Comparative effects of extraction methods on functional and structural features of subunits from 11S soy protein fraction

The aim of this work was to carry out the effects of AOT reverse micelle (RM) method on the functional and structural properties of basic and acidic subunits from 11S soy protein fraction. SDS-PAGE result showed that the purity of acidic and basic subunits prepared by RM (80.14% and 85.90%, respectively) was the higher than that of the isoelectric point cold sink (70.11% and 63.96%, respectively). Interestingly, there were significant differences in the secondary structure between subunits from two methods. Acidic subunits by two methods had similar solubility profiles, showing the higher solubility at pH 2.0–4.0 or 6.0–12.0, while the basic subunits had considerably lower solubility with the minimum at pH 8.0. The solubility, water absorbing capacities, foaming and emulsifying properties of subunits prepared by RM at different pH values and NaCl concentrations were significantly higher than that of IP. These results suggested that the acidic and basic subunits purified by RM had the better functional properties. RM might be an effective method to purify high quality protein for application in the food industry.