Functional analysis of the bioactive compound contents and antioxidant activity of extract red rice beverage

Abstract

Rice is an important commodity which is can be an effective vehicle in overcoming health problems. Several types of Indonesian rice varieties are pigmented rice (red, black, and purple). The content of phenolic, flavonoids and antioxidant activity in red rice is known to be more than in rice is not pigmented. The extract from red rice has the potential to be a beverage that is rich in antioxidants and other nutrients. This study was carried out the health potential of red rice such as bioactive compounds and antioxidant activity at post-processing. Four types of red rice commercially were used in this study. The initial test was carried out by extracting the four red rice using methanol (without processing condition), this is used for comparison. The processing condition of red rice beverages (extraction temperature of 90 °C, water: rice powder ratio of 20 ml/g, 25 ml/g, 30 ml/g, extraction time of 15 and 25 minutes). The samples were tested for total phenolic content, flavonoid, and antioxidant activity. The highest total phenolic content, flavonoid, and antioxidant in the samples without processing condition was 12.9 mg GAE/g, 5.7 mg QE/g, and 81.84%. Furthermore, the highest total phenolic content, flavonoid, and antioxidant activity of red rice extract with processing condition was 4.26 mg GAE/g (water: rice powder ratio of 20 ml/g, for 15 minutes), 14.13 mg QE/g (water: rice powder ratio of 25 ml/g, for 15 minutes) and 69.02% (water ratio of 25 ml/g, for 15 minutes), respectively. The processing of red rice extract beverages showed a decrease in antioxidant activity of 10.52-30.94% when compared to the samples without processing condition, and the decrease was less than 50%. So, it can be potential as a beverage that is rich in antioxidants. The extraction time for 15 minutes given the best result when compared to the extraction time for 25 minutes, it was indicated that could provide the best processing condition for making red rice beverages that are rich in the bioactive compound and antioxidant.