JP2020068726A - Method for evaluating packaging container for keeping freshness of fruits and vegetables, package for keeping freshness of fruits and vegetables, and method for manufacturing the same - Google Patents

Abstract

To provide a method for evaluating a packaging container for keeping freshness of fruits and vegetables in which a packaging container that can suppress proliferation of bacteria represented by coliform bacillus extremely effectively can be discriminated.SOLUTION: A method for evaluating a packaging container for keeping freshness of fruits and vegetables has: a process of inoculating a predetermined amount A1 of bacteria on fruits and vegetables 1; a process of housing the fruits and vegetables 1 into a packaging container containing carbonic acid gas and sealing the packaging container; a process of storing the packaging container at predetermined storage temperature for a predetermined time; and a process of taking out the fruits and vegetables 1 from the packaging container, measuring the number A2 of the bacteria on the fruits and vegetables 1, and determining one having ratio A2/A1 with a predetermined value or less as non-defective.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a method for evaluating the freshness retention performance of a packaging container, a package for freshness preservation of fruits and vegetables using the method, and a method for producing the same.
Since the packaging body can effectively suppress the growth of various bacteria such as Escherichia coli, it is suitable for keeping the freshness of fruits and vegetables stored in the packaging container, and particularly suitable for keeping the freshness of cut vegetables and the like. Is.

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.

By the way, a method using an agar medium or the like is generally adopted as a method for evaluating the freshness retention performance. According to the studies by the present inventors, since the environment is different in the medium, there were cases in which sufficient accuracy could not always be obtained in order to evaluate the actual growth of bacteria on vegetables.
From such a viewpoint, there has been a demand for an evaluation method capable of highly accurately determining a packaging container capable of stably suppressing the growth of various bacteria.

JP-A-5-168400

  In view of the limitations of the above-mentioned conventional techniques, the present invention can identify with high accuracy a packaging container that can stably and effectively suppress the growth of various bacteria such as Escherichia coli, and a packaging container for maintaining freshness of fruits and vegetables. It is an issue to provide an evaluation method of.

The present inventors, as a result of diligent studies, inoculate a predetermined amount of bacteria on fruits and vegetables, and seal the packaging container by storing the fruits and vegetables in a packaging container for freshness maintenance of the fruits and vegetables to be evaluated, The present invention found that the quality of the packaging container can be evaluated easily and highly accurately by measuring the number of the bacteria on the fruits and vegetables after holding the packaging container at a predetermined storage temperature for a predetermined time. Has been completed.
That is, the present invention is
[1]
A method of evaluating a packaging container for keeping freshness of fruits and vegetables,
A step of inoculating a predetermined amount of A1 bacteria on the fruits and vegetables 1,
Storing the fruits and vegetables 1 in a packaging container containing carbon dioxide, and sealing the packaging container,
A step of storing the packaging container at a prescribed storage temperature for a prescribed time, and taking out the fruits and vegetables 1 from the packaging container, measuring the number A2 of the bacteria on the fruits and vegetables 1, and determining that the ratio A2 / A1 is not more than a prescribed value. Process to judge as good product,
Is an evaluation method.
[1]

Hereinafter, each of [2] to [9] is one aspect or a preferred embodiment of the present invention.
[2]
The fruits and vegetables 1 are lettuce, cabbage, radish, carrot, potato, burdock, tomato, cucumber, eggplant, peppers, edamame, okra, mung bean sprouts, soybean sprouts, pearl millet, shiitake mushrooms, shimeji mushrooms, eringi, maitake mushrooms, matsutake mushrooms, broccoli, spinach. The evaluation method according to [1], wherein the evaluation method is at least one selected from the group consisting of, Komatsuna, bok choy, asparagus, banana, mango, plum, apple, strawberry, mandarin orange, grape, Japanese pear, and pear.
[3]
At least one selected from the group consisting of Escherichia coli, Bacillus cereus, Listeria monocytogenes, pathogenic Escherichia coli 0-157, Salmonella, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Vibrio, black mold, and blue mold. The evaluation method according to [1] or [2], which is a seed.
[4]
A step of preparing a packaging container containing a polymer film,
Evaluating the packaging container by the evaluation method according to any one of [1] to [3],
A step of storing and sealing the fruits and vegetables 2 in a packaging container determined to be non-defective in the evaluation step,
And a method for producing a package for keeping freshness of fruits and vegetables.
[5]
A step of preparing a packaging container containing a polymer film,
Evaluating the packaging container by the evaluation method according to any one of [1] to [3],
A step of storing and sealing the fruits and vegetables 2 in a packaging container obtained in the same lot as the packaging container determined to be non-defective in the evaluation step,
And a method for producing a package for keeping freshness of fruits and vegetables.
[6]
Vegetables 1 and 2 are both lettuce or both are cabbage,
The inoculum A1 of the bacterium is not more than × 10 ⁷
The holding temperature of the packaging container is 25 ° C., the holding time is 24 hours,
[4] A method for producing a package for keeping freshness of fruits and vegetables according to [5].
[7]
A step of inoculating a predetermined amount of A1 bacteria on the fruits and vegetables 1,
Storing the fruits and vegetables 1 in a packaging container under an air atmosphere and sealing the packaging container,
The fungus after storage in air measured by a step of storing the packaging container at a predetermined storage temperature for a predetermined time, and a step of taking out the fruits and vegetables 1 from the packaging container and measuring the number B2 of the bacteria on the fruits and vegetables 1. The method for producing a package for keeping freshness of fruits and vegetables according to [6], which is determined as a non-defective product when the ratio (B2 / A2) of the number A2 of the bacteria to the number A2 of the bacteria is 6 or less.
[8]
A packaging body in which the fruits and vegetables 1 are housed and sealed in a packaging container determined to be non-defective by the method according to any one of [1] to [3].
[9]
The package according to [8], wherein the internal carbon dioxide concentration is 8% or more and 60% or less in volume%.

