Effects of pH, Sodium Chloride and Calcium Chloride on Heat Aggregation of Whey Protein Concentrate and Whey Protein Isolate

Studies on Available Utilization of Whey Proteins Part I

Abstract

To improve utilization of whey protein concentrate (WPC) and whey protein isolate (WPI), effects of pH, sodium chloride (NaCl) and calcium chloride (CaCl₂) on heat aggregation of WPC and WPI were investigated by determining changes in turbidity and viscosity. A time course of turbidity was measured by heating at 2°C/min from 30°C to 95°C. The turbidity of WPC and WPI solution at pH 5.0 was increased from 75°C. The rate of turbidity of WPI solution was higher than that of WPC. Turbidity changes of WPC and WPI solution were observed from addition of 50 mM NaCl and 100mM NaCl, respectively. The turbidity of WPC solution by addition of 1 mM CaCl₂ was increased from about 72°C. The turbidity changes of WPI solution by addition of 1, 2, 5 or 10mM CaCl2 were sharply increased at the temperature from 72°C to 82°C, from 65°C to 75°C, from 55°C to 70°C, and from 50°C to 65°C, respectively. When WPC and WPI solution were heated at 80°C for 15min, viscosity of those was determined. There was little effect of pH on viscosity of WPC and WPI solution. Viscosity of WPI solution added 200mM NaCl was markedly increased by heating. The viscosity of WPI solution was increased by addition of CaCl2, and furthermore it was remarkably changed by heating. These results suggested that desirable coagulates of WPI were formed by adjustment of pH and addition of CaCl₂.