JPH0565178A - Food storage method and container used therefor - Google Patents

Abstract

(57) [Summary] [Structure] A method for preserving food, characterized in that the food is filled and sealed in a container formed by adding chitosan and silver to at least part or all of the inner surface in contact with the contents, and the method is used. container. .. [Effect] The storage period can be extended only by packaging the food containing lactic acid bacteria and other microorganisms, which is a problem in storage.
Further, the storage method according to the present invention can be performed only by packaging,
Since the purpose can be achieved, there is no need to change the conventional manufacturing process, which is very economical.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for storing packable food products and a container used for the same.

[0002]

2. Description of the Related Art As a method for preventing spoilage of foods by microorganisms, there are sterilization by heating, inhibition of growth of microorganisms by removing oxygen by an oxygen absorber or gas displacement packaging, addition of a preservative and the like. When sterilization is performed by heating, some foods cannot be sterilized by heating because the quality of the food is deteriorated and the quality such as browning occurs. When oxygen is removed, the growth of aerobic bacteria that require oxygen can be inhibited, but the growth of anaerobic bacteria cannot be inhibited.

Chitosan is a shell of crustaceans, insects, shells,
It is obtained by deacetylating chitin existing in fungi with concentrated alkali and has the effect of inhibiting the growth of lactic acid bacteria, and is added to food or at least partially or entirely on the inner surface in contact with the contents of the container. Has been used.

Depending on the species, lactic acid bacteria include those that can grow at a low temperature range of 5 ° C. and those that can grow even at a relatively high temperature of around 45 ° C., in about 10% salt or at pH 4.0.
Some can grow in a low acidity region. It is a facultative anaerobic bacterium that can grow with or without oxygen and is resistant to many antibacterial substances. Therefore, lactic acid bacteria have become a problem in food preservation. Lactic acid bacteria are considered to be causative bacteria such as rancidity of dairy products such as butter, ham, sausage, net of fish paste products, offensive odor, mayonnaise rot, rot of dough consisting of flour, and roasted raw meat such as minced meat. Has been.

Chitosan is an excellent substance that inhibits the growth of such lactic acid bacteria, but it is ineffective against microorganisms other than lactic acid bacteria, or is extremely weak.

[0006] Silver-substituted zeolite is a zeolite (Zeolit
e, Zeolite) sodium ion is replaced with silver ion, and silver-substituted zeolite is kneaded into the inner resin layer of the packaging container that comes into contact with foods, and silver-substituted zeolite particles are formed on the inner resin layer surface of the packaging container. It is already used as a preservative packaging container that has an antibacterial effect on foods by fixing it so as to project. In addition to silver zeolite, montmorillonite and zinc phosphate holding silver ions are also used.

Furthermore, a packaging container having a silver layer formed on the inner surface of a packaging container in contact with foods by a PVD method such as a vacuum deposition method, a sputtering method or an ion plating method is a storage package having an antibacterial effect for foods. It has been put to practical use as a container. In this case, silver is generally vapor-deposited on the surface of the resin layer on the inner surface of the packaging container that comes into contact with foods.

The antibacterial effect of silver has been known for a long time, and it is considered that silver is ionized and eluted into the water of foods, and the eluted silver ions are taken into the body of microorganisms to act. .. That is, silver foil is put in foods, foods are stored in a silver container, silver has been used for a long time in tableware, dentures, etc., and it is extremely safe with antibacterial effect. .. In addition to silver, copper and iron have been found to have antibacterial effects, but due to problems such as safety, they have not been put to practical use for foods. The antibacterial property of this silver has a very broad antibacterial spectrum, but it has been revealed that the antibacterial property against lactic acid bacteria is weak.

[0009]

As described above, chitosan is obtained by deacetylating chitin existing in the shells of crustaceans, insects, shells, and fungi with concentrated alkali, and is highly safe. It is possible to suppress the growth of lactic acid bacteria by the addition amount of the above, and a container provided with chitosan on the surface in contact with food is used for foods in which the growth of lactic acid bacteria is a problem during storage. Further, as described above, the container utilizing the antibacterial property of silver is widely used because it is highly safe and has an antibacterial effect against many microorganisms except lactic acid bacteria.

