JPH0931105A - Production of low-molecular chitosan and chitooligosaccharide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce low-molecular chitosan and a chitooligosaccharide at efficiency better than that in a conventional method. SOLUTION: High-molecular chitosan is converted into low-molecular one and a chitooligosaccharide by irradiating a solution of chitosan with ultrasonic waves.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for efficiently producing low molecular weight chitosan and chitooligosaccharide.

[0002]

2. Description of the Related Art Oligosaccharides and low molecular weight chitosans can be used in a wide range of applications as food additives, pharmaceuticals, biochemical materials, etc. Conventionally, these are obtained by directly hydrolyzing chitosan with concentrated hydrochloric acid or the like. Was manufactured by.

However, when hydrolyzing chitosan with concentrated hydrochloric acid, a large amount of acid is required, and since the reaction is a heterogeneous system, decomposition easily proceeds from the end of the chitosan chain,
Since most of chitosan is decomposed to D-glucosamine monosaccharide, a large amount of glucosamine is produced.
Therefore, it was difficult to efficiently produce oligosaccharides and low molecular weight chitosan having a relatively high degree of polymerization. In addition, the post-treatment such as decolorization and desalting of the hydrolyzate of chitosan and purification are very inefficient, complicated and uneconomical.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention
It is intended to provide a method capable of producing low-molecular-weight chitosan and chitooligosaccharide more efficiently than ever before.

[0005]

In order to solve the above-mentioned problems, the present invention employs the following technical means.

In the method for producing low molecular weight chitosan and chitooligosaccharide of the present invention, the chitosan solution is irradiated with ultrasonic waves to lower the molecular weight of the high molecular weight chitosan and to generate the chitooligosaccharide.

The decomposition of a polymer by ultrasonic irradiation has a characteristic that it has an ultimate degree of polymerization and is not decomposed below that. Therefore, almost no D-glucosamine monosaccharide is produced, and an oligosaccharide having a relatively high degree of polymerization can be produced as compared with the conventional method.

Also, a large amount of acid or alkali is unnecessary,
It is also very effective in that post-processing becomes simple.

[0009]

The present invention is configured as described above and has the following effects.

Since almost no D-glucosamine monosaccharide is produced, it is possible to provide a method for producing low-molecular-weight chitosan and chitooligosaccharide more efficiently than before.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to embodiments.

In the method for producing low molecular weight chitosan and chitooligosaccharide of this embodiment, chitosan is mechanically sheared in a solution by ultrasonic irradiation.

First, 750 ml of purified chitosan was added to
It was dispersed in 150 ml of a 0.24% hydrochloric acid aqueous solution. Then, while the chitosan solution was stirred at 60 ° C., the irradiation surface of the horn was brought into direct contact with the ultrasonic wave of 28 KHz · 45 W for about 30 hours.

FIG. 1 is a graph showing the results of measuring the viscosity of the chitosan solution over time. After about 24 hours, the solution viscosity became almost constant, but this graph can be used as an index showing the state of low molecular weight. That is, about 24
Time is believed to be the limit for depolymerization of chitosan under the conditions of this embodiment.

The results of irradiating ultrasonic waves for about 24 hours while stirring the chitosan solution at 45 ° C. and 30 ° C. are also shown in FIG.

After the irradiation of ultrasonic waves was completed, the chitosan solution was neutralized to remove insoluble chitosan, and the solution was further concentrated and purified.

As a result, 113 mg of low molecular weight chitosan or chitooligosaccharide having a degree of polymerization of 3 to 12 was obtained. The yield was about 15%.

That is, according to the method of this embodiment, D
-Since almost no glucosamine monosaccharide is produced,
There is an advantage that low-molecular-weight chitosan and chitooligosaccharide can be produced more efficiently than before.

[Brief description of drawings]

FIG. 1 is a graph showing the results of measuring the viscosity of a chitosan solution over time.

Claims (1)

[Claims] 1. A method for producing a low molecular weight chitosan and a chitooligosaccharide, which comprises irradiating a solution of chitosan with ultrasonic waves to lower the molecular weight of chitosan which is a polymer and to generate a chitooligosaccharide. .