Abstract:The materials prepared by high amylose starch have good properties and applications. But the melt viscosity of high amylose starch is poor and extrusion processing energy consumption is high. In this paper, the tolerance of enzyme in extrusion environment and the effects of the addition and the extrusion time on the mechanical energy and the mechanical properties of materials were investigated used the enzyme-extrusion composite technology. The results showed that the thermostable α-amylase could maintain enzyme activity in the extrusion environment under high temperature, high pressure, and high shearing force. Besides, they could improve the phase transition of high amylose granules, promote the extrusion processing, and then reduce the extrusion time and decrease the mechanical energy. Specifically, the specific mechanical energy of G50 high amylose starch could decrease by 21 %, and the tensile strength and elongation of materials were also reduced by 33 % and 83%, respectively when the addition of enzyme was only 0.25 % of starch (dry weight).. . On the other hand, the thermostable α-amylase had no significant effect on the extrusion of G80 high amylose starch. These results illustrated that the synergistic effects of enzyme-extrusion composite technology could conserve the extrusion processing energy of high amylose starch and reduce extrusion time. Moreover, enzymatic hydrolysis could increase the active site and reaction efficiency of starch, which was beneficial to the starch reaction extrusion.
