Partial hydrolysis of gelatinized barley and waxy barley starches by alpha-amylase

The hydrolysis of gelatinized commercial barley starch by Bacillus licheniformis alpha-amylase began by rapid depolymerization of amylopectin in two stages. The formation of low molecular weight hydrolysis products, as indicated by an increase in reducing power, was only observed when all the original high molecular weight amylopectin had degraded further. The hydrolysis of waxy barley starch followed a similar pattern. Hydrolysis had a big influence on the microstructure of the starch dispersion: first the degradation of the amylopectin rich granule residues (‘ghosts’) was observed, and later amylose aggregates were formed.