Whey proteins, in whey protein isolate (WPI) and whey protein concentrate (WPC), form gels when heated at concentrations above a critical protein concentration and at temperatures and for times which cause denaturation (Singh2011). The nature of the gels is influenced by the calcium concentration of the whey protein solution. The firmness ofthe gels formed from WPI and WPC at neutral pH has been shown by numerous authors to reach a maximum in therange 2–20 mM Ca2+(as calcium chloride) and then decrease at higher Ca2+concentrations (Lupano et al. 1992).Similarly, in whey protein solutions at 4% (w/w), below the critical gelling concentration, Riou et al. (2011) found that added Ca2+greatly enhanced denaturation/aggregation even with small additions, for example 4 mM, and the effect increased with increased calcium addition up to a maximum at ~80 mM for b-Lg and ~50 mM for a-La. However, at higher added Ca2+levels, ~110 mM, the denaturation/ag gre-gation was partly inhibited. Riou et al. (2011) found that the effect of added calcium on the behaviour of whey pro-teins also varies according to the source of the whey proteins. The enhanced gel firmness with low levels of added calcium chloride is attributable to shielding the electrostaticrepulsion between proteins and forming Ca–protein bridgesin addition to the disulphide and hydrophobic bonds formedwithout added calcium. When calcium is removed by dialysis or rendered unavailable by chelation, firmness of the gelsis markedly decreased (Kuhn and Foegeding 1991). How-ever, when chelating agents are added to WPC with higherthan optimum Ca2+, an increase in gel firmness can be obtained (Smith and Rose 1994); this is presumably due toless inhibition of aggregation by the chelating agents at high Ca2+reported by Riou et al. (2011).