Formation of Whey Protein Polymers: Effects of a Two‐step Heating Process on Rheological Properties

Whey protein polymers were obtained by two‐step heating of whey protein isolate (WPI) solutions with or without change of pH or protein concentration. Rheological properties of polymer solutions were studied. Viscosity of solutions heated then diluted was about 6 times higher than viscosity of equal concentration solutions heated directly. A second heating at a lower pH resulted in higher viscosity. Solutions were generally thixotropic and pseudoplastic; however, dilatant and rheopectic behavior was also observed. A 4% WPI solution could be converted to a polymer solution with a viscosity comparable to the viscosity of 1% carbohydrate hydrocolloids.