JP2604661B2 - Manufacturing method of chitosan solution, food treated with the solution and food packaging material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing chitosan into a solution, and more particularly to a method for producing a chitosan solution suitable for use in food-related products and a method for producing the same. The present invention relates to a food and a related product such as a food packaging material treated with the obtained chitosan solution.

[0002]

2. Description of the Related Art For example, when chitosan is treated on a base material such as paper, the wet strength of the base material is improved. Further, when the base material is used as a food packaging material, water vapor from the packaged object is reduced. Can be transmitted, but the fragrance etc. can be retained, so that it is possible to obtain food with intermediate moisture while suppressing deterioration in quality. It is known for use in casings for filling goods. In addition, it is known that the processed product can be used for various uses and products such as medical materials, bandages, plasters, disposable diapers, agricultural materials in fields other than the food packaging materials as described above. Numerous proposals have been made on various processed products and methods for producing the same, including, for example, JP-A-1-174699 and JP-A-2-127596.

[0003] The when utilizing chitosan for various products like, it is necessary to the solution of dissolved chitosan as raw material, as a solvent for dissolving the chitosan has conventionally generally Various acidic liquids such as organic acids or inorganic acids, for example, aqueous solutions of acetic acid, lactic acid, citric acid, malic acid, tartaric acid, hydrochloric acid, nitric acid and the like are used. In this case, organic acids such as acetic acid, lactic acid, and citric acid are used for those used for applications such as food packaging materials.

[0004] In addition, chitosan can be used in a variety of products, but as described above, since acid is conventionally used as a means for dissolving chitosan, for example, for the purpose of preserving food quality, etc. If the food is directly treated with the dissolved chitosan solution, the original taste of the food is impaired, and thus, the direct use of the chitosan solution for the food has not yet been performed. Therefore, in the past, the use of chitosan solution has been related to food packaging materials as a related field of food, particularly about the casing for filling processed meat products as described above, and is often used for products other than food-related fields. The purpose is.

[0005]

As described above, it is common sense to use various acidic aqueous solutions as a means for dissolving chitosan, and the concentration of the acid used as a solvent is usually Requires about the same concentration as chitosan
Since that, be brought into close contact treated chitosan solution dissolved by weight such acids in the food there is the problem that undesirable. Also, when such a chitosan solution is processed into a material such as paper, the processed paper may still have the acid used for dissolving the chitosan remaining on the surface, so that it is in direct contact with the surface of the food. However, there is a problem that it is not practically suitable for use such as a packaging material.

[0006] Therefore, although it has been proposed to use a chitosan solution for applications such as food packaging materials, it is a fact that the solution has not been produced as an actual product, but only at the stage of trial production. Furthermore, when treated with chitosan solution to paper substrate, after processing the chitosan solution, it requires a sure step of neutralization of the acid by the alkaline before drying, require such post-treatment It is difficult to say that this is preferable in terms of cost from the viewpoint of manufacturing a food packaging material.

As described above, in consideration of the problem of dissolving chitosan with an acid as a conventional technique, a problem to be solved is whether chitosan can be dissolved using a solvent other than an acid. Or, even if an acid is used, how can the amount of acid used be reduced,
That's what it means. In this case, be dissolved by eating for <br/> solvent other than the acid chitosan, even not be solved yet at present, if the resulting chitosan solution by reducing the amount of acid used, This is a significant advantage as it will be widely available in the field of food and its packaging.

[0008]

SUMMARY OF THE INVENTION The present invention substantially reduces the amount of an acid used in a conventional method in view of the above-mentioned problem of dissolving chitosan with an acid. Accordingly, it is an object of the present invention to provide a method for obtaining a chitosan aqueous solution, a food using the chitosan solution obtained by this method, and a product related thereto.

