Method of using alpha-glucosidase for preparing isomaltooligosaccharide

The invention relates to a method of using alpha-glucosidase for preparing isomaltooligosaccharide. The method includes alpha-glucosidase immobilization, continuous reaction and isomaltooligosaccharide preparation. The alpha-glucosidase is immobilized through alginate, carrageenan and chitosan to implement continuous reaction, converting rate of raw material is 75%, and production cost is reduced by 1/3. By the aid of the method, isomaltooligosaccharide 50 or total isomaltooligosaccharide content of the isomaltooligosaccharide 50 is 55%, and the total content of isomalt, panose and isomaltotriose is 35%; isomaltooligosaccharide 90 or total isomaltooligosaccharide content of the isomaltooligosaccharide 90 is 95%, and the the total content of isomalt, panose and isomaltotriose is 70%.