PROTEOSE PEPTONES AND PHYSICAL FACTORS AFFECT FOAMING PROPERTIES OF WHEY-PROTEIN ISOLATE

Effects of peptides and nonprotein components of whey on whey protein isolate (WPI) were studied using a differential pressure method. Decay of WPI foam followed biphasic first-order kinetics, but was affected by solution conditions. WPI foam stability exhibited two pH optima (5.0 and 8.5). Addition of 0.02-0.15M NaCl progressively decreased foaming capacity and foam stability. Addition of 0.01-0.2% proteose-peptones caused a sharp decrease in foam stability, but did not affect WPI foaming capacity. Foam stability was increased by addition of up to 20% lactose. Removal of proteose-peptones should greatly improve foaming properties of whey proteins.