Optimization of Ultrasound-Assisted Acid Hydrolysis of Total Isoflavones in Radix puerariae Using Response Surface Methodology

Abstract

The present study reports on ultrasound-assisted hydrolysis of total isoflavones in Radix puerariae using hydrochloric acid as catalyst and the influence of different hydrolysis parameters on the yield of puerarin. Based on the single factor test, response surface methodology (RSM, Box–Behnken Design) was used to develop predictive models for simulation and optimization of the hydrolysis conditions in order to increase the yield of puerarin. The optimum hydrolysis conditions were as follows: hydrolysis time of 48 min, hydrolysis temperature of 78°C, ultrasonic power of 180 W and the concentration of hydrochloric acid of 4.6% (v/v). Under these optimal conditions, the concentration of puerarin was increased to 15.92%, which is 19.5% higher than that in the original crude extract. At the same time, compared with the traditional acid hydrolysis, the time needed in ultrasound-assisted hydrolysis is only 45 min, which is 120 min shorter than traditional hydrolysis.