JPS63137935A - Freshness-keeping film - Google Patents

Abstract

PURPOSE:To obtain a film effective in preventing drying of packaged perishable food, exterminating decaying bacteria and effectively keeping the freshness of the food, by dyeing a polymer film containing a functional group with a metal phthalocyanine (substituted derivative). CONSTITUTION:A base film of a polymer having a functional group is dyed with a metal phthalocyanine and/or a metal phthalocyanine-substituted derivative. The polymer base film is selected from cellulosic film and polyvinyl alcohol film. The metal phthalocyanine-substituted derivative is preferably metal phthalocyanine polycarboxylic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a film suitable for preserving the freshness of foods such as vegetables, fruits, meat, seafood, and other perishable products such as flowers.

[Conventional technology]

To maintain the freshness of food, it is important to prevent it from spoiling and to prevent the moisture contained in the food from drying out. Food spoilage progresses due to the action of various spoilage bacteria, but metabolites are generated by the respiration and metabolism of the food itself.
It is known that the action of its metabolites accelerates ripening and spoilage. On the other hand, the more moisture a food contains, the more likely it is to spoil. Therefore, it is difficult to satisfy both the requirements of preventing spoilage and preventing drying. To protect food from bacterial contamination and to prevent it from drying out, it is sometimes sealed with plastic film. Such treatment also helps prevent spoilage for some foods. However, this method is not necessarily effective in preventing spoilage if the food is contaminated with bacteria even if it has just been harvested. In fact, it is often more difficult to putrefy when exposed to the air. Additionally, wrapping food in breathable material such as paper or cloth is often helpful in slowing down the process of spoilage, but it does not prevent food from drying out, resulting in a loss of freshness.

[Problem that the invention seeks to solve]

2, it is difficult to delay spoilage without drying food, and to date, there has been no film with a freshness-preserving function.

The present invention enables packaging of various foods and perishables.
Alternatively, the present invention provides a film that not only prevents drying but also has a freshness retaining function to prevent spoilage by being mixed with perishable products.

[Means for solving problems]

The present inventors focused on and studied the effects of biological enzymes on the ability to eliminate spoilage bacteria and decompose metabolites generated by the respiratory metabolism of fresh products, thereby suppressing the acceleration of spoilage. As a result, we obtained the following knowledge. . That is, we have found that metal phthalocyanine and its substituted derivatives, which can be easily synthesized artificially, are excellent substances that have a catalytic action similar to that of metal porphyrin, which is a biological enzyme.

The freshness-keeping film of the present invention, which was made based on the above knowledge, is
A metal phthalocyanine or (and) a metal phthalocyanine substituted derivative is dyed onto a polymeric base film having a functional group.

The polymer base film having a functional group is, for example, a cellulose film (cellulose acetate, cellophane, etc.) or a polyvinyl alcohol film (Hinilon, etc.).

The functional groups of these base films are hydroxyl groups and acetyl groups. Modifying the base film with acid or alkali,
It is also possible to graft-polymerize a hydrophilic substance onto the surface to improve the dyeability. Furthermore, adding powders such as silica, titanium oxide, calcium carbonate, alumina, zeolite, and talc to the base film, as well as adding water absorbents and chitosan, can help improve the activity.

Triacetyl cellulose film is particularly excellent as a base film, and the dyeing properties of this film are improved by saponifying it with a mixed solution of sodium hydroxide solution and methanol. In addition, the microporous triacetyl cellulose film has an increased surface area and has a higher freshness retention function per film weight.

Metal phthalocyanine has the following structure. The substituted derivative has the following structure, in which the -X group is a hydrogen group or various substituents. Examples of the substituent include an alkyl group, a substituted alkyl group (e.g., chloromethyl group), a halogen group, a nitro group, an amino group, an azo group, a thiocyanate group, a carboxyl group, a carbonyl chloride group, a carboxylamide group, a nitrile group,
In addition to hydroxyl groups, alkoxyl groups, phenoxydyl groups, sulfonic acid groups, sulfonyl chloride groups, sulfonamide groups, thiol groups, alkyl silicon groups, vinyl groups, amine salts, quaternary ammonium groups or their salts, pyridine groups and their derivatives, Examples include salts thereof, and the substituents are not limited to one type of group, but may be substituted with different groups.

