Mechanism analysis for the differences in multi-level structure, enzyme accessibility and pasting properties of starch granules caused by different hydrolysis pathways of maltogenic α-amylase

The effect of pores distribution on the multi-scale structure, enzyme accessibility, and pasting properties of the waxy maize starch granules with the same degree of hydrolysis were examined. Increased maltogenic α-amylase (MA) dosage obviously increased the shallow pores number and the roughness, whereas extended time increased the holes depth. Despite achieving the same hydrolysis degree and specific surface area, samples with numerous shallow holes exhibited a higher mass fractal dimension, a lower, peak viscosity, final viscosity and setback. Besides, increased dosage prompted a sustained decrease in the number of short chains with DP 10-17; whereas prolonging time encouraged the continuous catalyzation in the same chains. Enzymatic probe profiles showed MA was more accessible to the amorphous region on the periphery of starch granules, rather than the inside. This finding provides a more valuable understanding of the catalytic mechanism for MA in heterogeneous systems and an accurate guidance for the industrial production.