Effect of the electric field treatment on the pullulanase-catalyzed hydrolysis of waxy rice starch

Abstract

Objective: This study aimed to classify the mechanism of pullulanase-catalyzed hydrolysis of waxy rice starch under electric field treatment, by monitoring the changes in hydrolysis efficiency, pullulanase activity, and the structure and properties of waxy rice starch. Methods: The hydrolysis efficiency was determined, and the structure and thermal properties of hydrolysates were characterized, by using scanning electron microscope, X-ray diffractometer, differential scanning calorimeterand rapid viscosity analyzer. Results: Under the control of the following conditions, electric field with intensities ≤2.5 V/cm could increase pullulanase activity, accelerate the hydrolysis, induce the pores and cracks on the granule surface, increase the relative crystallinity, increase the gelatinization temperature and reduce the pasting viscosity of waxy rice starch. However, electric field with intensities ≥5 V/cm could cause the partial inactivation of pullulanase and reduce the hydrolysis efficiency, and consequently caused less change of the relative crystallinity and pasting viscosity. Conclusion: The strengthening effect of the electric field treatment on pullulanase hydrolysis of waxy rice starch mainly affected pullulanase activity, but has no significant effect on the structure of starch.

Keywords

• electric field
• pullulanase
• waxy rice starch
• hydrolysis