However, foods in which lactic acid bacteria and other microorganisms pose a problem in storage, for example, foods such as pickles, are prevented from producing acid by lactic acid bacteria when reconstituted with a container in which chitosan is provided on the surface in contact with the food. However, the generation of carbon dioxide by yeast could not be prevented, the container was bulged, and the preservation effect could not be obtained. On the other hand, in the case of packaging in a container to which silver is added, on the contrary, the generation of gas can be prevented, but the generation of acid cannot be prevented, causing a phenomenon that the sourness becomes strong during storage. Therefore, it is possible to easily suppress the growth of lactic acid bacteria and other microorganisms simultaneously,
There has been a demand for a storage method that can extend the storage period.

[0011]

In order to solve the above-mentioned problems, the present invention provides at least a part or all of the inner surface contacting the contents with chitosan and at least a part or all of the inner surface contacting the contents. The present invention provides a method for preserving foods, in which foods are filled and sealed in a container or a packaging bag in which silver is added to the container, and a container used therefor.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The problem was solved by applying chitosan and silver to the surface of a container that comes into contact with food, and filling and sealing the food in this container.

As a method of applying chitosan and silver to the surface of the container used in the present invention that comes into contact with food, chitosan which is a powder and a carrier to which silver ions have been added are kneaded into a resin at the same time to bring the container and the food into contact with each other. A resin layer may be formed, or a container member formed by applying chitosan on the surface in contact with food by a known method, and a container formed by applying silver on the surface in contact with food by a known method. A container used in the present invention may be combined with a member.

The method of applying chitosan to the food-contacting surface of the container used in the present invention is a method of forming a surface of the container in contact with food by kneading chitosan at the same time as melting, and a thermoplastic resin Extruded from the T die on the material,
A method of coating a thermoplastic resin and spraying chitosan powder on the surface of the thermoplastic resin when it is cooled with a cooling roll to form a film, and when the thermoplastic resin is extruded from a T-die to form a sheet, the cooling roll is used. There is a method of applying and applying chitosan powder when cooled and solidified, a method of dispersing chitosan in a binder resin dissolved in a solvent, removing the solvent after application, and applying chitosan. In addition to these, dispersed in UV curable resin, electron beam curable resin, etc.,
A method of applying by curing these resins after application is also possible. It is also possible to form the container by a blow molding method using a parison having a layer in which chitosan is kneaded inside by coextrusion.

A silver zeolite-like material carrying silver ions can also be applied by the same method. In addition to this, a method of applying silver to the surface of resin, metal such as aluminum steel, glass, paper or the like by PVD method such as vacuum deposition method, sputtering method, ion plating method may be used.

As the thermoplastic resin usable in the present invention, polyethylene, polypropylene, vinyl chloride, vinylidene chloride, nylon, polyester and the like can be arbitrarily selected in consideration of processability, food suitability and the like. The kneading amount of the carrier carrying chitosan and silver ions when kneading into the thermoplastic resin is 1 to 50 in total considering antibacterial properties and suitability for packaging materials.
Weight% is suitable, preferably 5 to 25% by weight.

The amount of the carrier loaded with chitosan and silver ions applied to the surface of the heat-melted resin is such that the total amount is 0.1 to 5 g / m ² in a container. Is suitable, and preferably the total amount is 1 to 2.5 g.
It is better to give it so that it becomes / m ² .

Examples of the binder resin usable in the present invention include polyester resins, polyurethane resins, acrylic resins, nitrocellulose resins, acetylcellulose resins, acetate butyrate resins, vinyl resins, epoxy resins and the like. Therefore, it can be arbitrarily selected in consideration of compatibility with the base material.

The amount of carrier carrying chitosan and silver ions dispersed in a binder resin dissolved in a solvent is
It is appropriate that the total amount is 0.1 to 5 g / m ² when the solvent is removed, and the total amount is preferably 1
To 2.5 g / m ² is preferable.

The chitosan used in the present invention has an average molecular weight of 10,000 to 100,000 in view of antibacterial properties.
It is preferably 0, and the degree of acetylation is preferably 95% or more.

