Effect of pH and Temperature on the Viscosity of Texturized and Commercial Whey Protein Dispersions

Apparent viscosity (ηa) of texturized whey protein concentrate (tWPC80) produced using supercritical fluid extrusion process was compared with commercial WPC-80 as a function of pH (3.0 to 9.0) and heating temperatures (25 to 80°C). The tWPC80 exhibited shear thinning behavior and yielded 2 to 10-folds higher ηa than commercial WPC-80 at all pH and temperatures studied. The ηa of tWPC80 decreased as pH was increased from 3.0 to 9.0. The ηa of both samples was always higher at pH 3.0 than at pH 7.0 due to acid-induced aggregation in the former. The ability of the tWPC80 to perform as a food thickening agent was also compared with other commercial thickeners. The tWPC80 offers as a desirable ingredient for many food formulations currently utilizing starches and polysaccharides as texture modifying agents.