Study on Preparation of Low Molecular Weight Chitosan by Papain and Acid

The preparation of low molecular weight chitosan are investigated. The optimal conditions for degradation of chitosan are determined as follows :reaction temperature 45 ℃ and reaction time 2 h by papain; reaction temperature 30 ℃ and reaction time 4 h by hydrochloric acid; reaction temperature 90 ℃ and reaction time 8 h by acetic acid. Then, on the basis of these, the preparation method is set and the reaction time is optimized to 7 h. The experimental results show that, under the same conditions, the viscosity of the final product degraded by both papain and acid is lower than that of final product degraded by papain or acid only. The molecular weight of degraded product decreases from 33 523.14 to 3 134.11.