FACTORS AFFECTING THE DENATURATION AND AGGREGATION OF WHEY PROTEINS IN HEATED WHEY-PROTEIN CONCENTRATE MIXTURES

Whey protein concentrate (65% protein) mixtures, alone or in the presence of NDM, were heated at 66 and 71 degrees C for up to 120 min to yield 16, 25, and 35% TS to simulate the formulation of a nutritional product. Addition of low heat NDM to a whey protein concentrate mixture to yield 35% TS resulted in 6 and 20% denaturation after 120 min and 27 and 83% in the whey protein concentrate mixture (16% TS) at 66 and 71 degrees C, respectively. The effects of Ca and pH on whey protein denaturation and aggregation (66 degrees C) were also studied. A whey protein concentrate mixture (16% TS) dialyzed against simulated milk ultrafiltrate containing 0 to 9 mM Ca and heated (66 degrees C); the mixture was progressively more denatured and formed less soluble aggregate and more insoluble precipitate as the Ca increased. When the whey protein concentrate mixture (16% TS) was heated (66 degrees C) at increasing pH (5.8 to 7.0), whey protein denaturation and insoluble precipitate increased. The alpha-LA denatured more extensively than beta-LG at 66 and 71 degrees C.