Beta Vulgaris L. Extract: pH Effect on Total Phenolic Content and Antioxidant Properties

Abstract

Red beet (Beta vulgaris L.) is a rich source of phenolic content including colour pigments and have also high antioxidant capacities. The amounts of their phenolic substances and antioxidant activities change depending on the extraction conditions (pH, time, solvent, etc.). In this work, the coloured water extracts were obtained from red beet at different pH values (pH 4-10) for both an hour and 24 hours. The extracts were evaluated regarding antioxidant activities and total phenolic contents (TPC). The results showed that the total phenolic content of red beet extract in all extraction conditions ranged from 0.55±0.02 to 2.30±0.19 mg GAE/g FW. The highest total phenolic contents (2.30±0.19 mg GAE/g FW) were obtained from red beet at 24 h and pH=4. On the other hand, while the IC50 values for DPPH activity of red beet extracts at all pH values and times are between 0.84±0.04 and 5.44±0.75 mg/mL, the IC50 values for ABTS activity are between 1.46±0.42 and 3.65± 0.28 mg/mL. The extract obtained from red beet at 24 h and pH=4 exhibited the strongest DPPH activity with the IC50 values of 0.84±0.04 mg/mL, it showed the best ABTS activity with the IC50 values of 1.46±0.42 mg/mL at 24 h and pH=4.