Effect of heat treatment on starch granule structure and nutrient content of germinated purple rice

Abstract

This study aims to determine the effect of heat treatments on milling quality and some nutrients of germinated glutinous purple rice; we performed an experiment in a 3x2 factorial design with three replications. The first factors were three heating methods, namely; baking (80, 100 °C) and steaming (100 °C), and the second factors were two heating periods (15 and 30 min). Dried germinated rice was used as control. Heating method and duration as well as their interactions, significantly affected the milling quality and anthocyanin extraction (P < 0.05). Steaming at 100 °C for 30 min significantly increased head rice (73.4%), while baking at 100 °C for 30 min resulted in the highest amount of broken rice (42.3%). These method also maintained the GABA (γ-aminobutyric acid) content of the rice, while anthocyanin extraction was decreased from 52.1 to 29.9 mg•g-1. Heating at 80 °C for 30 min, 100 °C for 10 and 20 min and 125 °C resulted in a higher free radical scavenging ability when compared to unheated rice.