Effects of soaking and gaseous treatments on total phenolic, anthocyanin concentration and antioxidant capacity of germinated red, white and black rices

Abstract

The aim of this study is to determine the total phenolic content (TPC), flavonoid content (TFC), DPPH radical scavenging, anthocyanin concentration, chemical compostions and enzyme activity of three types of germinated rices including black, red and white rice by applying soaking treatment. All types of rices were carried out at different conditions of soaking time in water such as 0.5, 1, 2, 3, 4, 5 hours, then continued to incubate (not allowed to air exchange) in 23.5, 23, 22, 21, 20, 19 hours, respectively. After germination, all types of germinated rices were investigated and analyzed for their TPC, TFC, DPPH radical scavenging, anthocyanin concentration, chemical compositions and enzyme activities (diastatic, alpha-amylase and protease activity). The result of study showed that these parameters were significant differences among non-germinated and germinated rices in experimental conditions. Bioactive compounds, including TPC, TFC and DPPH scavenging ability decreased approximately 50% after soaking and gaseous treatment. Especially, in case of anthocyanin, while the concentration of black germinated rice decreased seriously (from 34 to 3.57 mg/L), the red ones increased slightly (0.21 to 1.46 mg/L). The enzyme activities including diastatic, alpha-amylase and protease were recorded dramatical increase after treatment. In addition, the chemical compositions - protein, ash, lipid slightly decreased, whereas the percentage of carbohydrate nearly unchanged. Key words: germinated rice, phenolic content (TPC), flavonoid content (TC), DPPH radical scavenging, chemical compostion, anthocyanin, enzyme activity.