Effect of Induced Electric Field on Structural Properties and in Vitro Digestibility of Corn Starch Hydrolyzed by Pullulanase

Abstract

The effect of induced electric field on the structural properties and in vitro digestibility of corn starch (CS) hydrolyzed by pullulanase was studied. The results showed that after IEF-assisted enzymatic hydrolysis, a large number of holes appeared in the modified corn starch granules, and the polarization cross became blurred. The ratio of absorbance 1 047/1 022 cm−1 in the crystallization zone increased, whereas the ratio of absorbance 1 022/995 cm-1 decreased. The relative crystallinity increased with the increase in induction voltage. The relative content of amylose initially increased and then decreased. At an induction voltage of 125 V, the relative content of amylose was 98.61%. The solubility and swelling power initially decreased and subsequently increased, while the hardness and cohesiveness showed the opposite trend with increasing induction voltage. The viscosity of both raw and treated starch decreased rapidly with the increase in shear rate. Both storage and loss moduli were related to the amylose content. The relative content of resistant starch was 62.46% at an induction field of 125 V. Both in vitro digestibility and glycemic index decreased first and then increased. This study provides a theoretical reference for the application of induced electric field in the production and development of modified starch.

Keywords

• corn starch; pullulanase; induced electric field; structural performance: in vitro digestibility