| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a low-molecular weight chitosan by which the low-molecular weight chitosan can inexpensively and stably be produced in large amounts and utilized for various fields and to provide a high-purity low-molecular weight chitosan suitable for utilization in the cutting-edge realm such as pharmaceuticals. SOLUTION: This method for producing the low-molecular weight chitosan comprises carrying out acid hydrolysis reaction of chitosan by using hydrochloric acid as a catalyst. The low-molecular weight chitosan having 10,000 to 20,000 weight-average molecular weight is preferably produced by the method. In the production method, acid hydrolysis reaction is carried out, preferably in >=3% hydrochloric acid concentration and a weight of >=5 times based on chitosan at >=40 deg.C decomposition temperature of chitosan, more preferably in 5-8% hydrochloric acid concentration and a weight of 8-16 times based on chitosan at 70-90 deg.C decomposition temperature. In the production method, membrane-separation is carried out after acid hydrolysis reaction. The low-molecular weight chitosan is preferably composed of the low-molecular weight chitosan having 10,000 to 20,000 weight-average molecular weight and a high-purity low-molecular weight chitosan having nearly 10,000 weight average molecular weight. A composition comprising the low molecular weight chitosan, preferably food, cosmetic or medicine is also provided. |