[0009] As a specific means for achieving the above object, the invention of claim 1 relates to a method for producing a chitosan solution, comprising contacting a chitosan raw powder with a non-equilibrium low-temperature plasma, A chitosan aqueous solution by imparting easy solubility to the solution.
The invention of claim 2 relates to a food packaging material using the chitosan aqueous solution obtained by the above-mentioned treatment, wherein the aqueous solution is treated into a packaging material such as paper. Further, the invention of claims 3 and 4
The present invention relates to a food using the chitosan aqueous solution obtained by the above treatment, wherein the aqueous solution is treated as a film on the surface of the food.

In terms of the solubility of chitosan, chitosan has a crystal structure, molecules exhibit rigidity derived from strong hydrogen bonds, and the greatest drawback is the difficulty of handling such as insolubility and infusibility. . However, chitosan has an amino group in its constituent residue, and the amino group easily reacts with “acid” to form “salt”. As described above, it is common sense to use an “acid” to obtain an aqueous chitosan solution, but the conformation of this salt forms a helical structure, and all amino groups are located outside the molecular chain of a cylindrical structure. And the acid is further bound to its outside.

The conformation of the molecular chain has only two types, and has a well-extended structure, embodying the rigidity of the chitosan molecule. Chitosan salt (acidic aqueous solution)
Has formed a gel. In other words, the molecular chains of the chitosan salt assemble, form a thicker and longer bundle, and subsequently form a junction region by partial micelle formation. They build vesicles, which contain a collection of water molecules. This can be said to be a matrix structure swollen with water.

Considering the problem of imparting hydrophilicity to chitosan and reducing the amount of acid used, the amino group of chitosan is subjected to regioselective chemical modification by various methods. Are known, but all of these methods are reactions by chemicals, and require a complicated method, and it is necessary to separate the obtained target substance from by-products. Therefore, as a result of examining measures to reduce the amount of acid used by a means other than the reaction with a chemical against such a problem, the present inventors have found that chitosan has a non-equilibrium
It was confirmed that hydrophilicity can be imparted by modification by physical treatment such as contact with low-temperature plasma.

[0013]

According to the treatment method of the present invention, flake-form chitosan is powdered, and the chitosan powder to be treated is sprayed with a suitable amount of water to impregnate the chitosan, and is brought into contact with non-equilibrium low-temperature plasma. When non-equilibrium low-temperature plasma is brought into contact with the chitosan powder to be treated in this way, the hydrogen bond of the chitosan molecule relaxes due to the reaction between the activated oxygen generated in the plasma atmosphere and the subsequent radical intermediate. The rigidity is reduced, or OH is applied to impart hydrophilicity.

Therefore, the chitosan powder treated as described above has improved water-solubility, and is easily dissolved by a very small amount of acid, for example, lactic acid which is not so problematic even when used in foods. Obtainable. As a result, even if the chitosan aqueous solution obtained by this method is directly adhered to food directly, or if it is applied to materials such as paper for wrapping food, there is no risk of causing the conventional problem of the inhibition of taste due to acid. It hardly occurs.

[0015]

Embodiment 1 The contents of the present invention will be described in detail below. The invention of claim 1 relates to a method for producing an aqueous solution of chitosan, in which a flake-form chitosan raw material is preliminarily pulverized into a powder to obtain a powder having a large reaction surface area with respect to volume, and an appropriate amount of the chitosan powder to be treated. The chitosan powder to be treated is stored in a low-temperature plasma generating vessel equipped with a stirrer.

As a gas for generating the non-equilibrium plasma, gases such as air, oxygen, and nitrogen are used. In the present invention, in addition to flowing these gases into the container, the pressure in the container is reduced. Then, a vacuum treatment method using water vapor evaporating into the container from water previously impregnated into the chitosan powder to be treated is also adopted.

