This study investigated the effects of acid degradation of amylopectin on the structure, pasting, and rheological properties of waxy maize starch. It is found that: 1) the amount of amylopectin short-chains with degree of polymerization (DP) ~ 15-50 increased while that of amylopectin long-chains with DP ~ 50-200 decreased by acid hydrolysis; 2) acid hydrolysis produced smaller amylopectin molecules with a narrower size distribution; 3) acid hydrolysis had a minor effect on the crystalline and granular structures of native starch; 4) the pasting viscosity of acid hydrolyzed starch during heating and the consistency coefficient, K, of starch gels increased, whereas the flow behavior index, n, decreased. Correlation analysis was used to clarify the molecular causes for the variations of pasting and rheological properties of acid hydrolyzed starch.
Keywords: Acid hydrolysis; Amylopectin; Molecular structure.
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