Preparation of Multienzyme Complex and Condition Optimization for Degradation of Macromolecules in Upper Tobacco Leaves

To decrease the contents of starch and proteins in upper tobacco leaves, four types of enzyme (amylase IV, protease I, pectase I and cellulase Ⅱ) were selected to prepare a multienzyme complex (MEC). The effects of multienzyme complex content, buffer pH, moisture content and enzymatic hydrolysis time on degradation rate of starch and proteins were studied by single factor experiment and Box-Benhnken experimental design of the response surface methodology. The results of ANOVA and response surface analysis showed that, degradation of both starch and proteins was significantly influenced by the 4 factors in the order of:buffer pH > enzymatic hydrolysis time > moisture content > multienzyme complex content. The optimum enzymatic conditions at 40℃ were obtained as follows:multienzyme complex content of 1.1 unit (amylase IV 33 U/g, protease I 550 U/g, pectase I 220 U/g and cellulase Ⅱ 220 U/g), buffer pH 7.7, moisture content of 54%, and enzymatic hydrolysis time of 5.5 h. Under this condition, the degradation rate of starch and proteins were determined to be 19.54% and 20.03%. The optimized multienzyme complex and enzymolysis conditions could be promisingly applied to the threshing and redrying process of tobacco leaves.