The silver zeolite usable in the present invention preferably has a silver substitution rate of 5 to 70%. Further, when a silver layer is provided on the interface of a container that comes into contact with a food product by the PVD method, the part that is involved in the antibacterial property is only the surface of the silver layer. Therefore, it is preferable that the silver layer is as thin as possible from the economical aspect.

The applied amount and the ratio of chitosan and silver can be set depending on the flora of microorganisms in the food to which the present invention is applied, the nutrients that can be utilized by the microorganisms, storage conditions, and the like. As the food applicable to the present invention, any food can be applied regardless of solid or liquid as long as it is a food in which the growth of lactic acid bacteria and other microorganisms poses a problem in storage.

[0023]

In accordance with the present invention, chitosan and silver are provided on the surface of the container that comes into contact with the food, so that the food in which the growth of lactic acid bacteria and other microorganisms is a storage problem can be economically stored.

[0024]

【Example】

(Example 1) A detailed description will be given with reference to the drawings. FIG. 4 is an example of producing a laminate provided with chitosan and silver by a coextrusion method.

Polyethylene (PE, 55 μm) 5 / chitosan 10% via a co-extrusion method on a K-coated nylon film (KNy, 15 μm) 2 substrate through an adhesive layer 3 applied by the well-known gravure coating method. , Silver zeolite 10% (silver substitution rate 40%) kneaded polyethylene (chitosan 10%, silver zeolite 10% kneaded PE, 5 μm) 4
Is extruded from the T-die 13 for co-extrusion, the nip roll 7,
Using the laminate 10 formed between the first chill roll 8 and the second chill roll 9, a pouch 1 having a size of 5 cm × 8 cm (total surface area 80 cm ² ) in contact with food as shown in FIG. 1 was produced. .. FIG. 5 is a cross-sectional explanatory view of the laminated body 10. FIG. 2 is an AA cross-sectional explanatory view of the pouch of FIG.

2.0 × 10 ⁵ (pieces / m) for a plurality of pouches
10 ml of Brix liquid medium inoculated with lactic acid bacterium of 1)
Each was filled and sealed. This was preserve | saved at 30 degreeC, it opened one by one over time, and the number of bacteria was measured by the pouring method using the Brix agar medium. In addition, 5.5 × 10 ^{5 for} multiple pouches
10 ml of glucose peptone liquid medium inoculated with (yeast / ml) baker's yeast was filled and sealed. This is 30 ℃
, The cells were sequentially opened, and the number of bacteria was measured by the pour method using potato dextrose agar medium.

Comparative Example 1 By a coextrusion method, a K-coated nylon film (KNy, 15 μm) 2 substrate was coated with
Polyethylene (PE, 55 μm) 5 / chitosan 10% kneaded polyethylene (chitosan 10% kneaded PE, 5 μm) through the adhesive layer 3 applied by the well-known gravure coating method.
m) 4 is extruded from a co-extrusion T-die 13, and a laminate 10 formed through a nip roll 7, a first cooling roll 8 and a second cooling roll 9 is used, and one side in contact with food, as shown in FIG. Is 5 cm x 8 cm (total surface area 80c
m ² ) pouch 1 was produced. FIG. 5 is a cross-sectional explanatory view of the laminated body 10. 2 is a cross-sectional view of the pouch of FIG. 1 taken along the line AA '.

2.0 × used in Example 1 for multiple pouches
Brix liquid medium inoculated with 10 ⁵ (cells / ml) of lactic acid bacteria was filled in an amount of 10 ml and sealed. This was preserve | saved at 30 degreeC, it opened one by one over time, and the number of bacteria was measured by the pouring method using the Brix agar medium.

In addition, a plurality of pouches were filled with 10 ml of a liquid medium of bute sugar peptone inoculated with 5.5 × 10 ⁵ (cells / ml) of baker's yeast used in Example 1 and sealed. This was preserve | saved at 30 degreeC, it opened one by one over time, and the number of bacteria was measured by the pouring method using the potato dextrose agar medium.