  According to the present invention, a packaging container for keeping freshness of fruits and vegetables capable of stably and effectively suppressing the growth of various bacteria such as Escherichia coli can be identified easily and with high accuracy. According to the method for producing a package for keeping freshness of fruits and vegetables using the same, and the package for keeping freshness of fruits and vegetables, it is possible to effectively suppress the growth of fungi on fruits and vegetables such as cut vegetables stored in the package. Therefore, it is possible to maintain the hygiene and safety of fruits and vegetables, and to effectively prevent the deterioration of appearance and the generation of offensive odor.

Hereinafter, modes for carrying out the present invention will be described.
The present invention is a method for evaluating a packaging container for maintaining freshness of fruits and vegetables,
A step of inoculating a predetermined amount of A1 bacteria on the fruits and vegetables 1,
Storing the fruits and vegetables 1 in a packaging container containing carbon dioxide and sealing the packaging container;
A step of holding the packaging container at a predetermined storage temperature for a predetermined time, and taking out the fruits and vegetables 1 from the packaging container, measuring the number A2 of the bacteria on the fruits and vegetables 1, and determining the ratio A2 / A1 is not more than a predetermined value. Process to judge as good product,
It is an evaluation method having.

Step of inoculating a predetermined amount A1 of bacteria on the fruits and vegetables 1 In the method for evaluating a packaging container for keeping freshness of fruits and vegetables according to the present invention, first, a predetermined amount is placed on the fruits and vegetables (hereinafter, also referred to as “vegetables 1”). Inoculate with A1 bacteria.
There is no particular limitation on the type of fruits and vegetables 1, and the fruits and vegetables may be the same type as the fruits and vegetables intended to be stored in the packaging container to maintain the freshness (hereinafter, also referred to as “vegetables 2”). It may be a type of fruit or vegetables.
From the viewpoint of accurately evaluating the freshness retention performance of the fruits and vegetables 2 in the packaging container, it is preferable that the fruits and vegetables 1 and 2 are the same type of fruits and vegetables, and at least the similar fruits and vegetables are preferable.
From the viewpoint of evaluating the freshness retention performance of the packaging container in a short time, it is preferable that the fruits and vegetables 1 are fruits and vegetables in which the bacteria to be ingested easily grow, and in that case, the fruits and vegetables 1 and 2 are different types of fruits and vegetables. It does not matter if there is.

  Specific examples of fruits and vegetables 1 are lettuce, cabbage, radish, carrot, yam, burdock, tomato, cucumber, eggplant, pepper, edamame, okra, mung bean sprouts, soybean sprouts, pearl millet, shiitake mushrooms, shimeji mushrooms, eringi, maitake mushrooms, broccoli, broccoli. , Spinach, komatsuna, bok choy, asparagus, banana, mango, plum, apple, strawberry, mandarin orange, grape, Japanese pear, and pear, and combinations thereof, but are not limited thereto.

  In particular, it is preferable to use, as the fruits and vegetables 1, fruits and vegetables containing at least one selected from the group consisting of lettuce, cabbage, and radish. Lettuce, cabbage, and radish are often eaten raw, and it is particularly necessary to suppress the growth of various bacteria on them as fruits and vegetables 2. Therefore, even fruits and vegetables 1 are selected from the group consisting of lettuce, cabbage, and radish. This is because the freshness-keeping performance of the fruit and vegetables 2 in the packaging container can be evaluated with higher accuracy by using the fruit and vegetables containing at least one of

The "lettuce" in this embodiment is a concept including general vegetables belonging to the genus Chisha species of the Asteraceae family Asteraceae, and is not limited to vegetables distributed under the name "lettuce" itself.
That is, the "lettuce" referred to here is a type of scraping chisha or cutting lettuce typified by santu, which is a type of scraping leaves from the stem; typified by romaine lettuce, etc. All of the type called chisha; non-heading leaf lettuce (leaf chisha), which is represented by sunny lettuce and green leaf; and heading ball lettuce (ball chicha), which is typically represented by lettuce. Is a concept that includes.
Preferable specific examples of "lettuce" here are lettuce (tama lettuce), green leaf, romaine lettuce (cos lettuce), sunny lettuce, silk lettuce, pink roaster, salad vegetable, bouquet lettuce, green oak leaf (saranova lettuce), frills. Examples include, but are not limited to, lettuce, (chima) santu, stem lettuce (stem lettuce), and the like.

The "cabbage" in this embodiment is a concept including general headed vegetables belonging to the genus Brassica of the Brassicaceae family, and is not limited to vegetables distributed under the name "cabbage" itself.
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.

The “radish” in this embodiment is a concept including general vegetables belonging to the genus Radish of the family Cruciferae, and is not limited to the vegetables distributed under the name “radish” itself.
That is, the "radish" here is generally known varieties, such as blue-necked radish, white-necked radish, spicy radish, etc., but is not particularly limited to varieties and the like, other radish (radish), Varieties such as horseradish, black radish, and Japanese radish may also be used.
Further, the part of "radish" is generally a root, but it is not particularly limited to this, and may be a leaf or a stem, or a combination of these, for example, a leafy radish. It may be something like this. Further, the “radish” is not limited to the one obtained by peeling the skin, and may include the skin partially or entirely.

The form of the fruits and vegetables 1 is not particularly limited, but since cut vegetables, which have high economic value and importance of keeping freshness, are often used as the fruits and vegetables 2 described later, from the viewpoint of highly accurate evaluation, Vegetables and fruits 1 are also preferably cut vegetables. From the viewpoint of making the evaluation conditions as stable as possible, it is preferable to wash the fruits and vegetables 1 with water or the like before inoculation and storage.
The amount of the fruits and vegetables 1 is not particularly limited, and it is preferable to select an amount that is large enough not to limit the growth of bacteria and not too large not to impair the uniformity of evaluation. From the viewpoints of ease of evaluation, suppression of variation between samples, etc., it is preferable that the amount is smaller than that of the fruits and vegetables 2 stored in the package which is a product.

