Insights into maize starch degradation by sulfuric acid from molecular structure changes.

In this study, the molecular structure of hydrolyzed maize starch by sulfuric acid is analyzed by characterizing the chain-length distribution (CLD) and molecular size. It is found that molecular size is dramatically reduced by acid hydrolysis for only 1 h while amylose content is gradually decreased from 28.3 % to 4.6 % with hydrolysis time prolonging. By quantifying the subtraction of CLDs between hydrolyzed sample and native starch, we find: 1) the long chains with degree of polymerization (DP)∼500-30000 of native starch are degraded by acid hydrolysis for only 1 h; 2) with hydrolysis time extending, the degradation of short-amylose chains and even short amylopectin chains are initialized; 3) molecular size of hydrolyzed starch shows a strong correlation with the parameters derived from the subtraction analysis. This study could help to further understand molecular features from the individual chain assembling to a fully branched molecule.