Effect of pre-heating on the foaming properties of whey protein isolate using a membrane foaming apparatus

The effect of the thermal denaturation of whey proteins on the formation, stability and structure of their respective foams was examined. A membrane foaming apparatus, which is a very gentle foaming method, was used to produce the foams. It was shown that the denaturation of the beta-lactoglobulin, the main component in whey protein isolate, strongly improves the foam stability. At a denaturation degree > 70%, it is possible to reduce drainage to a large extent. The image analysis demonstrated that higher levels of denaturation of the proteins, and thus higher viscosities of the protein solution, produced coarser foam textures with larger bubbles. The incorporation of the bubbles was more difficult when the viscosity of the continuous phase was high. (C) 2003 Elsevier Ltd. All rights reserved.