Effect of annealing on the hydrolysis of sago starch granules

Sage starch annealed at varying temperatures, time intervals and pH was used to study granule hydrolysis by a glucoamylase (AMG) and a-amylase (Termamyl) mixture. Differential scanning calorimetry (DSC) indicated that there was a relationship between the extent of annealing and starch granule hydrolysis. Enthalpy of gelatinisation of annealed starch granules remained unchanged, suggesting that no gelatinisation had occurred. The degree of hydrolysis increased and the granule degradation pattern altered-from surface erosion to preferential digging of the internal regions of the granule. Sections of the hydrolysed granule residues revealed that enzymes attacked from one point on sufficiently annealed granules, and that after extensive hydrolysis, only an empty shell remained. (C) 1997 Elsevier Science Ltd.