the internal odor was smelled to perform a sensory evaluation with n = 3.
The evaluation criteria are as follows.
A: There is no problem in the fresh state, or there is a slight odor but it can be said that it is fresh. B: It has a strong odor but is in the same state as that on the market, and it is in a state where it can be sold. State D: A state in which the odor is stronger and the product cannot be sold

(Example 1)
Two 30 μm-thick OPP (biaxially oriented polypropylene) films are superposed, three sides are sealed with heat seal and cut, and one side is an unsealed packaging bag (220 mm × 240 mm, inside size). Area: 1232 cm ² ) was prepared.
150 g of cut cabbage that had been washed with 100 ppm of hypochlorous acid for 10 minutes was enclosed in a packaging container, filled with nitrogen, and then heat-sealed to produce a package. The package was stored at 10 ° C, and after 0, 24, 48, 72, 96, 120, and 144 hours, the internal oxygen concentration and the carbon dioxide concentration were measured to evaluate the appearance and odor of the cut cabbage.
The oxygen transmission rate of the film was 1000 CC / m ² / atm / day.
The results are shown in Table 1.

(Example 2)
A package was prepared and evaluated in the same manner as in Example 1 except that an OPP (biaxially oriented polypropylene) film was provided with one hole having a diameter of 100 μm by laser processing.
The oxygen transmission rate of the film was 2000 CC / m ² / atm / day.
The results are shown in Table 1.

(Comparative Example 1)
A package was prepared and evaluated in the same manner as in Example 1 except that a polyethylene film having a thickness of 30 μm was used instead of the OPP (biaxially oriented polypropylene) film.
Observation of the presence or absence of an opening in the film confirmed that there was no opening. The oxygen transmission rate of the film was 5000 CC / m ² / atm / day.
The results are shown in Table 1.

(Comparative example 2)
A package was prepared and evaluated in the same manner as in Example 1 except that one needle hole having a diameter of 300 μm was provided in the OPP (biaxially oriented polypropylene) film.
The oxygen transmission rate of the film was 10,000 CC / m ² / atm / day.
The results are shown in Table 1.

(Comparative example 3)
A package was prepared and evaluated in the same manner as in Example 1 except that three needle holes each having a diameter of 300 μm were provided in the OPP (biaxially oriented polypropylene) film.
The oxygen transmission rate of the film was 15000 CC / m ² / atm / day.
The results are shown in Table 1.

(Comparative example 4)
A package was prepared and evaluated in the same manner as in Example 1 except that 10 needle holes each having a diameter of 300 μm were provided in an OPP (biaxially oriented polypropylene) film.
The oxygen transmission rate of the film was 30,000 CC / m ² / atm / day.
The results are shown in Table 1.

(Example 3)
A package was prepared and evaluated in the same manner as in Example 2 except that a mixed gas of oxygen: 5% by volume / nitrogen: 95% by volume was filled in place of the nitrogen gas.
The results are shown in Table 1.

(Example 4)
A package was prepared and evaluated in the same manner as in Example 2, except that a mixed gas of oxygen: 10% by volume / nitrogen: 90% by volume was filled in place of the nitrogen gas.
The results are shown in Table 1.

(Example 5)
A package was prepared and evaluated in the same manner as in Example 2 except that a mixed gas of oxygen: 15% by volume / nitrogen: 85% by volume was filled in place of the nitrogen gas.
The results are shown in Table 1.

In each of the examples in which the oxygen concentration inside the package after holding the package at 10 ° C. for 72 hours was 1.5% by volume or less, for a long period of 72 hours after the package was sealed, It was possible to suppress browning and off-flavor of cut cabbage. The browning could be prevented from occurring for a long period of 144 hours after sealing the package.
On the other hand, in each of the comparative examples that did not satisfy the above conditions for the oxygen concentration, browning occurred in the appearance, and the commercial value of the cut cabbage was partially impaired. In addition, mold was generated in each comparative example, and the commercial value of the cut cabbage was significantly impaired.

  The packaging of the present invention has a proper internal oxygen concentration of the packaging after a predetermined time has passed, and thus browning and off-flavor of fruits and vegetables, including cabbage such as cut cabbage, having a high economic value, especially browning Since it can be suppressed for an extremely long period of time, it has high practical value and has high availability in various fields of industry such as food processing, distribution, and restaurant.

Claims (8)

Fused polypropylene film, polyethylene-based film, or two polymer films that are a laminate of a stretched film and a polyethylene-based film stacked on top of each other, or fused in a state of folding one polymer film. and it houses the fruit or vegetable comprising a cut cabbage packaging container comprising, inner oxygen concentration in after holding for 72 hours at 10 ° C. after the sealing of the package is 0.01% by volume or more, 1.04% or less by volume The package.   The package according to claim 1, wherein nitrogen is further enclosed in the packaging container. The package according to claim 1, wherein the oxygen permeability of the polymer film at 20 ° C. and 90% RH is 500 cc / m ² / atm / day or more and 2500 cc / m ² / atm / day or less.   The package according to any one of claims 1 to 3, wherein the polymer film has a thickness of 15 to 45 µm.   The package according to any one of claims 1 to 4, wherein the polymer film contains at least one antibacterial agent or is coated with at least one antibacterial agent.   The package according to any one of claims 1 to 5, further containing a hygroscopic agent and / or an antibacterial agent. The oxygen permeability at 20 ° C. and 90% RH is 500 cc / m ² / atm / day or more and 2500 cc / m ² / atm / day or less, and a stretched polypropylene film, a polyethylene film, or a laminate of a stretched film and a polyethylene film. Two vegetables, which are the body, are stacked on top of each other, or one polymer film is folded, and the fruits and vegetables containing the cut cabbage are stored and sealed in a packaging container that is fused together. And a step of adjusting the oxygen concentration in the packaging container immediately after sealing to 0 vol% or more and 15 vol% or less.   The method for maintaining freshness of fruits and vegetables according to claim 7, further comprising the step of enclosing nitrogen in the packaging container.