Influence of pure gum on the physicochemical properties of whey protein isolate stabilized oil-in-water emulsions

The effect of pure gum (PG) on the properties of oil-in-water emulsions prepared with whey protein isolate (WPI) was studied at different pH (3-7). The mean particle diameters, turbidity, rheological properties and stability of the emulsions stabilized by the WPI/PG mixture were evaluated. The results showed that the emulsion prepared with WPI/PG had a small particle size and good stability, because the WPI/PG mixture created a relatively thick surface layer, reducing interactions between droplets through steric repulsion. All the emulsions exhibited shear-thinning behaviors at tested shear rates in the range 0.1-300 s(-1), the apparent viscosity of WPI/PG emulsions increased with increasing the PG concentration under different pH. A viscosity hysteresis phenomenon was observed in the process of heating up, which meant that the apparent viscosity was not a single-valued function of temperature. The emulsions prepared with WPI/PG (pH 3, 6% PG) were more resistant to environmental stress than those coated with WPI/arabic gum (AG). The experimental results have implications for the development of emulsion-based delivery systems for use in food and beverage products. (C) 2016 Published by Elsevier B.V.