(Comparative Example 2) By a coextrusion method, a K-coated nylon film (KNy, 15 μm) 2 substrate was coated with
Polyethylene (PE, 55 μm) 5 / silver zeolite 10 through the adhesive layer 3 applied by the well-known gravure coating method
% (Silver substitution rate 40%) kneaded polyethylene (PE with silver zeolite 10% kneaded, 5 μm) 4 for co-extrusion T-die 1
3 is used, and a laminate 10 formed through the nip roll 7, the first cooling roll 8 and the second cooling roll 9 is used, and one side in contact with food as shown in FIG.
The pouch 1 having a cm (total surface area 80 cm ² ) was prepared. FIG. 5 is a cross-sectional explanatory view of the laminated body 10. 2 is shown in FIG.
It is an AA cross-section explanatory drawing of the pouch of FIG.

2.0 × used in Example 1 for multiple pouches
Brix liquid medium inoculated with 10 ⁵ (cells / ml) of lactic acid bacteria was filled in an amount of 10 ml and sealed. This was preserve | saved at 30 degreeC, it opened one by one over time, and the number of bacteria was measured by the pouring method using the Brix agar medium.

Further, 10 ml of a glucose peptone liquid medium inoculated with 5.5 × 10 ⁵ (cells / ml) of baker's yeast used in Example 1 was filled in a plurality of pouches and sealed. This was preserve | saved at 30 degreeC, it opened one by one over time, and the number of bacteria was measured by the pouring method using the potato dextrose agar medium.

(Comparative Example 3) A film obtained by forming polyethylene (PE, 60 μm) on a substrate of a K-coated nylon film (KNy, 15 μm) by an extrusion coating method and having one side in contact with food of 5 cm × 8 cm ( A pouch having a total surface area of 80 cm ² ) was produced. A plurality of pouches was filled with 10 ml of Brix liquid medium inoculated with 2.0 × 10 ⁵ (cells / ml) of lactic acid bacteria used in Example 1 and sealed. Store this at 30 ℃, open sequentially over time,
The number of bacteria was measured by the pour method using Brix agar medium.

A plurality of pouches was filled with 10 ml of glucose peptone liquid medium inoculated with 5.5 × 10 ⁵ (cells / ml) of baker's yeast used in Example 1 and sealed. This was preserve | saved at 30 degreeC, it opened one by one over time, and the number of bacteria was measured by the pouring method using the potato dextrose agar medium. The results of these measurements are shown in Table 1.

[0035]

[Table 1]

(Example 2) As shown in FIG. 6, polyethylene (PE, 40 μm) 12 was formed on the base material of K-coated stretched polypropylene film (KOPP, 20 μm) 11 through the adhesive layer 3 by the extrusion coating method. The formed film 16 was produced. At this time, the dusting machine 14 drops the chitosan 15 and the chitosan 15 is placed on the first cooling roll 8.
Was attached and the melted polyethylene 12 was cooled on the cooling surface to which the chitosan 15 was attached, whereby the chitosan 15 was provided on the surface of the polyethylene 12 as shown in FIG. 7. The applied amount of chitosan was 1 g / m ² . (Film A)

Similarly, the K-coated stretched polypropylene film (KOPP,
20 μm) 11 on which a polyethylene (PE, 40 μm) 12 was formed via an adhesive layer 3 to prepare a film 16. At this time, dropping the silver zeolite having a silver substitution rate of 20% with a dusting machine 14 to deposit the silver zeolite on the first cooling roll 8 and cool the melted polyethylene 12 on the cooling surface to which the silver zeolite is attached. In the same manner, silver zeolite was applied onto the surface of polyethylene 12 in the same manner. The applied amount of silver zeolite was 1 g / m ² . (Film B)

The film A and the film B were attached to each other, and the polyethylene surface having the chitosan and silver zeolite attached thereto was the surface in contact with the contents as shown in FIG.
One side in contact with the contents is 5cm x 8cm (total surface area 80c
to prepare a pouch of m ^2).

