Evaluation of enzyme and microwave-assisted conditions on extraction of anthocyanins and total phenolics from black soybean (Glycine max L.) seed coat.

The present study compares three methods viz. microwave-assisted extraction (MAE), enzyme-assisted extraction (EAE) and conventional solvent extraction (CSE) for extraction of polyphenolic compounds from Black Soybean Seed coat (BSSC). Box-Behnken design using response surface methodology (RSM) was employed to investigate and optimize the MAE and EAE for maximum bioactive content, antioxidant activity, colour density and minimum degradation parameters from BSSC. Optimized MAE conditions for BSSC were: microwave power of 569.46 W, extraction time of 262.54 s, solvent to solid ratio of 40:1 and ethanol concentration (59.99). The predicted anthocyanin content was 5021.47 mg/l, close to experimental optimized value of 5094.9 mg/l with minimum values of degradation parameters viz., Polymeric Colour (PC) (0.131 ± 0.01), Browning Index (BI) (0.202 ± 0.02) and Degradation Index (DI) (0.140 ± 0.02). Overall results clearly indicate that MAE is the best suited method for extraction in comparison to EAE and CSE. The phenolic rich extract can be used as an effective functional ingredient in foods.