Physicochemical Properties of Starches in Proso (Non-Waxy and Waxy) and Foxtail Millets (Non-Waxy and Waxy)

Abstract

Proso and foxtail millets are widely cultivated due to their excellent resistance to biotic and abiotic stresses and high nutritional value. Starch is the most important component of millet kernels. Starches with different amylose contents have different physicochemical properties. In this study, starches in proso (non-waxy and waxy) and foxtail millets (non-waxy and waxy) were isolated and investigated. All the starch granules had regular polygonal round shapes and exhibited typical “Maltese crosses”. These four starches all showed bimodal size distribution. The waxy proso and foxtail millets had higher weight-average molar mass and branching degree and lower average chain length of amylopectin. These four starches all presented A-type crystallinity; however, the relative crystallinity of waxy proso and foxtail millets was higher. The two waxy millets had higher onset temperature, peak temperature, conclusion temperature, and gelatinization enthalpy. However, the two non-waxy millets had higher setback viscosity, peak time, and pasting temperature. The significantly different physicochemical properties of waxy and non-waxy millet starches resulted in their different functional properties.