After the chitosan powder to be treated is stored in a low-temperature plasma generating container, the container is filled with 5 to 20 torr.
The pressure is reduced to a certain degree, and a glow discharge is performed by a discharge electrode provided above the inside of the container while rotating the stirring device in the container, and the non-equilibrium low-temperature plasma generated in the container is brought into contact with the chitosan powder to be treated. When the non-equilibrium low-temperature plasma is brought into contact with the chitosan powder to be treated in this way, the hydrogen bond of the chitosan molecule relaxes due to the reaction between the activated oxygen generated in the plasma atmosphere and the subsequent radical intermediate, and the rigidity is reduced. OH is imparted or hydrophilicity is imparted by applying OH.

This reaction is performed on the solid surface by gas, and as described above, the reaction surface area is increased by pulverization of the chitosan to be treated, so that the reactant is mainly obtained on the surface layer of the chitosan powder. Therefore, by stirring the chitosan powder to be treated in the container, the powder is sequentially brought into contact with the plasma, and a uniform reaction result is obtained.

The above reaction finally produces carbon dioxide gas and water, which are discharged out of the system. Therefore, when this reaction is completed, the material balance is theoretically zero, and there is no fear that the chemicals remain in the material to be treated unlike the conventional treatment. In addition, since the above-mentioned reaction occurs from a gas to a solid, there is no problem such as wetting of chitosan as an object to be treated, and therefore there is no need to perform any post-treatment. The plasma contact time in the container is desirably about 120 to 600 minutes.

Next, the chitosan powder, which has been treated as described above, is dissolved using a small amount of acid, preferably lactic acid. As the chitosan aqueous solution obtained by the above processing, among the examples using gases such as air, oxygen, and nitrogen in addition to vacuum processing, those treated with oxygen gas have the highest quality as compared with those of other examples. Met.

[0021]

[Table 1]

Comparative Experimental Example 1 First, as shown in Samples 1 and 2 in Table 1, a flaky chitosan raw material ("Flownac" manufactured by Kyowa Technos Co., Ltd.) was passed through a 6 to 10 mesh shifter. 200 g of the chitosan powder to be treated was dissolved and treated with 0.5 to 2% lactic acid in order to produce a chitosan aqueous solution having a concentration of 2% without performing the modification treatment by contacting with non-equilibrium plasma.

Next, as shown in Samples 3 and 4 in Table 1,
Without bringing the same chitosan powder to be treated into a humidified state,
It was housed in a commercial AC operated discharge vessel equipped with a 4 liter glass distillation bottle, and the pressure inside the vessel was reduced to 5 torr.
And stir the chitosan powder to be treated 8 to 9
Glow discharge was applied for 120 minutes with a current of mA.

Sample 3 was subjected to vacuum processing without supplying a gas for generating plasma during the discharge. Sample 4 was processed by supplying nitrogen gas as a gas for plasma generation at a rate of 2 L / min, and Sample 6 was processed by supplying air at a rate of 3 L / min. Furthermore, after performing the above-mentioned plasma contact treatment, in order to produce a 2% concentration chitosan aqueous solution using the chitosan powder to be treated of each sample, 0.5% lactic acid (“Kansho lactic acid 45” manufactured by Musashino Chemical Co., Ltd.) was used. % ").

[0025]

[Table 2]

[0026]

[Table 3]

Comparative Experimental Example 2 As shown in Samples 6 to 8-3 in Table 2 and Samples 9 to 9-3 in Table 3, the same chitosan powder to be treated was ground to such an extent that it passed a 10-mesh shifter. Water was sprayed on 200 g and humidified by about 10%, and the chitosan powder was subjected to a discharge treatment in the discharge vessel for 120 to 600 minutes. Sample 6 was processed by supplying air at a rate of 3 L / min as a gas for plasma generation during discharge.

In Samples 7 and 8-3, water vapor evaporating into the container from water previously impregnated with the chitosan powder to be treated by reducing the pressure in the container was used without supplying gas. In Samples 9 to 9, oxygen gas was supplied as a gas for plasma generation at a rate of 1.5 liter / min. Further, after performing the above-mentioned plasma contact treatment, a 2% concentration of chitosan is
In order to prepare aqueous solutions, dissolution treatment was performed using 0.5% to 1% of the same lactic acid as described above.

