Study on Enzymatic Demulsification of the Emulsion from Enzyme-Assisted Aqueous Extraction of Soybean Oil

In order to destablize the emulsion from enzyme-assisted aqueous extraction of soy oil and obtain the high free oil recovery, demulsification efficiencies of α-amylase, cellulose, Alcalase, 7L neutral protease were evaluated. The effect of alcalase and 7L protease on the stability of the cream was respectively investigated by free oil recovery, Zeta potential, viscosity, particle size distribution and mean particle size. The results showed Alcalase and 7L protease obtained the higher free oil yield than others, provided complete conversion of the cream to the free oil. However, compared to 7L protease, Alcalase had the higher free oil yield. 2% 7L neutral protease reached 100% demulsification rate in 60 min, while 1% Alcalase could realize 100% demulsification in the same enzymatic time. Viscosity and zeta potential of the emulsion decreased, aggregation of the oil drop formed after the enzymolysis of Alcalase and 7L protease, which led to a decline of stability of the emulsion. With the increasing of protease concentration and enzymolysis time, correspondingly, viscosity decreased and demulsification rate increased.