Total phenolic content and antioxidant activities of pomegranate juice and whey based novel beverage fermented by kefir grains.

Abstract

Mixture of pomegranate juice and whey was evaluated as a potential substrate for production of a novel beverage by kefir grains. The effects of two different variables, fermentation, temperature (19 and 25 °C) and kefir grain amount (5 %w/v and 8 %w/v), on total phenolic content (TPC) and antioxidant activities of beverage were examined during a fermentation time of 32 h. TPC and antioxidant activities including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power, inhibition effect upon linoleic acid autoxidation and inhibition effect upon ascorbate autoxidation increased significantly (p < 0.05) during fermentation, but metal chelating effect showed no significant difference. The highest increases were observed when the temperature of 25 °C and kefir grain amount of 8 %w/v were applied. Results proved antioxidant activities of beverages were desirable and fermentation by kefir grains has the ability to enhance these antioxidant activities, as compared with unfermented beverage. Also pomegranate juice and whey were suitable media for producing a novel dairy-juice beverage.