Example 2 In the chitosan aqueous solution obtained by the above-mentioned treatment, the amount of acid used for dissolution was reduced to about half or less of that in the case of a conventional method.
In addition, since the pH can be made close to neutral, it is suitable from the viewpoint of commercial properties, and as a result, it is suitable for obtaining food packaging paper using this solution. Example 2 relates to food wrapping paper obtained by treating the chitosan solution into paper. This food wrapping paper is suitable for packaging various foods that contain water or have a wet surface, such as fish and shellfish and processed products thereof, meat and processed products thereof, vegetables and fruits. . Further, as the paper for treating the chitosan solution, wrapping paper having a newspaper-like property having a particularly good water absorption and a small amount of a synthetic agent is suitable, and the chitosan solution is applied to one or both sides of this type of paper. Apply and leave in air or dry with warm air.

When the food is sealed and packaged with a wrapping paper having a coating obtained by applying the chitosan solution and dried, low molecules such as water vapor and ethylene gas in the food are transmitted to the outside of the membrane, but an aromatic substance Those having a large molecular weight, such as alcohol, oils and fats, are retained in the film. Therefore, moisture is released from the packaged object until it equilibrates with the surrounding environment conditions such as humidity, temperature and pressure (until the equilibrium vapor pressure is reached).
Since the diffusion of the water can be maintained and a large amount of a preferable substance as a food can be retained, a food different from the dried food processed by the conventional drying method can be obtained.

Example 3 In addition, the aqueous solution of chitosan obtained by the above treatment can reduce the amount of the acid used for dissolution to about one-half or less of that obtained by a conventional method. The solution can be directly applied to food and used. Example 3 relates to a food product treated with the chitosan solution described above. In this case, as a mode of treating the chitosan solution into food, there are an indirect coating method in which the food is first wrapped with a suitable paper and then applying the chitosan solution, and a direct coating method in which the chitosan solution is immersed in the food surface. There are cases.

In the above-mentioned embodiment, in the case of the indirect coating method, a seafood product, for example, a scallop column meat, is treated with a paper suitable for treating a chitosan solution having the properties shown in Example 2 above. Wrap and immerse or apply the wrap in a chitosan solution. At that time, the wrapping paper that is moistened by immersion or application of the chitosan solution is pressed against the surface of the food, and the chitosan solution is well filled in the gap between the paper and the paper while preventing a gap from being formed between the paper and the food. Treat to penetrate. Next, the packaged content is subjected to a drying process under a temperature condition (sunshine, hot air drying, or the like) at which the product temperature does not rise and quality deterioration does not occur.

In the case of the above direct coating method,
Foods such as fruits, meat hams and sausages, and dried fish are directly immersed in the chitosan solution or are evenly attached to the surface. In this case, as a separate method , a chitosan solution having a concentration of about 2 to 3% mixed with 2% calcium lactate is used as a first liquid, and the food is first immersed in the first liquid.
After draining, it is immersed again in a second liquid composed of a 3% aqueous solution of sodium alginate, and then dried under the same conditions as described above.

As described above, in the case of the direct coating method, by treating with the first liquid and the second liquid, the film formed on the surface exhibits a thick and strong solidified state, and the subsequent drying treatment and product it is possible to storage made reliable. In this case, when the liquid adhering to the surface of the food is dried to form a film, it is necessary to take care not to cause scratches such as pinholes or peeling on the film.

[0035]

The dissolution state of the aqueous chitosan solution obtained in the experiment of Example 1 is as follows: Samples 7 to 8 in Table 2 by vacuum treatment and Samples 9 to 9 in Table 3 The sample treated with oxygen gas was the best in comparison with those of the other examples. As the processing time is about 180 minutes as such sample 7, the reaction it is believed et al are not caused very little seeking. this is,
Since the method of the present invention is a reaction of a gas to a solid and a reaction only at the surface of chitosan powder, it is considered that a relatively long time is required to treat rigid chitosan. Therefore, it is preferable to require a processing time of about 600 minutes as in Samples 8 to 9.

