Degradation kinetics of anthocyanins from purple rice bran and effect of hydrocolloids on its stability

Abstract

AbstractThe degradation kinetics of total anthocyanin, cyanidin‐3‐glucoside (C3G), and peonidin‐3‐glucoside (P3G) from purple rice bran were investigated in various pH and temperature conditions. The effect of hydrocolloids on the stability of anthocyanins was also determined. The degradation kinetics was studied in a pH range of 2–8 and temperatures ranging from 60 to 90°C. At pH 2, the total anthocyanin (2.21 × 10−4 min−1), C3G (1.44 × 10−4 min−1), and P3G (1.38 × 10−4 min−1) showed the lowest degradation rate. During thermal degradation, the lowest rate of degradation for total anthocyanin (3.46 × 10−4 min−1), C3G (1.75 × 10−4 min−1), and P3G (1.99 × 10−4 min−1) were observed at 60°C. The highest degradation rate of total anthocyanin, C3G, and P3G, was obtained at pH 6 and 90°C. The effect of carboxymethyl cellulose, xanthan gum, modified starch, and gum arabic on the stability of anthocyanin, C3G, and P3G was significant (p ≤ .05). The modified starch system showed the highest stability of anthocyanins and antioxidant activity in the aqueous medium. The degradation kinetics of anthocyanins in modified starch medium revealed a lower degradation rate than without a hydrocolloid sample.Practical applicationsAnthocyanins are easily affected by food processing factors, such as pH and thermal treatment. Thereby, the temperature range used in the present study is commonly used during food processing, namely, pasteurization, blanching, and drying. Similarly, the applied pH range is also widely available in the food product. Therefore, the kinetic analysis of this work can be used to evaluate the loss and degradation behavior of anthocyanin during industrial processes. In the present study, the stability of anthocyanins in the various hydrocolloids medium was also investigated under different conditions. Thus, this study has the potential application in the food processing industries to develop a stable anthocyanin‐based product.