The amount of soluble aggregates formed at the different pH values with or without salt addition was investigated by RPHPLC analysis (Figure 2). The conversion yield of native whey proteins was found to vary from 72% at pH 6.6 to 65% at pH 7.0. Croguennec and co-workers36 reported very similar values upon heating â-lactoglobulin dispersions at 85 °C for 15 min at pH 6.6. The slight decrease of the yield of soluble aggregate formation upon pH increase can be attributed to the increased negative charge carried by the unfolded proteins, preventing further aggregation by repulsive interactions. In addition, the increased dissociation yield of the thiol groups, especially for â-lactoglobulin, at higher pH values might result in an increased probability that the activated non-native intermediate will react and form disulfide bonds that will terminate the propagation of aggregate growth.37Upon addition of sodium chloride, the amount of WPI soluble aggregates markedly increased from 75% at pH 6.0 to 95% at pH 7.0. This increased soluble aggregate amount might result from the charge neutralization of unfolded and reactive whey proteins that could therefore continue to aggregate to larger sizes (as could be explained by the higher turbidity values found in the presence of salt). Hence, whey protein denaturation/aggregation close to neutral pH is mainly characterized by the formation of non-native reactive aggregates via thiol/ disulfide group activation/interchange, whose activated aggregates could further aggregate in the presence of salts due to charge screening