[0036] Chitosa is produced by a chemical treatment that is commonly used.
It is common sense to reduce the molecular weight when making
The aqueous solution turns brown over time. But the book
The aqueous solution of chitosan obtained by the treatment of the invention dissolves
After that, it was allowed to stand still for about 3 months in the room.
And any of the samples shown in Table 3)
No change was observed, and there was no difference in the hue of the solution.
Did not occur. That is, the chitosa of Samples 1 and 2 without treatment
Molecular weight and each of the samples 3 to 9
For each molecular weight, little change occurred (almost
Is not reduced).

Further, regarding the subsequent reaction after the reforming treatment,
When a comparative dissolution test was performed between the sample 8 and the sample 8 treated 3 days later under the same conditions, no significant difference was observed. Further, when the same comparative dissolution test was performed one week later, no significant difference was observed in the dissolution state after a lapse of 72 hours at 25 to 30 ° C.

In the invention of Embodiment 2, as a result of the experiment,
When freshly fried croquettes, freshly baked eggs, etc. were wrapped in the above wrapping paper, the water vapor was quickly dissipated, but the oil did not seep on the surface of the wrapping paper, and the form as the wrapping paper was firm. . The food packaged with the above wrapping paper is preferably stored refrigerated from the viewpoint of suppressing an increase in product temperature which causes deterioration or deterioration of the target food product. Further, in the frozen state, the contained water freezes, so that the diffusion of the water is insignificant.

Further, according to the invention of Example 3, when the wrapping paper on the surface of the scallops treated by the above-mentioned indirect coating method was peeled off after about one week, the degree of hardening due to drying was low, The feeling and taste were very good. Also,
When the meat salami sausage is manufactured by the direct coating method described above, the edible casing which can replace the synthetic resin casing in the conventional salami sausage can be obtained by the chitosan solution coated on the surface of the salami sausage, and the leaching of oils and fats can be obtained. And a good texture and taste that could not be obtained by the smoking process.

In the case of producing dried products such as fruits, vegetables, marine products, and livestock meat by the direct coating method, quality deterioration such as browning and lipid oxidation due to an increase in product temperature can be suppressed by the coating on the surface, and a dryer is required. The effect of forced drying when used and the cost savings could be expected. Moreover, it is also possible to proceed with the storage in the refrigerator or the drying process in the form of the product in parallel, and in this state, the aromatic substances and other useful components are retained, so that there is no feeling of drying out unlike conventional dry foods. Food and could be.

In Example 1, lactic acid was used to dissolve the modified chitosan powder by contact with plasma, but according to the production method of the present invention, the amount of acid used for dissolution was used. Can be greatly reduced as compared with the conventional method, and therefore, for example, acids such as ascorbic acid and citric acid can be used in addition to the lactic acid.

Claims (4)

(57) [Claims] 1. A method for producing a chitosan solution in which a raw chitosan powder is brought into contact with a non-equilibrium low-temperature plasma to obtain a chitosan aqueous solution from the treated raw powder. 2. A food packaging material treated with a chitosan solution obtained by contacting a raw chitosan powder with a non-equilibrium low-temperature plasma, and treating a chitosan aqueous solution obtained from the treated raw powder with a packaging material such as paper. 3. A food treated with a chitosan solution obtained by contacting a raw chitosan powder with non-equilibrium low-temperature plasma and treating the surface of a food packaged with paper with a chitosan aqueous solution obtained from the treated raw powder. 4. A food product treated with a chitosan solution obtained by contacting a raw chitosan powder with non-equilibrium low-temperature plasma and treating the surface with a coating of an aqueous chitosan solution obtained from the treated raw powder.