Physicochemical and rheological properties and oxidative stability of oil bodies recovered from soybean aqueous extract at different pHs

Soybean oil bodies (OBs), naturally pre-emulsified soybean oil, have great potentials to be used in foods and cosmetics. In this study, OBs were recovered from soybean aqueous extract at pH 6.8, 8.0, 9.5, and 11.0, and recovered OBs contained decreased extrinsic protein amount and composition with increasing recovery pH. In unheated condition, particle size and viscosity decreased, whereas isoelectric point (pI) and oxidative stability increased in the order of pH 6.8-, 8.0-, 9.5-, and 11.0-OB. By heating, it was observed that 1) coalescence of OBs occurred in pH 6.8-OB emulsion, but not occurred in pH 11.0-OB emulsion; 2) pIs of all OB emulsions increased; 3) pH 9.5-OB emulsion showed the highest viscosity, followed by pH 8.0- and 6.8-OB, and pH 11.0-OB still showed the lowest viscosity; 4) gels were formed from OB emulsions with solid content of 40% except pH 11.0-OB; 5) oxidative stability was greatly improved for all OB emulsions. This study is meaningful for supplying fundamental information for selecting proper conditions for aqueous extraction of soybean OBs.