Fig. 2 presents monomodal particle size distributions of whey protein dispersions. Distribution curves of unheated and heated up to 70 °C dispersions comprised almost the same particle sizes with a slight shift to higher sizes at higher temperatures of heating. Heating at 80 °C definitively moved distribution curves to higher protein sizes; the largest aggregates reached 1281 nm for 80 °C, 1484 nm for 90 °C and 1718 nm for 95 °C. Preheating of protein dispersions above 70 °C resulted in whey protein denaturation and extensive protein aggregation. Studies on whey protein concentrates showed that, regardless of the source of WPC, denaturation temperature ranged from 75.4 to 76.1 °C, and this is consistent with presented data (Patel and Kilara, 1990).