Since metal phthalocyanine has a planar structure, molecules tend to associate with each other. When the molecules associate with each other, the metal ion M, which is the center of catalytic activity, is covered and the catalytic activity is weakened. From this point of view, a metal phthalocyanine polycarboxylic acid (a part of the -X group in the formula 1 is a carboxyl group) which is a metal phthalocyanine substituted derivative is more preferable. That is, in metal phthalocyanine polycarboxylic acid, the carboxyl ions are electrically repelled, making it difficult for molecules to associate, and the carboxyl group causes steric hindrance, making it difficult to associate. Therefore, the metal ion M, which is the center of catalytic activity, can be maintained in an exposed state, and the catalytic activity becomes high. Furthermore, in terms of dyeability to the base film, the metal phthalocyanine polycarboxylic acid has excellent dyeability due to the electrostatic action of carboxyl ions. The more the metal phthalocyanine polycarboxylic acid has metal phthalocyanine dicarboxylic acid, metal phthalocyanine tetracarboxylic acid, and metal phthalocyanine octacarboxylic acid, the more carboxyl groups there are, the less molecular association occurs, and the higher the catalytic activity. Preferred is metal phthalocyanine tetracarboxylic acid represented by the following formula (1) or (2
) is a metal phthalocyanine octacarboxylic acid shown in the formula.

HOOC
For example, Fe, Go, Mn, Ti, V, Ni, Cu,
Zn, No., W, and O3 can be used. Preferably, it is Fe or CO, or a mixture of Fe and CO.

The larger the amount of metal phthalocyanine etc. dyed on the base film, the better the freshness-keeping function tends to be, but there is a limit to the amount that can be dyed. If the amount is less than 0.001% by weight, the freshness preservation function is hardly exhibited. Further, dyeing cannot be carried out if the amount exceeds 20% by weight. Preferably it is 0.5 to 10% by weight.

The method for manufacturing the freshness-keeping film configured as described above is as follows:
A solution of metal phthalocyanine or the like is used as a dye bath, and the base film is immersed in it to be dyed. A fixing treatment is performed to further remove the dyed metal phthalocyanine and the like. When the metal phthalocyanine or the like is a metal phthalocyanine polycarboxylic acid, the fixing treatment is performed after dyeing, for example, with a copper sulfate solution, a cupric chloride solution, a cardim chloride solution, or the like. Then, a chelate bond of copper or calcium occurs between the carboxyl group of the metal phthalocyanine polycarboxylic acid and the base film, making it difficult for the metal phthalocyanine polycarboxylic acid to separate.

[Effect]

The freshness-preserving film of the present invention has dyed metal phthalocyanine, etc., which has a catalytic action similar to that of biological enzymes, that is, biological enzymes eliminate spoilage bacteria and decompose metabolites generated by respiratory metabolism of fresh products. It has the effect of suppressing the promotion of The catalytic action similar to biological enzymes is the action as a redox catalyst, in which the central metal M of metal phthalocyanine or the like gives and receives electrons, and has, for example, an action similar to oxidase, an action similar to peroxidase, and an action similar to oxygenase. This prevents the packaged food from spoiling.

Since metal phthalocyanine and the like are dispersed and dyed in the functional groups of the base film at the molecular level, steric hindrance by the polymer chains of the base film and association of molecules such as metal phthalocyanine are less likely to occur. Therefore, the metal ion M, which is the center of catalytic activity, can be maintained in an exposed state, and the catalytic action can be fully exerted.

Furthermore, since the base is a plastic film, it is possible to prevent the packaged food from drying out.

[Example] Hereinafter, a freshness-keeping film to which the present invention is applied will be manufactured according to the following Examples, and its performance will be evaluated.

Example 1゜ Triacetyl cellulose film (thickness 0.018 mm, 5 cm x 5 cm) was used as a base film at 40%
After saponifying the surface by immersing it in a mixed solution of 10 ml of NaOH and 60 ml of methanol at 40°C for 5 minutes, it is thoroughly washed with water. On the other hand, add 0.2g of lN-NaOH to 10ml.
of iron phthalocyanine octacarboxylic acid and 0.85 g of N
Dissolve a2SO4 and prepare a dye bath.

