Optimization of separation method of 7S and 11S in soy protein

The conditions for extraction and separation of 11S and 7S fractions from soybean protein were optimized.The factors affecting extraction effect,including extraction solution,extraction conditions,the addition of reducing agent and removal intermediate fraction were improved.The result was investigated by Kjeldahl method and SDS-PAGE,which indicated the defatted soybean meal was extracted with water(pH9.0)at 45℃ for 1h.The meal-to-water ratio was 1∶15 and the meal was extracted twice then by adding reducing agent NaHSO30.01mol/L.The 11S fraction was precipitated at pH6.4.The insoluble intermediate fraction was removed by centrifugation at pH5.4 and 7S fraction was obtained at pH4.8.Under these conditions,the yield and purity of 11S and 7S fractions could be increased than that by Thanh method and Nagano method.