JPH01167302A - Stabilization treatment method for water-soluble chitin or chitosan - Google Patents

Abstract

PURPOSE:To enhance the quality stability of the title chitin or chitosan and suppress the quality deterioration thereof such as viscosity drop-off, discoloration, abnormal odor generation, etc., at high temperatures, by reduction treatment of a water-soluble chitin or chitosan in a homogeneous solution system. CONSTITUTION:A water-soluble chitin or chitosan (e.g., carboxylmethylchitin or chitosan, sulfated chitin or chitosan, N-glycidyl trimethylammonium chitosan) is put to reduction treatment in a homogeneous solution system to effect stabilization of said chitin or chitosan. For said reduction treatment, 0.1-20wt.% of a reduction agent such as Li or hydrogenated sodium boride is pref. used based on the chitin or chitosan, and said treatment is pref. carried out at 10-80 deg.C for 2-8hrs. The water-soluble chitin or chitosan thus obtained is useful as a drug or food.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a treatment method capable of improving the quality stability of water-soluble chitin and chitosan.

[Problems to be solved by conventional technology and invention] Water-soluble chitin and chitosan are used in pharmaceuticals and cosmetics.

It is effectively used in the field of miscellaneous goods, etc., but water-soluble chitin,
Chitosans are polysaccharides in which amino sugars are condensed with glycosidic bonds, and are thermodynamically unstable. Therefore, over the course of 1 hour, there is significant hydrolysis, removal of functional groups, and ring-opening of glucose rings. Recombination progresses, resulting in quality deterioration such as decreased viscosity, decreased solubility, formation of precipitates, and generation of colored and off-odor.

Therefore, in order to utilize water-soluble chitin and chitosan for various purposes, it is required to ensure a certain level of quality stability.

In this case, it has been confirmed that the decomposition reaction of water-soluble chitin and chitosan proceeds under high humidity conditions or when made into an aqueous solution, and this decomposition rate increases at temperatures above 40°C.

Reactions involved in this decomposition can be broadly classified into cleavage of the main chain due to thermal movement and radical reactions, decondensation of glucoside bonds, deamination reactions, amino-carbonyl reactions, and various radicals and reactions. In particular, the amino-carbonyl reaction is greatly involved. Therefore, in order to improve the quality stability of water-soluble chitin and chitosan, it is necessary to avoid each of the above reactions, especially the amino-carbonyl reaction, as much as possible.

However, until now, few methods have been proposed to effectively improve the quality stability of water-soluble chitin and chitosan; for example, Japanese Patent Application Laid-Open No. 174227/1983.

The report discloses methods for decolorizing and deodorizing chitosan, but
In this method, water-insoluble polymeric chitosan is treated in a heterogeneous system using an oxidizing agent and a reducing agent, and only the surface of the chitosan immediately after treatment is decolored and deodorized. It cannot be used as a method to prevent quality deterioration that occurs during storage.

The present invention was made in view of the above circumstances, and aims to provide a treatment method that can prevent water-soluble chitin and chitosan from deteriorating over time, especially at high temperatures, and improve their quality stability. shall be.

[Means and effects for solving the problem] In other words, the present inventors conducted intensive research to achieve the above object, and as a result, they uniformly dissolved water-soluble chitin and chitosan in an aqueous solvent, and - When water-soluble chitin and chitosan are subjected to reduction treatment in a solution system, the various reactions that cause quality deterioration mentioned above, especially the amino-carbonyl reaction, are inhibited by alcoholization of carbonyl-based impurities, resulting in reduction of water-soluble chitin and chitosan. The present inventors have discovered that the quality stability of the products is improved, and have come up with the present invention.

Therefore, the present invention provides a method for stabilizing water-soluble chitin and chitosan, which is characterized by subjecting the water-soluble chitin and chitosan to a reduction treatment in a homogeneous solution system.

The present invention will be explained in more detail below.

As described above, the method for treating water-soluble chitin and chitosan of the present invention involves reducing the water-soluble chitin and chitosan in a homogeneous solution system.

In this case, there is no limitation on the type of water-soluble chitin or chitosan, and those with various molecular weights ranging from oligomers to polymers can be used, and specifically, those exemplified below can be suitably used.

(1) A water-soluble oligomer of chitin or chitosan obtained by decomposing chitin or chitosan into a low molecular weight product (provided that the degree of polymerization of glucosamine units is greater than 1).

Such oligomers can be obtained by ordinary molecular weight reduction methods, such as nitrous acid decomposition method, formic acid decomposition method, and chlorine decomposition method (Japanese Unexamined Patent Publication No. 59-43282).

