Screening of chemical composition of black soybean hulls: a comparative study of different extraction techniques

Black soybean hulls have been reported to contain abundant anthocyanin pigments, which can be used as a colorant in food as well as non-food industries. In this study, anthocyanins were extracted from black soybean hulls using different extraction techniques such as aqueous extraction (solid to solvent ratio 1:20 g/mL, temperature of 40 °C for 65 min), microwave treatment (solid to solvent ratio 1:22 g/mL, microwave power of 240 W for 91s), ultrasound treatment (solid to solvent ratio of 1:26 g/mL, ultrasound power of 200 W for 50 min, and ethanol 90% v/v), and enzyme treatment (60% ethanol, solid to solvent ratio of 1:20 g/mL at 37 °C for 90 min). The results of this investigation showed that the enzyme-assisted extraction method showed the presence of the highest number of phytochemical compounds compared to other methods investigated in this study. Additionally, hull extracts displayed the presence of various important compounds that can be used in different industries, including as a pigment in the food industry which enhances the nutritional value, develops functional food, upgrades food quality, and is also beneficial in the pharmaceutical industry.