In the step of inoculating a predetermined amount of the bacterium A1 onto the fruits and vegetables 1, there is no particular limitation on the kind of the bacterium to be inoculated, and even if the bacterium is the same as the bacterium of which the growth on the fruits and vegetables 2 is particularly concerned. Well, it may be different types of bacteria.
From the viewpoint of accurately evaluating the growth inhibitory performance of a bacterium of which the growth is particularly concerned by the packaging container, the bacterium to be inoculated is preferably the same type as the bacterium of which the growth is particularly concerned, and at least similar. It is preferably a bacterium.
From the viewpoint of evaluating the freshness retention performance of the packaging container in a short time, it is preferable that the inoculated fungus is a fungus that easily grows on the fruit and vegetables 1, and in that case, a kind different from the fungus whose growth is particularly concerned. It doesn't matter even if they are fruits and vegetables. Even in that case, it is desirable that the properties such as aerobic, anaerobic, facultative anaerobic and the like are common to those of the bacteria in which the growth is particularly concerned.

  Specific examples of the inoculum include Escherichia coli, Bacillus cereus, Listeria monocytogenes, pathogenic Escherichia coli 0-157, Salmonella, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Vibrio, black mold, or blue mold, or these. Combinations can be included, but are not limited to.

In the step of inoculating a predetermined amount A1 of bacteria on the fruits and vegetables 1, the inoculation amount A1 is not particularly limited, and the bacteria can easily grow, and the bacteria which can actually exist on the surface of the fruits and vegetables in the package for keeping freshness. It is preferable to appropriately set the amount depending on the amount, the necessity of acceleration in evaluation, and the like.
As the specific inoculation amount A1, if it is too large, it may be saturated, so the upper limit is, for example, 1.0 × 10 ⁷ or less, and if it is too small, detection becomes difficult, for example, 1.0 × 10 ² or more, preferably 1.0 × 10 ^{4 to} 1.0 × 10 ⁶ cells, more preferably 1.0 × 10 ^{5 to} 1.0 × 10 ⁶ cells, can be inoculated.

Process of storing fruits and vegetables 1 in a packaging container and sealing the packaging container, which is an evaluation target of the present invention , and the packaging container for containing the fruits and vegetables 1 therein is not particularly limited, but the cost, appearance, From the viewpoint of lightness and the like, a packaging container including a polymer film is preferable. 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 preferable packaging container described above may be a flexible packaging container in which all or main parts are made of a flexible polymer film, a so-called packaging bag, and the flexible polymer film and the coating. It may be a flexible packaging container in which other flexible members such as paper are combined, or a packaging container in which a flexible polymer film and a rigid member are combined, for example, as a lid material. It may be in the form of a combination of the polymer film described above and 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 oxygen permeability of the packaging container containing the polymer film which is a preferred evaluation is not particularly limited, but for example, the oxygen permeability thereof is 10,000 cc / m ² / atm / day or less at 20 ° C. and 90% RH. Is preferred. When the oxygen permeability of the packaging container is within the above range, it becomes easier to control the oxygen concentration in the packaging container, and the oxygen concentration 24 hours after the packaging container is sealed is 0% by volume or more and 5% by volume or less. This is because it becomes easier to set
Oxygen permeability of the packaging container is more preferably at most ^{6000cc / m 2 / atm / day} , even more preferably at most ^{3500cc / m 2 / atm / day} .
There is no particular lower limit to the oxygen permeability of the packaging container, but when a polymer film having a realistic cost and thickness is used, it is often 500 cc / m ² / atm / day or more. It is preferable to select an appropriate oxygen permeability in consideration of the shape and size of the packaging container, the type and amount of contents to be stored in the packaging container, and the like.

Polymer Film As described above, the packaging container to be preferably evaluated preferably contains a polymer film, and the oxygen permeability of the polymer film at this time is 20 ° C. and 90% RH, It is particularly preferably 10,000 cc / m ² / atm / day or less. That is, in this embodiment, in order to achieve the desired internal oxygen concentration described above, it is desirable to configure the packaging container using a polymer film having an oxygen permeability of a predetermined value or less.
Oxygen permeability of the polymer film is more preferably at most ^{6000cc / m 2 / atm / day} , even more preferably at most ^{3500cc / m 2 / atm / day} .
When the oxygen permeability at 20 ° C. and 90% RH is less than or equal to a predetermined value, it is more preferable to prevent oxygen from entering from the outside air and to set the oxygen concentration after a predetermined time after sealing the packaging container to a desired value. It will be easier.
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 preventing odors from being stored in the 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 1000 cc / m ² / atm / day or more, and preferably 3500 cc / m ² / atm / day or more. Particularly preferred.

The oxygen permeability of the polymer film used in this embodiment 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 (a × b × 2 cm 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, the oxygen permeability at 20 ° C. and 90% RH can be 500 cc / m ² / atm / day or more by setting the thickness to 45 μm or less. .. Considering mechanical strength and the like, 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, from the viewpoint of achieving an oxygen permeability of 10,000 cc / m ² / atm / day or less in the preferred embodiment of the present invention, it is preferable that the polymer film has no opening.
Since it is not necessary to provide openings in the polymer film, the manufacturing process becomes simpler and less expensive, and it is not necessary to precisely control the size and shape of the openings.
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 maintaining the freshness of fruits and vegetables having a large respiration rate, when it is necessary to use a thick polymer film and / or a polymer material having low oxygen permeability, In order to achieve the desired 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 forming micropores, 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 embodiment, when a laser is used for the fine pore opening, it is preferable that the target film efficiently absorb the 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, the laser hole processing preferably used in the production of the package of the embodiment is different from the slit processing, since there is no physical contact with metal, there is no risk of a missing blade, needle, etc. mixing, and the opening area is in the slit. Compared with the above, the quality control (control of gas permeability) is easy because it is constant, which is preferable.
As slit processing, 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. The number of openings in the area is a guide. 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. When one is provided, it has an effect of increasing the oxygen permeability of about 1000 cc / m ² / day / atm for each one present in a packaging container of 200 mm × 200 mm, and the packaging required based on such knowledge. It is preferable to determine the number of slit openings from the oxygen permeability of the entire 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 the present embodiment, suitable oxygen permeability, flexibility when forming a packaging container, strength, transparency, economic efficiency, etc., when providing an opening. From the viewpoint of accuracy and easiness in forming the opening, etc., 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 15 to 45 μm, more preferably 20 to 40 μm.

