STRUCTURAL CHARACTERISTICS AND FOAMING PROPERTIES OF BETA-LACTOGLOBULIN - EFFECTS OF SHEAR RATE AND TEMPERATURE

The main purpose of this study was to determine the extent to which th e process of foaming changes the structure ob beta-lactoglobulin (beta -Lg). beta-Lg unfolded while existing as a foam, but changes in confor mation were reversible upon collapse of the foam. A plot of the overru n (a measure of air incorporation in the foam) for beta-Lg foams (pH 7 ) versus temperature (3-45 degrees C) was a sigmoidal curve that resem bled a two-state denaturation curve. Foaming properties were influence d by temperature and pH, which was attributed to differences in protei n structure, in diffusion rate and in the number of molecules in solut ion for beta-Lg at pH 9 as compared to pH 7. There was a strong correl ation (r > 0.9) between the secondary structure of beta-Lg in solution and the observed foaming properties. A direct link between the struct ure of beta-Lg in solution and its foaming properties was established.