The koji used for radish pickle was diluted 10 times with sterilized distilled water and filtered with sterilized gauze to remove the solid matter to obtain an extract solution, and 10 ml of this solution was added to this pouch. Filled and sealed. A plurality of these pouches were prepared, stored at 30 ° C., sequentially opened over time, and the number of bacteria was measured by the pour-in method using potato dextrose agar medium and Brix agar medium.

Comparative Example 4 By the extrusion coating method
, K-coated stretched polypropylene film (KOPP,
Polyethylene (PE, 40μ) on a substrate of 20μm
m) formed film (film C), contact with food
One side is 5 cm x 8 cm (total surface area 40 cm ²) Tona
And the film A on the other side
5 cm x 8 cm (total surface area 40 cm)²) Pow
Chi was made.

10 ml of the extract used in Example 2 was added to this.
Filled and sealed. Make several pouches at 30 ℃
, The cells were sequentially opened, and the number of bacteria was measured by the pour method using a potato dextrose agar medium and a Brix agar medium.

(Comparative Example 5) In film C, one side in contact with food is 5 cm x 8 cm (total surface area 40 cm ² ), and the other side is in film B, 5 cm x 8 in side in contact with food.
A pouch having a cm (total surface area of 40 cm ² ) was prepared.

10 ml of the extract used in Example 2 was added to this.
Filled and sealed. Make several pouches at 30 ℃
, The cells were sequentially opened, and the number of bacteria was measured by the pour method using a potato dextrose agar medium and a Brix agar medium.

(Comparative Example 6) With the film C, a pouch with one side in contact with food of 5 cm × 8 cm (total surface area 80 cm ² ) was prepared.

10 ml of the extract used in Example 2 was added to this.
Filled and sealed. Make several pouches at 30 ℃
, The cells were sequentially opened, and the number of bacteria was measured by the pour method using a potato dextrose agar medium and a Brix agar medium. The results of these measurements are shown in Table 2.

[0046]

[Table 2]

(Embodiment 3) With the apparatus shown in FIG. 8, polypropylene (PP) 17 melted by heat is extruded from the T die 13 so that the final thickness becomes 1.5 mm, and the first cooling roll 8 and the nip roll 7 are extruded. Before being solidified to form a sheet by being cooled by P, the powder P is heat-melted by P between the T die 13 and the first cooling roll 8 and the nip roll 7.
Chitosan 15 was sprinkled on P17, cooled by the first cooling roll 8 and the second cooling roll 9, and solidified, and the chitosan 15 was applied onto the polypropylene sheet 17 as shown in FIG.

The amount of chitosan applied at this time was 3 g / m ² . Using this sheet, a cup-shaped container having an inner volume of 220 ml as shown in FIG. 3 was prepared by a vacuum forming method so that the surface to which chitosan was applied was the surface in contact with food. (Hereinafter referred to as cup A.) A lid material for winding which is made of aluminum and has a silver layer (average thickness 0.07 μm) provided on the surface in contact with food by a vapor deposition method was prepared. (Lid A)

Into this cup A was placed 135 g of purple leaf pickles made of cucumber, etc., filled with pickle juice, sealed with a lid material A by a winding method so that no air bubbles remained, and stored at room temperature. Occurrence of blisters and the like was inspected with time, and the taste was inspected by sequentially opening.

(Comparative Example 7) 135 g of purple leaf pickles used in Example 3 were placed in cup A, filled with pickle juice, and a normal aluminum lid material (lid material B) was used so that no bubbles remained. It was sealed by a wrapping method and stored at room temperature. Occurrence of blisters and the like was inspected with time, and the taste was inspected by sequentially opening.

(Comparative Example 8) From a PP sheet having a thickness of 1.5 mm, an internal volume of 22 was obtained by a vacuum forming method as in Example 3.
A 0 ml cup-shaped container was prepared. (Cup B) 135 g of purple leaf pickles used in Example 3 were placed in this cup B, filled with pickle juice, sealed with a lid material A by a winding method so that no air bubbles remained, and stored at room temperature. .. Occurrence of blisters and the like was inspected over time, and the palate was sequentially opened to inspect the taste.