Further, 20 ° C. of the polymer film used in this embodiment, it is preferable that carbon dioxide permeability at 90% RH or less ^{10000cc / m 2 / atm / day} , or less 6000cc ^/ m 2 ^/ atm ^/ day Is particularly preferable.
When the carbon dioxide permeability at 20 ° C. and 90% RH is less than or equal to a predetermined value, the invasion of carbon dioxide from the outside air is prevented, and the carbon dioxide concentration after a predetermined time after sealing the packaging container is within a preferable range. Becomes even easier.
There is no particular lower limit to the carbon dioxide permeability of the polymer film, but as long as an ordinary polymer film that is not subjected to gas barrier coating or the like is used, at 20 ° C. and 90% RH, 500 cc / m ² / atm / Generally, it is not less than day.

  The carbon dioxide permeability of the polymer film used in this embodiment can be measured by the same method as the oxygen permeability.

  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, one of these materials may be used alone, or a plurality of these materials may be blended and / or laminated and used.

  From the viewpoint of ease 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 process low-density polyethylene, linear low-density polyethylene (LLDPE), ethylene-based polymers such as high-density polyethylene, propylene homopolymer, propylene / α-olefin random copolymer, propylene block copolymer Examples include propylene-based polymers such as, and polyolefins 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 and 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.

The polymer film preferably used for the packaging container in the present embodiment 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 thus can be particularly preferably used in the packaging container of the present embodiment.
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 suitable polymer films constituting the packaging container in the present embodiment 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 this embodiment 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-based film preferably used in this embodiment is a film containing the ethylene-based 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 which is preferably used in the present embodiment 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, the surface of the polymer film, in particular, the surface on the inner side of the packaging container, a specific amount of a specific surfactant is present, or the polymer film contains a specific amount of a specific surfactant, It may 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. Thereby, the packaging container can be easily and efficiently sealed.

In this step, after the fruits and vegetables 1 are stored in the packaging container, the packaging container is sealed. The method of sealing the packaging container is not particularly limited, and heat sealing, adhesion, mechanical sealing with other members, or the like can be appropriately selected. By sealing, it is possible to prevent the inflow of the outside air and the outflow of the internal gas, and to perform the evaluation with higher accuracy.
It is preferable to perform the heat sealing because the sealing can be surely performed at a relatively low cost.

Step of storing the sealed packaging container at a prescribed storage temperature for a prescribed time In the evaluation method of the present embodiment, after the fruits and vegetables 1 are stored in the packaging container and the packaging container is sealed, the packaging container is sealed in a predetermined manner. Hold at storage temperature for a specified time.
The storage temperature in this step is not particularly limited, and can be appropriately set in consideration of the normal storage temperature of fruits and vegetables, particularly the fruits and vegetables 2 described later, and the relationship between the growth of bacteria and the temperature.
From the viewpoint of accurately evaluating the freshness retention performance of the packaging container in the actual package, etc., the temperature is preferably close to the storage temperature in the distribution of the actual product, package, etc.
On the other hand, from the viewpoint of evaluating the performance of the packaging container in a short time, it is preferable that the temperature is a temperature at which bacterial growth easily proceeds.
Specifically, for example, it can be stored at about 25 ° C.

The storage time in this step is also not particularly limited, and depends on the storage time in the distribution of the actual product, such as a package, whether the storage temperature is intended to accelerate the growth of bacteria, and the like. Can be set appropriately.
Specifically, for example, it is preferable to store it for about 24 hours.

A process of taking out fruits and vegetables 1 from the packaging container, measuring the number A2 of the bacteria on the fruits and vegetables 1, and determining that the ratio A2 / A1 is a predetermined value or less as a non-defective product, in the evaluation method of the present invention, a predetermined storage temperature After storing for a predetermined time in 1., the fruits and vegetables 1 are taken out from the packaging container, and the number of the bacteria on the fruits and vegetables 1 is measured. According to the number of bacteria obtained by the measurement, if the number of bacteria is equal to or less than a predetermined value, the packaging container is determined to be a good product having sufficient fungal growth inhibitory performance, and if the number exceeds the predetermined value, the packaging container is unfit. Judge as good product.
The method for measuring the number of bacteria is not particularly limited, and can be appropriately selected depending on the type, amount, expected degree of growth, etc. of the bacteria, for example, standard agar medium, plate pour method You can
Specifically, the surface of one sample of fruits and vegetables is inoculated with a bacterium suspension in a prescribed amount, and then sealed in a closed container having a predetermined internal gas composition and allowed to stand at 25 ° C. for 24 hours. The viable cell count of the sample after standing was measured by pulverizing the sample with a mixer, serially diluting it with physiological saline, and performing pour culture (35 ° C, 48 hours) using a standard agar medium. Number A2 is measured.
The viable cell count A1 of the inoculated bacterial suspension is similarly measured by pour culture (35 ° C., 48 hours) using a standard agar medium on the same day as the bacterial suspension inoculation of one sample of fruits and vegetables.

