Porous starches modified with double enzymes: Structure and adsorption properties.

To explore an effective enzyme combination instead of a common enzyme method, sequential α-amylase and glucoamylase, a method of sequential glycosyltransferase and branching enzyme was chosen to compare the macroscopic features, structure characteristics, porosity characteristics and adsorption quantity of potato, corn, wheat and sweet potato starches. The results indicated that after enzyme treatment, the relative crystallinity of potato, corn, wheat and sweet potato starches increased. Moreover, amylose levels decreased, while pore size and volume, and specific surface area increased after sequential glycosyltransferase and branching enzyme. In terms of pore size, sequential α-amylase and glucoamylase produced abundant mesopores (2-50 nm), whereas sequential glycosyltransferase and branching enzyme developed much more macropores (>50 nm). The adsorption quantities of the starch obtained with sequential glycosyltransferase and branching enzyme were about 2 folds higher than that of the starch obtained with sequential α-amylase and glucoamylase. Therefore, the sequential glycosyltransferase and branching enzyme may be an ideal method to create porous starch as a desirable green adsorbent for industries.