Effects of extraction process on phenolic content and antioxidant activity of soybean

Abstract

In this research, a set of experiments was carried out for identifying the optimum conditions of independent variables affecting phenolic content extraction efficiency and antioxidant activity of soybean seeds (Glycine max L.). They included the use of diff erent organic solvents (methanol, ethanol and acetone); concentrations of solvent (40, 50, 60, 70, 80, and 90 v/v, %); the ratio between soybean seeds and solvent (1:4, 1:6; 1:8 and 1:10) and the number of extraction times (2, 3 and 4 times); the extraction time (2, 3 and 4 hours) and the temperature (30, 40, 50 and 60°C). The extraction abilities of phenolics manifested in forms of total phenolic and total flavonoid contents (TPC and TFC) as well as the antioxidant activity by 1,1-diphenyl-2-picryl hydrazyl radical scavenging (DPPH) were used as assessment indicators. Generally, high extraction yield was obtained using aqueous acetone 70% as solvent; the most suitable ratio between soybean seeds and solvent was 1:6 for 3 times of extraction. The extraction yield could further be increased using a prolonged time of 3 hours at the temperature of 40°C.