As a result of the measurement, if the ratio A2 / A1 between the number A2 of bacteria on the fruit and vegetables 1 and the number A1 of inoculum is less than or equal to a predetermined value, the packaging container can be determined to be non-defective.
The packaging container thus judged to be non-defective can be used as it is for the production of a package for keeping the freshness of fruits and vegetables.
However, since many packages for keeping freshness of fruits and vegetables which are products are usually produced, it is troublesome and costly to evaluate all the packaging containers used therein by the evaluation method of the present invention. There is a risk.
Therefore, using the packaging container obtained in the same lot as the packaging container determined to be non-defective according to the evaluation method of the present invention to produce a package for keeping freshness of fruits and vegetables, and determined to be non-defective according to the evaluation method of the present invention. It is preferable to manufacture a package for keeping the freshness of fruits and vegetables using a packaging container manufactured using the same raw film as the packaging container described above, and these are also preferred embodiments of the present invention.

The predetermined value of the ratio A2 / A1 which is the criterion of the above-mentioned determination is the type of bacteria, the inoculum of the bacteria, the type, amount and form of fruits and vegetables 1, the type, amount and form of fruits and vegetables 2, the storage condition of the package, It can be set as appropriate in consideration of the above.
Considering that the test of the present invention is a certain kind of accelerated test in which a fungus is intentionally inoculated, the predetermined value of the above ratio A2 / A1 is acceptable in a package for keeping freshness of A2 of fruits and vegetables. The number may be higher than the number of bacteria.

Further, as a criterion for judging the quality of the packaging container, after inoculating the fruits and vegetables 1 with the same predetermined amount of A1 bacteria, the number B2 of the bacteria after storage in air
It is also possible to use the ratio of (B2 / A1) and (A2 / A1), that is, (B2 / A2) by determining (B2 / A1) by measuring. More specifically, when the ratio (B2 / A2) is 6 or less, it can be determined as a non-defective product.
(B2 / A1) is preferably 20 or less, more preferably 100 or less.
Here, the number B2 of the bacteria after storage in air is
A step of inoculating a predetermined amount of A1 bacteria on the fruits and vegetables 1,
Storing the fruits and vegetables 1 in a packaging container under an air atmosphere and sealing the packaging container,
It can be measured by a step of storing the packaging container at a predetermined storage temperature for a predetermined time, and a step of taking out the fruits and vegetables 1 from the packaging container and measuring the number B2 of the bacteria on the fruits and vegetables 1.

Method for producing a package for keeping freshness of fruits and vegetables As described above, it is the present invention to produce a package for keeping freshness of fruits and vegetables by using a packaging container judged to be non-defective by the evaluation method of the present invention. Is a preferred embodiment of.
That is, the method for producing a package for maintaining freshness of fruits and vegetables, which is a preferred embodiment of the present invention,
A step of preparing a packaging container containing a polymer film,
In the evaluation method of the present invention, a step of evaluating the packaging container,
A step of storing and sealing fruits and vegetables (hereinafter, also referred to as "fruits and fruits 2") which may be the same as or different from the fruits and vegetables 1 in a packaging container determined to be non-defective in the evaluation step,
And a method for producing a package for keeping freshness of fruits and vegetables.

Similarly, as described above, using the packaging container obtained in the same lot as the packaging container determined to be non-defective in the evaluation method of the present invention to produce a package for keeping freshness of fruits and vegetables, and the evaluation method of the present invention It is also a preferred embodiment of the present invention to manufacture a package for keeping the freshness of fruits and vegetables using a packaging container manufactured using the same raw film as the packaging container determined to be non-defective.
That is, the method for producing a package for maintaining freshness of fruits and vegetables which is another preferred embodiment of the present invention,
A step of preparing a packaging container containing a polymer film,
In the evaluation method of the present invention, a step of evaluating the packaging container,
A step of storing and sealing the fruits and vegetables 2 in a packaging container obtained in the same lot as the packaging container determined to be non-defective in the evaluation step,
And a method for producing a package for keeping freshness of fruits and vegetables.

Also, a step of preparing a packaging container containing a polymer film,
In the evaluation method of the present invention, a step of evaluating the packaging container,
A step of accommodating and sealing the fruits and vegetables 2 in a packaging container manufactured using the same raw film as the packaging container determined to be non-defective in the step of evaluating,
A method for producing a package for keeping freshness of fruits and vegetables having the above is also a method for producing a package for keeping freshness of fruits and vegetables which is another preferred embodiment of the present invention.

In the method for producing a package for keeping freshness of fruits and vegetables of these embodiments, a step of preparing a packaging container containing a polymer film, and a step of evaluating the packaging container by the evaluation method of the present invention are both This is the same as that described above in relation to the method for evaluating the packaging container for keeping freshness of fruits and vegetables according to the present invention.
By using a packaging container evaluated to be non-defective, a packaging container obtained in the same lot as the packaging container determined to be non-defective, and a packaging container manufactured using the same raw film as the packaging container determined to be non-defective, It is possible to produce a package having particularly excellent freshness retention performance.

Step of storing and sealing fruits and vegetables 2 in a packaging container The fruits and vegetables 2 used in the present embodiment are those in which the freshness is maintained in the packaging body which is a product.
There is no particular limitation on the type of the fruits and vegetables 2, and may be the same as or different from the fruits and vegetables 1 described above. Preferred types of fruits and vegetables are similar to those described above for fruits and vegetables 1, with lettuce, cabbage, or radish or a combination thereof being particularly preferred. More preferably, both fruits and vegetables 1 are lettuce or both are cabbage.

