Extraction and Antioxidant Activity Evaluation of Polyphenols of Brown Rice Tea from Japonica Rice and Indica Rice

The objective of this study was to explore the extraction process and antioxidant activity of polyphenols from Japonica and Indica brown rice. After baking, Japonica and Indica brown rice samples were soaked in water to obtain brown rice tea respectively. We determined the polyphenol content and the antioxidant activity of the brown rice tea, as well as measured the contents of nutrients (including protein, amino acid, and crude cellulose) of the baked brown rice. The total AA content of Indica brown rice (7.30%) was higher than that of Japonica brown rice (6.30%). The results showed that the optimum extraction conditions for Japonica and Indica rice polyphenols were as follows: baking temperature of 180°C and 190°C, baking time of 15 min and 20 min, and soaking time of 30 min and 30 min, respectively. The DPPH clearance rate of the five samples was shown as follows: Burdock tea> Pu’er tea> Tieguanyin tea> Japonica brown rice> Indica brown rice tea. The DPPH clearance rate of the polyphenols in rice tea obtained from Japonica and Indica brown rice was 1.04% and 1.99%.