Formation and stability of emulsions of soy protein isolates with different sulfhydryl content

This work evaluated the formation and stability of emulsions prepared with three soy protein isolates with different sulfhydryl content (SHL) and at t wo different pHs (6.00 and 7.00). Solubility (Sol), emulsifying activity in dex (IAE), coalescence (%Coal), surface concentration of proteins (T), and kinetics of the creaming process were determined. The effects of pH and sam ple types or their interaction were significant (p < 0.05) for the four var iables. IAE was little enhanced by the SHL increment, while stability to co alescence decreased. Also, it was verified that <Gamma> is negatively affec ted by the SHL increment. The pH effect on IAE depended on the SHL. When pH decreased, %Coale lowered and Gamma increased. Emulsions destabilized by t he floculation-creaming mechanism more slowly at pH 6.00 than at pH 7.00.