There is no particular limitation on the form of the fruits and vegetables 2. Therefore, the fruits and vegetables 2 may be as-harvested, may be so-called pretreated after removing outer leaves or the like, or may be cut fruits and vegetables, so-called cut vegetables. The fruits and vegetables 2 may be those that have been subjected to any or all of the treatments such as washing, cooling, and dehydration, or may be those that are not subjected to any of these treatments.
When the fruits and vegetables 2 stored and kept fresh are cut vegetables, it is preferable that cutting, washing, dehydration and / or drying treatment is performed to adjust the water content to an appropriate amount. For example, when the cut vegetables are cut lettuce, the lettuce is washed at 80 to 120 ppm for 10 to 20 minutes with hypochlorous acid according to the “Massive Cooking Facility Hygiene Management Manual” (Ministry of Health and Welfare), and then “let's say Based on the "Analysis method" (Consumer Affairs Agency), it is necessary to keep the water content in the range of 20 to 30%, which is measured based on the weight loss when vacuum drying at 70 ° C for 5 hours, to prevent odor generation and browning. It is particularly preferable from the viewpoint of the balance of prevention of deterioration of external appearance.

  Demand for cut vegetables has been increasing in recent years because they can be easily used for meals, and has high economic value. On the other hand, when vegetables are cut, their respiratory action and metabolic reaction are rapidly activated and their quality tends to be sharply reduced. Since the present embodiment can be effectively used to maintain the freshness of such cut vegetables, it has a particularly high economic value.

By storing and sealing the fruits and vegetables 2 in a packaging container, a package according to a preferred embodiment of the present invention can be manufactured, and a freshness maintaining method for fruits and vegetables according to another preferred embodiment of the present invention is provided. Can be implemented.
At that time, it is preferable to appropriately adjust the internal oxygen concentration of the packaging container, and it is also preferable to enclose carbon dioxide or nitrogen.
In the following, the process of storing and sealing the fruits and vegetables 2 in a packaging container is used as the fruits and vegetables 2, which is cut, washed, dehydrated, and / or dried, and cut lettuce adjusted to an appropriate water content is used as an example. Explained.

  First, in a pretreatment step, the outer leaf is manually removed, divided into 2 to 4, and the lettuce from which the core has been removed is supplied to the conveyor. The lettuce conveyed by the conveyor is cut with a slicer, and also serves as a cooling bath in a washing tank filled with cold water. Based on the “Massive Cooking Facility Hygiene Management Manual” (Ministry of Health and Welfare), 80-120 ppm, 10-20 minutes of hypochlorous acid It is washed with water, drained and then dehydrated with a centrifugal dehydrator or the like. The dehydrated cut lettuce is packed in a packaging container (one side of which is not sealed) containing a polymer film determined to be non-defective, and after weighing, the packaging container is sealed to maintain the freshness of the cut lettuce. The packaging body is manufactured.

From the viewpoint of maintaining the freshness of cut lettuce, it is preferable to use a blade with good sharpness and to 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, the wider the cut width is, as long as it meets the demand form.
Further, if a large amount of various bacteria adheres to the cut lettuce from the beginning, it becomes more difficult to maintain the freshness. Therefore, it is preferable to thoroughly clean the cut lettuce to reduce the adhesion of the other 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 lettuce after washing. Even if the water is drained after standing still after washing, since much water still adheres to the surface of the cut lettuce, 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 It is preferable that the amount of water measured based on the weight loss when dried under reduced pressure at 70 ° C. for 5 hours based on the Agency) is in the range of 20 to 30%.

In the method for producing a freshness-keeping package for fruits and vegetables according to this embodiment, carbon dioxide may be sealed and / or deaerated after the fruits and vegetables 2 are stored and the packaging container is sealed. By encapsulating and / or deaerating carbon dioxide, it is possible to quickly reach the desired oxygen concentration and preferred carbon dioxide concentration designed as an equilibrium state between the oxygen permeability of the packaging container and the respiration rate of fruits and vegetables 2. And 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.

By the production method of the present embodiment, it is possible to effectively suppress the growth of various bacteria such as Escherichia coli on the fruits and vegetables 2, and to produce a package for keeping the freshness of fruits and vegetables, which is particularly excellent in the freshness keeping performance. be able to.
The internal carbon dioxide concentration of the package for keeping freshness of fruits and vegetables produced by the production method is preferably 8% or more and 60% or less in volume%.
When this condition is satisfied, the growth of various bacteria on the fruits and vegetables 2 can be suppressed more effectively, and the growth of molds such as black mold can be suppressed more effectively.
The carbon dioxide concentration in the packaging container can be measured by, for example, a food packaging O ₂ / CO ₂ analyzer Check Mate 3 manufactured by Dansensor.

The oxygen concentration in the package in the present embodiment is not particularly limited, and is appropriately set depending on the type of bacteria in which growth is particularly concerned, particularly anaerobic bacteria, facultative anaerobic bacteria, aerobic bacteria, etc. be able to.
Since aerobic bacteria and facultative anaerobic bacteria generally grow more easily than anaerobic bacteria, it is preferable that the oxygen concentration in the package is low from the viewpoint of suppressing the growth of all bacteria.
On the other hand, when the growth of the anaerobic bacteria is particularly concerned, for example, when the growth of the anaerobic bacteria is particularly concerned depending on the type and the mode of the fruits and vegetables 2, the oxygen concentration in the package may be set high.
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.

In the package of the present embodiment, only the fruits and vegetables 2 such as lettuce may be stored in the packaging container, or other members may be stored.
For example, in addition to the fruits and vegetables 2, 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 the influence on the fruits and vegetables 2 and the use near the fruits and vegetables 2 as food. 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, or the like. no problem.