It can be obtained by enzymatic or microbial decomposition methods.

(2) Water-soluble partial arm 7-cetylated chitin with a degree of deacetylation of preferably 40 to 60%.

For example, it can be obtained by controlling the degree of deacetylation of chitin by the method disclosed in JP-A-53-47479.

(3) Chitosan salts of organic or inorganic acids; specific examples of organic acids include acetic acid, malic acid, and citric acid.

Examples of inorganic acids include ascorbic acid, etc.
Examples include hydrochloric acid, sulfuric acid, and phosphoric acid.

(4) Derivatives made water-soluble by introducing parent wood groups into chitin or chitosan. Specific examples of this include the following.

■Polyoxyethylene/polyoxypropylene chitin or chitosan [in the formula, n:>■ R,: -1-1, -COCH, or EOya+pofun J1 (however, @□=Q~5.m,= 0~5.Q+m#
o) R, knee H or +EO97-fPO砒H (however, l
it = O ~ 5 v "4" O ~ 5 * Q2 +
m,≠0)R,: -H or →EO翫・→po砒H (however, Q3=O""'5 p mz "O~5 *
Q3 +rn3≠0). Here, EO represents an oxyethylene chain and PO represents an oxypropylene chain, and the order of bonding between EO and PO does not matter; for example, first D
- PO may be added to the glucosamine skeleton, and then EO may be added, or EO and PO may be added at random. In addition, in the individual D-glucosamine skeletons that are bonded, R,, R2, R□m1. m,, ~3. Q...
Q, , Q3 may be the same or different. ] This polyoxyethylene/polypropylene glycol chitin or chitosan is produced by adding chlorohydroxyethylene, chlorohydroxypropylene, ethylene oxide, or propylene oxide to alkali chitin or chitosan at room temperature and pressure or at 5° to 60"C at a rate of 1 to 5 kg/cjG. It can be obtained by reacting under pressure.

■Carboxymethyl chitin or chitosan [in the formula, n:]
■ R4 knee H or -COCH3 R, knee H, -CH, COOH, -CH, COONa,
-CHlGOOK or -CH,C00NH,.

R,: -I-I, -CH1C○OH, -CH,COO
Na, -CH,GOOK or -CH,C00NH.

represents. However, R6 and R, cannot both be -H, and in the individual D-glucosamine skeletons that are bonded, R4? R5=RG may be the same or different. ] This carboxymethyl chitin or chitosan.

Add monochloro vinegar to alkaline chitin or chitosan at room temperature.
It can be obtained by reacting under normal pressure.

■Phosphorylated chitin or chitosan However, R8 and R1 do not become -H at the same time.

or -NH4) and also with each linked D-glucosamine skeleton R7,R,,R,,R. may be the same or different, respectively.) This phosphorylated chitin or chitosan is produced by reacting chitin or chitosan dissolved or suspended in methanesulfonic acid with niline pentoxide under cooling.

This can be obtained by This method is described, for example, in Proceedings of the 48th Autumn Annual Meeting of the Chemical Society of Japan, p. 570 (Yonori et al.).

(2) Represents sulfated chitin or chitosan (in the formula, n:〉1-NH4)-NH4). Furthermore, in the individual D-glucosamine skeletons that are bonded, R2□, R1, 3. R□ may be the same or different. ] This sulfated chitin or chitosan can be obtained by reacting chitin or chitosan activated in pyridine with a so-pyridine complex [References: M,
L. Wolfrom et al.
nation of Chitosan, J.
Am, Soc,, 81.

1764-1766 (1959)].

■N-Glycidyltrimethylammonium chitosan (Cxx is CQ or Br) (xi is CQ or Br) This N-glycidyltrimethylammonium chitosan is produced by adding glycidyltrimethylammonium chloride to chitosan under high temperature and high pressure under a highly concentrated alkali catalyst. It can be obtained by

(Φ dihydropropyl chitin or chitosan [where n:
〉■ R1,: -H or -COCH.

represents. However, Rls and R□ do not become -H at the same time.] This dihydroxypropyl chitin or chitosan can be obtained by ring-opening and adding epichlorohydrin to alkali chitin or chitosan at a high temperature.

(2) N-2-hydroxypropylsulfonic acid chitosan [where n:>1 represents (M13 is Na, K or -NH4) (M04 is Na, K or -NH4). However, R2° and R2□ do not become -H at the same time. ] This N-2-hydroxypropylsulfonic acid chitosan can be obtained by adding glycidyl sulfonic acid to chitosan under an alkali catalyst at high temperature and pressure.

