OPTIMIZATION OF SOAKING CONDITIONS FOR IMPROVING THE GERMINATION RATE, TOTAL POLYPHENOL CONTENT, ANTIOXIDANT ACTIVITY OF NEWLY RESTORING VD20 RICE

Abstract

This study is aimed to optimize soaking conditions, including soaking temperature, pH of soaking solution, and soaking time for maximizing the rice germination rate and biological properties [total polyphenol content (TPC) and Ferric Reducing Antioxidant Power (FRAP) as know as antioxidant activity] of VD20 germinated rice. The Box-Behnken design by using response surface methodology was used to build experimental design. The results showed that the significant impact of each treatment on the sprouting rate as well as content of TPC and value of FRAP in VD20 rice. The desirability function approach was applied to find the optimal soaking conditions leading to germination with the highest phenolic content, value of FRAP and germination rate. The optimum conditions were determined as soaking time of 6.36 hours, soaking temperature of 26oC and pH of 4.65. In these optimized conditions, the expected total phenolic content, antioxidant activity and germination rate of VD20 rice were 33.42 mgGAE/100 g, 36.9 μM TE/g and 97.55%, respectively, which was further values confirmed by experimental test. This work showed that soaking process has a significant impact on polyphenols, which could enhance the nutrition of the product. The obtained product with high antioxidant activity could be further utilized in nutraceutical foods.