Protein and salt effects on Ca2+-induced cold gelation of whey protein isolate

Increasing whey protein concentration (from 6 to 10% w/v) decreased gel opacity but increased gel strength and water-holding capacity (WHC). Increasing CaCl2 concentration (from 5 to 150 mM) increased gel opacity and gel strength at the high protein concentration (i.e., 10%). However, it lowered gel strength at protein concentration <10%. Young's modulus and distance to fracture values indicated that gels were most rigid at 30 mM CaCl2, at which point the extent of aggregation (measured by turbidity) was the highest. Increasing CaCl2 concentration from 5 to 150 mM slightly affected the WHC of Ca2+-induced gels. Protein concentration was the major factor in determining fracture properties and WHC.