Optimization of microwave- assisted extraction technology of soybean isoflavones from black soybean

Microwave- assisted extraction was used to extract soybean isoflavones from black soybean. The influence factors of impacting extraction yield and the optimal extraction conditions were studied by single factor and L9( 34) orthogonal experiment. The results showed that all the factors including solid- liquid ratio,ethanol concentration,microwave power and microwave- heating time had different effects on the yield of soybean isoflavones.And the effect of microwave power was significant( p < 0.05). The optimal conditions were as follows:the 1∶25( g / m L) ratio of solid- liquid,60% ethanol,microwave power was 300 W,extracting for 2min. The yield of soybean isoflavones was up to 0.488% ± 0.01% under these conditions.The method was stable and feasible,which could be applied for the extraction of soybean isoflavones.