(Comparative Example 9) 135 g of purple leaf pickles used in Example 3 were placed in cup B, filled with pickled juice, and sealed with a lid material B by a winding method so that no bubbles remained, and the mixture was kept at room temperature. Saved in. Blisters and the like were inspected over time, and the taste was inspected by sequentially opening.

As a result, the purple leaf pickles of Example 3 had no abnormal appearance such as blister until 10 days after storage (not carried out thereafter), and there was no change in taste and aroma compared to those before the start of storage. However, the products produced in Comparative Examples 7 and 9 had a blister in the cup after 2 days of storage, and the contents had a strong offensive odor and could not be eaten. The product prepared in Comparative Example 8 had a slight blistering after storage for 3 days, had a bad taste and a bad odor when opened and ate, and could not withstand edible food, and the storage test thereafter was stopped.

[0054]

As described above, as shown in the examples, the storage period can be extended only by packaging the food containing lactic acid bacteria and other microorganisms, which is a problem in storage. Example 1 is an example of a container and a storage method capable of inhibiting the growth of lactic acid bacteria and yeast simply by packaging them in the same container. Example 2 is an example of a container and a storage method capable of simultaneously inhibiting the growth of lactic acid bacteria and other microorganisms only by packaging. (Bacteria that form colonies on Brix agar are considered to be lactic acid bacteria, and bacteria that form colonies on potato dextrose agar are considered to be fungi.) In Example 3, the pickled foods in which the growth of lactic acid bacteria and yeast becomes a storage problem. On the other hand, it is an example showing that the container and the storage method according to the present invention are effective.

In addition to the above, the container and the storage method according to the present invention can be applied to the storage of syrup, fruit juice, etc., where the growth of lactic acid bacteria and other microorganisms poses a storage problem. The method of applying chitosan and silver in any of Examples 1, 2, 3, and 4 showed a preservation effect, and the container used in the present invention was found in any of the applying methods. It could be manufactured. In addition, the storage method according to the present invention can achieve the object only by packaging, and therefore, it is not necessary to change the conventional manufacturing process, which is very economical.

[0056]

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a container of the present invention.

FIG. 2 is a cross-sectional view showing a section taken along line AA ′ in FIG.

FIG. 3 is a sectional view showing another embodiment of the container of the present invention.

FIG. 4 is a schematic explanatory view showing a step of forming a chitosan-kneaded laminated film on a substrate via an adhesive by a coextrusion method.

5 is an explanatory cross-sectional view of the laminated body 10 manufactured according to FIG.

FIG. 6 is a schematic explanatory view showing a step of applying chitosan by an extrusion coating method.

7 is an explanatory cross-sectional view of the laminated film manufactured according to FIG.

FIG. 8 is a schematic explanatory view showing a step of extruding a resin melted from a T-die to give chitosan.

9 is an explanatory cross-sectional view of the chitosan-added film manufactured by FIG.

FIG. 10 is a sectional view showing another embodiment of the container of the present invention.

FIG. 11 is an explanatory cross-sectional view showing a lid member manufactured in Example 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pouch 2 ... K coat nylon film 3 ... Adhesive layer 4 ... Chitosan and silver zeolite kneading polyethylene 5 ... Polyethylene 6 ... Layer provided with chitosan 7 ... Nip roll 8 ... 1st cooling roll 9 ... 2nd cooling roll 10 ... Laminated body 11 ... K-coated stretched polypropylene film 12 ... Molten polyethylene 13 ... T die 14 ... Powder shaving machine 15 ... Chitosan 16 ... Chitosan imparting film 17 ... Molten polypropylene 18 ... Silver zeolite 19 ... Aluminum 20 ... Silver vapor deposition layer

Front page continuation (72) Inventor Norio Ikeda 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (72) Inventor Shoya Sugawara 1-5-1, Taito, Taito-ku, Tokyo Topographical printing Within the corporation

Claims (2)

[Claims] 1. A method of preserving a food, characterized in that the food is filled and sealed in a container in which at least a part or all of the inner surface in contact with the contents is provided with chitosan and silver. 2. A container formed by applying chitosan and silver to at least a part or all of the inner surface in contact with the contents.