Effects of germination and roasting on physicochemical and sensory characteristics of brown rice for tea infusion

Abstract

Germinated brown rice was roasted for the preparation of tea. The germination induced substantial increases in reducing sugars (from 3224.06 to 5028.80 mg/100 g), free amino acids (from 62.51 to 165.07 mg/100 g), volatile compounds, and phenolics (10.06 to 14.27 mg GAE/100 g). Roasting decreased the residual contents of free amino acids and reducing sugars, but produced the volatiles and phenolics. Browning index was slightly decreased by the germination (from 22.69 to 20.13), but significantly increased by the subsequent roasting. The germinated BR (GBR) was more susceptible to roasting than native BR. Acrylamide content in the roasted GBR was significantly lower than that in the roasted BR, because of the lower asparagine content in GBR. Sensory evaluation revealed that a mild roasting for 5 min at 230 °C after germination for 2 days was appropriate to produce a brown rice tea.