Pressurized Microwave-Assisted Extraction of Total Isoflavones from Pueraria Lobata

Abstract

The single factor experiment method was used to investigate the effects of microwave power（P）, extraction pressure(p), alcohol mass concentration（x%）, ratio of liquid to solid (l/s), pre-immersed time(τ) and particle size(d) on extraction efficiency of total isoflavones from pueraria lobata by pressurized microwave-assisted extraction technique. Based on the above the Design-Expert 6.0 software was used to carry out a response surface test with three factors (ratio of liquid to solid, pressure and alcohol mass concentration) to optimize the technical conditions and establish the mathematical model. The results show that the optimum technical conditions are: P =700w, p =132.61kPa, x =51.2%, l / s =10.45,τ=2h，d = 80 meshes. Under these conditions the extraction efficiency reaches 98.75% which is 23.5% higher than that by microwave-assisted extraction at atmospheric pressure. The established model (second multivariate regression equation) is consistent with the experiment and can predict the extraction efficiency of the total isoflavones under different technical conditions.