Interactive effects of factors affecting gelation of whey proteins

The individual effects of heating time (15-120 min), pH (3-9) and NaCl (0-2M), sucrose (0-30% w/v) and protein (10-30% w/v) concentrations on the strength, turbidity and water holding capacity were investigated on a commercial whey protein concentrate (WPC, 75% protein) when heated at temperatures ranging from 65 to 90 degrees C. Interactive effects were investigated using a four-variable, five-level central composite rotatable design (CCRD) analyzed by response surface methodology (RSM). Gel strength (GS) and water holding capacity (WHC) increased with protein concentration, heating temperature and time. Increasing sucrose concentration decreased GS but increased WHC. Increasing NaCl concentration increased GS and WHC below pH 5 but resulted in weaker gels at high PH (>7).