The Bio-enzymatic Degradation Of Chitosan And Its Application

In this paper, chitosan was degradated by three kinds of enzymes-cellulase, pectinase, B -glucosidase and tannase, The degradation mechanism of enzymes was discussed. Finally, the eliminating OH and lard antioxidation of chitooligodaccharide were studied.The main contents of experiment were as follows:Determine the deacetylation degree(D.D.) of chitosan and chitin used in the experiments, the average viscosity molecular weight of chitosan and the molecular weight of chitooligodaccharide.In the condition that the dose of chitosan and the concentration of cellulase were changeless, the influence of the D.D., dose of cellulase, temperature and pH on the degradation reaction was studied. The degradation mechanism of cellulase was discussed. The experiment results were: the best condition of the degradation of chitosan by cellulase is: the D.D. is 97.74%, the dose of cellulase is 18.3ml, the temperature is 60C, the pH is 5.1. The influence of D.D. on the degradation is more than the other factors. The part acting on chitosan is possibly endo-cellulase, which cut off B -1,4-indican bond of chitosan . By the cellulase' catalysis , the chain of chitosan is made short, the resistance of molecules is reduced, the viscosity is dropped. The seven kinds of chitooligodaccharides are gained, whose molecular weight is about 1500.In the condition that the dose of chitosan and the concentration of pectinase were changeless, the influence of the D.D., dose of pectinase, temperature and pH on the degradation reaction was studied. The experiment results were: the best condition of the degradation of chitosan by cellulase is: the D.D. is 77.2%, the dose of cellulase is 0.2ml, the temperature is 42C, the pH is 3.8. The influence of D.D. on the degradation is more than the other factors. The degradation mechanism of pectinase was similar with that of cellulase. The six kinds of chitooligodaccharides are gained, whose molecular weight is about 947.In the condition that the dose of chitosan and the concentration of B -glucosidase were changeless, the influence of the D.D., dose of B-glucosidase, temperature and pH on the degradation reaction was studied. The experiment results were: the best condition of the degradation of chitosan by B -glucosidase is: the D.D. is 80.5%, the dose of B -glucosidase is15ml, the temperature is 77.5C, the pH is 5.7. The influence of D.D. on the degradation is more than the other factors. The eight kinds of chitooligodaccharides are gained, whose molecular weight is about 1123.In the condition that the dose of chitosan and the concentration of tannase were changeless, the influence of the D.D., dose of tannase, temperature and pH on the degradation reaction was studied. The experiment results were: the best condition of the degradation of chitosan by tannase is: the D.D. is 97.74%, the dose of tannase is 28ml, the temperature is 30 C, the pH is 4.8. The influence of D.D. on the degradation is more than the other factors. The five kinds of chitooligodaccharides are gained, whose molecular weight is about 1536.Chitooligodaccharides are capable of eliminating OH, the experiment results were: The shicker the concentration of Chitooligodaccharides degradated by cellulase, the better the capacity of eliminating OH is. In the Chitooligodaccharides degradated by different enzymes with the same concentration, the capacity of eliminating OH of Chitooligodaccharides degradated by cellulase is best, that of B -glucosidase is least. The antioxidation of chitooligodaccharides are different, the sole chitooligodaccharide has not antioxidation, the mixture of chitooligodaccharide and Vc has the similar antioxidation with BHT.