Kinetics of solvent extraction of soybean isoflavones from soybean meal

In this work, 70% ethanol was used as solvent to extract soybean isoflavones (SI) from defatted soybean meal, and the mass transfer kinetics of SI extraction at temperature in the range of 40°C to 70°C was investigated. According to the Fick's second law, the dynamic model of SI extraction was deduced by using the separation of variables method, and then considering the degradation of isoflavones and the degradation reaction is a first order reaction, the model mentioned was simplified into a modified model. The modified model fits the experiment data well and can explain the fact that at a higher temperature, the isoflavones recovery from soybean meal decreases when the extraction time is in excess of a certain extension. Therefore the modified model can provide the valuable theory basis for the technical design of SI extraction process and the selection of the operation conditions of the process.