J. Agric. Food Chem. 1997, 45, 3459−3464
3459
Interactions between r-Lactalbumin and β-Lactoglobulin in the Early Stages of Heat Denaturation Douglas G. Dalgleish,* Vinitha Senaratne, and Sophie Francois Department of Food Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
Interactions between whey proteins in mixed systems (10% w/w total protein) containing R-lactalbumin (R-la) and β-lactoglobulin (β-lg) heated at 75 °C for different times were studied using gel filtration chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. On its own, R-la did not form aggregates, and β-lg formed large aggregates with no evidence for intermediates. However, the two proteins interacted to form soluble aggregates, as well as larger particles, by means of both disulfide bonds and hydrophobic interactions. Two main soluble products were identified: high molecular weight components with molecular masses in excess of 300 000 Da and intermediate aggregates with molecular weights in the region of 100 000 Da. The aggregation process was substantially affected, both quantitatively and qualitatively, by the relative proportions of R-la and β-lg: when the weight fraction of R-la in the mixture was
