Effects of fractionation and heat-moisture treatment on structural changes and digestibility of debranched waxy maize starch

The effects of fractionation (chain length) and recrystallization (starch solids concentration) combined with heat-moisture treatment (HMT) on the reorganization and resistant starch (RS) formation of debranched waxy maize starch (DWMS) were investigated in this study. Waxy maize starch (WMS) was debranched at 5% and 10% starch concentrations and 24 h, and the parent DWMS was fractionated in different ethanol solutions (ethanol: water 1:1.5 and 1:3.0), and further subjected to HMT to enhance RS content. The fractionated products DWMS1.5 and DWMS3.0 (RS content: 48.0%–62.4%) were more resistant to enzyme digestion than the parent DWMS products (35.1%–39.4%). HMT broadened the endotherms and increased crystallinities and enthalpies of DWMS products. Fractionation combined with HMT led to A-type structure formation of DWMS, with a higher peak melting temperature (115.31 °C) and a higher RS content (86.7%). Moreover, this knowledge can be used for optimization of RS-containing products with different degrees of resistance to enzyme digestion based on recrystallization in combination with HMT.