Relationships between amylopectin molecular structures and functional properties of different-sized fractions of normal and high-amylose maize starches

The amylopectin molecular structures and functional properties of different-sized fractions of normal and high-amylose maize starches were investigated and compared in this study. The different-sized fractions of normal starch showed similar amylopectin molecular structures and functional properties. The small-sized fraction of high-amylose starch had significantly higher amylopectin long branch-chain and average branch-chain length than its counterpart medium- and large-sized fractions. The swelling power, gelatinization enthalpy, and hydrolysis and digestion degrees of high-amylose starch significantly decreased with decrease of granule size, and were significantly positively correlated with amylopectin short branch-chain and negatively correlated with amylopectin long branch-chain and average branch-chain length. The gelatinization peak temperature and resistant starch content increased with decrease of granule size, and were significantly positively correlated with amylopectin long branch-chain and average branch-chain length and negatively correlated with amylopectin short branch-chain. The hierarchical cluster analysis indicated that the large-sized fraction of high-amylose starch was significantly different from the medium- and small-sized fractions of high-amylose starch but more relative with normal starch. The above results could provide important information for the applications of different-sized fractions of high-amylose maize starch. (C) 2015 Elsevier Ltd. All rights reserved.