Effects of Germination Time and Temperature on Total Phenolic Content and Gamma-Aminobutyric Acid of Some Thai Rice Varieties

Abstract

Rice contains bran layers, endosperm and husk, where a variety of nutritional and biofunctional components, such as dietary fibers, gamma-oryzanol, vitamins, and minerals, exist. Germination is one of the techniques used to improve the texture and nutritional qualities of the rice. In this study, we investigated the effect of changes in different of germination time (24, 48 and 72 h) and temperature (30, 35 and 45oC) on the total phenolic content and gamma-aminobutyric acid (GABA) of RD-6 and Hombaitoei rice, compared with un-germinated samples. Overall, the total phenolic content, and GABA of the RD-6 and Hombaitoei rice showed an increasing trend as germinated time and temperature increased. Germination at 45oC for 72 h provided the highest total phenolic content of RD-6 and Hombaitoei rice for the germination treatments tested (p<0.05). Nevertheless, the amount of GABA of RD-6 and Hombaitoei rice was found to be the highest content at 30oC for 72 h of germination (p<0.05).