Note that as a solvent for dissolving water-soluble chitin and chitosan, an aqueous solvent such as water can be used.

Further, there is no limitation on the method of reduction treatment, but a method of applying a reducing agent, a catalytic hydrogenation method, etc. can be suitably employed.

In this case, examples of the reducing agent include metals such as lithium and sodium, metal hydrides such as sodium borohydride, sodium cyanoborohydride, lithium aluminum hydride, and diphenyltin hydride. It is not limited. The reaction solvent varies depending on the type of reducing agent, but for example, when sodium borohydride is used, water is sufficient. The concentration of chitin and chitosan in the solvent is preferably 0.01 to 50.
% by weight, more preferably 0.1 to 10% by weight. The amount of reducing agent depends on the type and is not constant, but chitin,
It is preferably 0.01 to 50% by weight based on chitosan,
More preferably, 0.1 to 20% by weight is used. The temperature of this reduction reaction.

Although the time varies depending on the type of reducing agent, the temperature is preferably in the range of 0 to 100°C, more preferably 10 to 80°C, and the time is preferably in the range of 1 to 24 hours, more preferably 2 to 8 hours. be. Note that, if necessary, an acid or alkali such as hydrochloric acid or alkali hydroxide can be added to adjust the pH in the reaction solution.

According to the present invention, after the reaction is completed, the reaction solution is desalted using an ion exchange membrane, ultrafiltration, and dialysis, and then dried to produce water-soluble chitin and chitosan with good quality stability. Can be collected.

〔Effect of the invention〕

As explained above, according to the treatment method of the present invention, quality stability of water-soluble chitin and chitosan can be improved. Water-soluble chitin is resistant to quality deterioration such as the formation of water, and can be effectively used in various fields such as pharmaceuticals, foods, and miscellaneous goods.

It is possible to obtain chitosan.

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples.

[Example 1] After adding 10% hydrochloric acid 10Ω to 2kg of chitosan.

The mixture was left at room temperature for 18 hours and hydrolyzed to reduce the molecular weight. Then p I-I with 50% sodium hydroxide
After making it slightly alkaline, add 1 portion of sodium borohydride.
00g was added and mixed for 3 hours at room temperature.

Afterwards, it is desalted using an ion exchange membrane and dried, resulting in a white color.

1.9 kg of odorless low molecular weight chitosan was obtained.

A 1% aqueous solution of this low-molecular-weight chitosan was placed in a constant temperature bath at 40°C for 3
When stored for several months, no coloration, off-odor, or precipitation occurred.

[Example 2] To 40 g of an aqueous solution containing 2 g of ethylene glycol chitin,
0.5 g of sodium borohydride while stirring at room temperature.
After adding, the temperature was raised to 80°C and stirred for 6 hours. next,
After the reaction solution was returned to room temperature, it was desalted by ultrafiltration and dialysis, and then freeze-dried to obtain 1.8 g of a product.

Ethylene glycol chitin obtained by the above treatment (treated product) and raw material ethylene glycol chitin (untreated product)
A 0.5% aqueous solution of each was stored in a constant temperature bath at 50°C,
Coloring, odor, degree of precipitation, pH, initial stage,
Measurements were taken after 2 weeks, 4 weeks, and 6 weeks. The results are shown in Table 1 below.

1 The degree of coloring was measured using a color difference meter (N
D-101D type) was used, and the degree of discoloration was determined by measuring a and b values using a UC8 system (isochromatic color system). In addition, the degree of generation of off-odor and precipitate was evaluated by sensory evaluation and visual observation. Here, the transparent colors a and b each represent the position of a point in spatial coordinates (three-dimensional orthogonal coordinate system).

As is clear from Table 1, ethylene glycol chitin treated with sodium borohydride showed little pH change even when stored at 50°C, and no off-odor or precipitation was observed, indicating the degree of coloration. The degree of discoloration was low, and no changes were observed in physical properties.

On the other hand, the pH of untreated ethylene glycol chitin tended to decrease, and a foul-smelling precipitate was generated over time.

Furthermore, the degree of discoloration, which indicates the degree of coloring, also increased significantly.

Applicant: Laion Co., Ltd. Agent: Patent Attorney Takashi Kojima

Claims (1)

[Claims] 1. A method for stabilizing water-soluble chitin or chitosan, which comprises subjecting water-soluble chitin or chitosan to reduction treatment in a homogeneous solution system.