  There is no particular limitation on the antibacterial agent, and substances having an antibacterial action can be appropriately used, but there is relatively little concern about the effects on the fruits and vegetables 2 and the use near the food or fruits 2 and the like. Agents 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.
(Bacterial load)
The measurement was carried out by the method described below. E. coli Escherichia coli NBRC 3972 was cultivated in Trypticase Soy Broth medium (concentration 1/1, normal concentration) at 35 ° C. for 24 hours, and then fresh Trypticase Soy Broth medium (concentration 1/100 ) Was used to prepare a bacterial suspension (D0 inoculum bacterial solution).
As the lettuce sample, commercially available sterile lettuce was used. As a blank test, the number of bacteria was measured after holding at 25 degrees for 24 hours in the same manner as in Examples described below, except that the sterile lettuce was not inoculated, but all the bacteria were below the detection limit. ..
The lettuce sample was inoculated on the surface of the lettuce sample with the liquid amount described in the product name, and the lettuce sample was allowed to stand at 25 ° C. for 24 hours in a closed container having a predetermined internal gas composition. Regarding the viable cell count of each sample after standing, each sample was serially diluted with sterilized peptone-containing physiological saline, and the bacterial count A2 was measured by pour culture (35 ° C, 48 hours) using standard agar medium. did.
The viable cell count A1 of the inoculated bacterial suspension (D0 inoculated bacterial solution) was determined by pour culture (35 ° C, 48 hours) using standard agar medium on the same day as the bacterial suspension inoculation on the lettuce sample. It measured similarly.
(container)
Using a Mitsubishi Gas Chemical Co., Ltd. culture container "Aneropack", the vegetables inoculated with the bacterial solution were stored in the same container and kept at a predetermined time and temperature. The inside of the container was a square jar having an internal size of about 14 W × 20 L × 10 H (unit: cm), and a pipe for sucking and discharging gas was attached to the side surface to adjust the gas atmosphere inside.
In this embodiment, a jar-shaped container is used to store a plurality of samples, but a film-shaped individual packaging material can be used in carrying out the present invention.

(Example 1)
After inoculating 0.3 cc of Escherichia coli inoculum solution (bacteria number: 2.80 × 10 ⁴ ) on cut lettuce weighing about 2.2 g, it was placed in the above-mentioned Aneropack container, and then in the packaging container. Carbon dioxide was introduced to adjust the internal carbon dioxide concentration to 100%, and then the packaging container was hermetically sealed to produce a package in which cut lettuce was stored in the packaging container. Under this condition, the total number of samples in the package was 2.
Each of the packages was held at a temperature of 25 ° C.
At 24 hours after sealing, the cut lettuce was taken out and the number of Escherichia coli on the cut lettuce was measured. The predetermined value (reference value) of the number of bacteria for judging the quality of the packaging container was set to 1/6 or less of the number of bacteria measured in the air atmosphere under the same conditions.
The results are shown in Table 1.
The number of Escherichia coli on cut lettuce after 24 hours from the sealing was about 0.003 times the number of bacteria measured in an air atmosphere under the same conditions, and the packaging container was evaluated as a good product.

(Comparative Example 1)
After the cut lettuce was stored, the packaging container was evaluated in the same manner as in Example 1 except that nitrogen was enclosed in place of carbon dioxide in the packaging container, and the total number of samples in the packaging body was 2.
The results are shown in Table 1.
The number of Escherichia coli on cut lettuce after 24 hours from the sealing was about 0.77 times the number of bacteria measured in an air atmosphere under the same conditions and increased to 1200 times that at the time of inoculation. Since the value was more than 72 times, the packaging container was evaluated as a defective product.

(Example 2)
Example except that 0.1 cc of pathogenic E. coli O-157 inoculum solution (bacteria number: 2.20 × 10 ⁴ ) was inoculated on the cut lettuce instead of 0.3 cc of Escherichia coli inoculum solution. In the same manner as in 1, the total of 2 packages were prepared and evaluated. The predetermined value (reference value) of the number of bacteria for judging the quality of the packaging container was set to 1/6 or less of the number of bacteria measured in the air atmosphere under the same conditions 24 hours after the sealing.
The results are shown in Table 1.
The number of pathogenic Escherichia coli O-157 on cut lettuce after 24 hours from the sealing was about 0.08 times the number of bacteria measured in an air atmosphere under the same conditions, and the packaging container was determined to be a good product. Was evaluated.

(Comparative example 2)
Two packages in total were prepared and evaluated in the same manner as in Example 2 except that nitrogen was enclosed in the packaging container after storing the cut lettuce instead of carbon dioxide.
The results are shown in Table 1.
The number of pathogenic Escherichia coli O-157 on cut lettuce after 24 hours from the sealing was about 0.5 times the number of bacteria measured in the air atmosphere under the same conditions, and the packaging container was a defective product. Was evaluated.

(Example 3)
In place of the 0.1 cc Escherichia coli inoculum solution, inoculated with 0.1 cc of cereus inoculum solution (bacteria number: 6.20 × 10 ² ) on cut lettuce, the same as in Example 1. Then, two packages in total were prepared and evaluated. The predetermined value (reference value) of the number of bacteria for judging the quality of the packaging container was set to 1/6 or less of the number of bacteria measured in the air atmosphere under the same conditions.
The results are shown in Table 1.
The number of Bacillus cereus on the cut lettuce 24 hours after the sealing was approximately 0.012 times the number of bacteria measured in an air atmosphere under the same conditions, and the packaging container was evaluated as a good product.

(Comparative example 3)
A total of two packages were prepared and evaluated in the same manner as in Example 3 except that nitrogen was enclosed in the packaging container after storing the cut lettuce instead of carbon dioxide.
The results are shown in Table 1.
The number of Bacillus cereus on the cut lettuce 24 hours after the sealing was approximately 0.38 times the number of bacteria measured in an air atmosphere under the same conditions, and the packaging container was evaluated as a defective product. ..

(Example 4)
The same procedure as in Example 1 was performed except that 0.1 cc of the Listeria monocytogenes inoculum solution (the number of bacteria: 6.00 × 10 ⁴ ) was inoculated on the cut lettuce instead of the 0.1 cc Escherichia coli inoculum solution. Then, two packages in total were prepared and evaluated. The predetermined value (reference value) of the number of bacteria for judging the quality of the packaging container was set to 1/6 or less of the number of bacteria measured in the air atmosphere under the same conditions.
The results are shown in Table 1.
The number of Listeria monocytogenes on cut lettuce 24 hours after the sealing was approximately 0.09 times the number of microbes measured in an air atmosphere under the same conditions, and the packaging container was evaluated as a good product.

