In this paper, the optimal extraction conditions of soybean isoflavone from defatted soybean meal are searched and the antimicrobial action and antimicrobial mechanism of soybean isoflavone are studied.The optimal extraction conditions from defatted soybean meal are confirmed as follows :60% ethanol, temperature is 70℃, ratio of solvent to material is 18:1, extracting time was 2 hours, twice.The contents of soybean isoflavone is reached 0.45% under the condition. The extraction rate of soybean isoflavone by...