The triacetyl cellulose film whose surface has been saponified as described above is immersed in this dye bath at 60° C. for 10 minutes for dyeing. By fixing it in 1NHCl, washing with water, and drying, a freshness-preserving film dyed with iron phthalocyanine octacarboxylic acid is obtained. The amount of iron phthalocyanine octacarboxylic acid dyed was determined to be 4.5% by weight from the determination of iron using an atomic absorption spectrophotometer.

Example 2゜ A triacetylcellulose film whose surface was saponified in the same manner as in Example 1 was dip-dyed in the same dye bath under the same conditions, and then fixed with I N CLICI 2, washed with water, and dried to obtain a freshness-retaining film. . The surrounding carboxyl groups of the dyed iron phthalocyanine octacarboxylic acid form a copper salt.

Example 3 After pulverizing 1.39 g of chitosan in a ball mill for 24 hours, 12.58 g of triacetylcellulose and CH2Cl
287.5 g was added, and the mixture was further mixed and dissolved in a ball mill for 5 hours. A glass film was cast onto the obtained doped glass plate and dried with a dryer to obtain a base film with a thickness of 20 Jj. The base film was dyed with iron phthalocyanine octacarboxylic acid in the same manner as in Example 1 to produce a freshness-keeping film.

Example 4 A porous thin film filter of triacetylcellulose is used as the base film. Further, cobalt phthalocyanine tetracarboxylic acid is used as the metal phthalocyanine polycarboxylic acid. A freshness-keeping film was produced under the same conditions as in Example 1 except for the above.

Example 5 A dye bath is prepared by dissolving 0.2 g of iron phthalocyanine tetracarboxylic acid and 0.85 g of Na2 SO4 in 10 ml of N-NaOH. Add cellophane film (thickness 0.02n+m, 5cm x 5cm) as a base film to this dye bath.
c+w) at 60°C for 5 minutes. l it
By fixing in N-HCl, washing with water, and drying, a freshness-preserving film dyed with iron phthalocyanine tetracarboxylic acid is obtained.

The results of testing the number of viable bacteria over time after packaging food with the freshness-preserving film manufactured according to each example described in 1. The results of testing the number of viable bacteria are shown in Tables 1 to 3 below. The food in Table 1 was boiled rice and was stored at room temperature (20°C), the food in Table 2 was egg rolls and was stored in the refrigerator (5°C), and the food in Table 3 was kamaboko and was stored in the refrigerator (5°C). Note that commercially available food wrap films are made of polyvinylidene chloride.

Table 1 Table 2 (Number of viable bacteria/g, food omelet, stored at 5°C)
Table 3 (Number of viable bacteria/g, food kamaboko, stored at 5°C) Table 4 below shows the state of decay of the food packaged with the film produced in Example 1 (Example), and This figure shows the results of observing the state of decomposition of food wrapped with a commercially available food wrap film (comparative example) over time. Among the foods, shellfish radish, cooked rice, and chikuwa were stored at room temperature (20°C), and pork was stored in the refrigerator (5°C).

(Leaving space below) Table 4 It should be noted that simply placing this freshness-preserving film on the bottom of a corrugated pole box without having to package the food was sufficient to perform its function, and placing the food therein was helpful in preserving freshness.

〔Effect of the invention〕

As explained above, the freshness-preserving film to which the present invention is applied can eliminate spoilage bacteria through the catalytic action of metal phthalocyanine, etc. similar to biological enzymes, and promote spoilage by decomposing metabolites generated during respiratory metabolism of fresh products. There is a function to suppress

Moreover, since metal phthalocyanine and the like are dispersed and dyed at the molecular level, they can fully exhibit their catalytic action. Furthermore, since metal phthalocyanine and the like act as catalysts, they are not consumed, and the film's freshness-keeping function is permanent and has the economical advantage of being able to be used repeatedly.

Furthermore, since the base is a polymeric film, packaged foods and perishables will not dry out, which is also advantageous for maintaining freshness.

Claims (1)

[Scope of Claims] 1. A freshness-preserving film characterized in that a polymeric base film having a functional group is dyed with a metal phthalocyanine or/and a metal phthalocyanine substituted derivative. 2. The freshness-keeping film according to claim 1, wherein the functional group-containing polymeric base film is a cellulose film or a polyvinyl alcohol film. 3. The freshness-keeping film according to claim 1, wherein the metal phthalocyanine substituted derivative is a metal phthalocyanine polycarboxylic acid.