(Comparative example 4)
Two packages were prepared and evaluated in the same manner as in Example 4 except that nitrogen was enclosed in the packaging container after storing the cut lettuce instead of carbon dioxide.
The results are shown in Table 1.
The number of Listeria monocytogenes on cut lettuce 24 hours after the sealing was about 0.9 times the number of bacteria measured in an air atmosphere under the same conditions, and the packaging container was evaluated as a defective product. ..

(Example 5)
The test was performed according to Examples 1 to 4 except that the packaging container was prepared by changing the packaging container to a bag-shaped container made of an OPP (stretched polypropylene) film.
After storing the package at a temperature of 25 ° C. for 24 hours, the cut lettuce was taken out from the package, and the number of general bacteria, the number of Escherichia coli, the number of Staphylococcus aureus, the number of Vibrio parahaemolyticus, the number of Salmonella on the surface of the cut lettuce, And the number of Bacillus cereus were evaluated.
General bacterial count is 5.2 × 10 ⁶ (CFU / g), Escherichia coli count is less than 3 (MPN / g), Staphylococcus aureus count is less than 100 (CFU / g), Vibrio parahaemolyticus count is 1 (MPN / g) ), The number of Salmonella bacteria was less than 1 (MPN / g), and the number of Bacillus cereus was less than 100 (CFU / g), and the growth of various bacteria was effectively suppressed.
(Example 6)
A package was prepared and evaluated in the same manner as in Example 5, except that cut cabbage was stored in a packaging container instead of the cut lettuce.
The number of general bacteria on the surface of cut lettuce was 5.1 × 10 ⁷ (CFU / g), the number of Escherichia coli was less than 3 (MPN / g), and the number of Staphylococcus aureus was 24 hours after storage at a temperature of 25 ° C. Less than 100 (CFU / g), Vibrio parahaemolyticus number is less than 1 (MPN / g), Salmonella number is less than 1 (MPN / g), and number of cereus bacteria is less than 100 (CFU / g). It was effectively suppressed.

  The method for evaluating a packaging container for keeping freshness of fruits and vegetables of the present invention, and the packaging body and the method for producing the same using the method can stably and effectively suppress the propagation of various bacteria on fruits and vegetables. , It is possible to maintain the hygiene and safety of the cut vegetables stored in the packaging container, and to effectively prevent the deterioration of the appearance and the generation of offensive odors. Has high availability in.

Claims (9)

A method of evaluating a packaging container for keeping freshness of fruits and vegetables,
A step of inoculating a predetermined amount of A1 bacteria on the fruits and vegetables 1,
Storing the fruits and vegetables 1 in a packaging container containing carbon dioxide and sealing the packaging container;
A step of storing the packaging container at a prescribed storage temperature for a prescribed time, and taking out the fruits and vegetables 1 from the packaging container, measuring the number A2 of the bacteria on the fruits and vegetables 1, and determining that the ratio A2 / A1 is not more than a prescribed value. Process to judge as good product,
And an evaluation method.   The fruits and vegetables 1 are lettuce, cabbage, radish, carrot, potato, burdock, tomato, cucumber, eggplant, pepper, edamame, okra, mung bean sprouts, soy bean sprouts, pearl millet, shiitake mushrooms, shimeji mushrooms, eringi, maitake mushrooms, matsutake mushrooms, broccoli, spinach. The evaluation method according to claim 1, wherein the evaluation method is at least one selected from the group consisting of, komatsuna, bok choy, asparagus, banana, mango, plum, apple, strawberry, mandarin orange, grape, Japanese pear, and pear.   At least one selected from the group consisting of Escherichia coli, Bacillus cereus, Listeria monocytogenes, pathogenic Escherichia coli 0-157, Salmonella, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Vibrio, black mold, and blue mold. The evaluation method according to claim 1 or 2, which is a seed. A step of preparing a packaging container containing a polymer film,
A step of evaluating the packaging container by the evaluation method according to any one of claims 1 to 3,
A step of storing and sealing the fruits and vegetables 2 in a packaging container determined to be non-defective in the evaluation step,
And a method for producing a package for keeping freshness of fruits and vegetables. A step of preparing a packaging container containing a polymer film,
A step of evaluating the packaging container by the evaluation method according to any one of claims 1 to 3,
A step of storing and sealing the fruits and vegetables 2 in a packaging container obtained in the same lot as the packaging container determined to be non-defective in the evaluation step,
And a method for producing a package for keeping freshness of fruits and vegetables. Vegetables 1 and 2 are both lettuce or both are cabbage,
The inoculum A1 of the bacterium is 1.0 × 10 ⁷ or less,
The holding temperature of the packaging container is 25 ° C., the holding time is 24 hours,
A method for producing the package for keeping the freshness of fruits and vegetables according to claim 4 or 5. A step of inoculating a predetermined amount of A1 bacteria on the fruits and vegetables 1,
Storing the fruits and vegetables 1 in a packaging container under an air atmosphere and sealing the packaging container,
The fungus after storage in air measured by a step of storing the packaging container at a predetermined storage temperature for a predetermined time, and a step of taking out the fruits and vegetables 1 from the packaging container and measuring the number B2 of the bacteria on the fruits and vegetables 1. The method for producing a package for keeping freshness of fruits and vegetables according to claim 6, wherein when the ratio (B2 / A2) of the number A2 of the bacterium and the number A2 of the bacterium is 6 or less, it is determined as a non-defective product.   A package comprising the fruit and vegetables 1 housed and sealed in a packaging container determined to be a non-defective product by the method according to any one of claims 1 to 3. The package according to claim 8, wherein the internal carbon dioxide concentration is 8% or more and 60% or less in volume%.