Effect of Moderate Electric Field on α-Amylase-Catalyzed Hydrolysis of Corn Starch

This study aimed to enhance α-amylase-catalyzed hydrolysis of corn starch via moderate electric field (MEF). The effect of MEF intensity, frequency, buffer concentration, and enzyme-solution ratio on enzymatic hydrolysis efficiency was investigated by using reducing sugar content as index. The structural and thermal properties of hydrolyzed starch were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). Results suggested that the hydrolysis efficiency was highly dependent on the electric field intensity, buffer concentration, and enzyme-solution ratio, but showed no significant change with increasing frequency. At MEF intensities lower than 5 V/cm, starch experienced a mild hydrolysis, the hydrolysates remained the granular and crystal structure as native starch, and the thermal stability slightly decreased. As MEF intensity increased, extensive hydrolysis happened, starch granules was broken into pieces, the crystallization peak gradually disappeared, the relative crystallinity decreased, the gelatinization temperature initially increased but then increased, and the thermal stability significantly decreased.