Effects of superfine grinding on physicochemical properties and morphological structure of coix seed powders

This study investigated the effects of superfine grinding on the physicochemical properties and morphological structure of coix seed powders. In this study, five coix seed powders with different particle sizes were prepared through superfine grinding, and the properties of the coix seed powders obtained from superfine grinding were compared with those acquired from conventional grinding. When the particle size of the coix seed powder decreased, its specific surface area and brightness increased, and agglomeration became obvious. When the particle size decreased to 19.08 μm, coix seed powder distribution became gradually uniform. After superfine grinding, gelatinisation temperature decreased from 65.04 °C to 62.78 °C, and the heat absorption enthalpy decreased from 2.11 to 0.33 J/g. The final viscosity of the conventional grinding (W-60) sample was the highest (1271.33 CP), and the recovery value of the superfine grinding15min (C-15) sample was the lowest (176.00 CP). Superfine grinding did not lead to changes in the crystal structure and functional groups of the coix seed powder; however, crystallinity gradually decreased with a particle size decrease (P < 0.05). This study showed that superfine grinding can considerably lower the particle size of the coix seed powder and improve its pasting and thermal properties.