Optimization of technology for ultrasonic-assisted extraction of pigments from black soybean hulls

Ultrasonic-assisted extraction of pigments from black soybean hulls was investigated. Based on the single factor experiments, the effects of different ultrasonic power, pH values and the ratios of solution to solid on the extraction yield of pigments from black soybean hulls were optimized with Response Surface Methodology (RSM). A mathematical model was established and analyzed to describe the relationships between the studied factors and the response of the total extraction yield of pigments from black soybean hulls. The optimum extraction parameters are as follows: ultrasonic power 80 W, pH1.5 and the ratio of solution to solid 30 mL/g. Under the optimum conditions, the extraction rate of pigments from black soybean hulls can reach 95.6%.