Interactions between milk proteins influence of heat calcium and lactose i. interactions between i whole casein and beta lactoglobulin and ii kappa casein and beta lactoglobulin
Pappas, C.P.
Lebensmittel-Wissenschaft und -Technologie 25(2): 102-112
1992
ISSN/ISBN: 0460-1173 Accession: 007474188
Heat-induced milk protein-protein interactions, as shown by change in their calcium-binding and polyacrylamide gel electrophoresis, were studied. The influence of calcium and lactose on these interactions was investigated. Treating whole casein and .beta.-lactoglobulin in mixed solution at 25.degree. C for 30 min without calcium which, however, was added after treatment, resulted in a decrease in the calcium-binding capacity of the system, compared to that when they are treated separately. Heating this protein solution at 80 or 95.degree. C for 30 min or at 115.degree. C for 10 min, without calcium, resulted in a further decrease of calcium-binding with increasing heating. When calcium was present on heating, the protein mixture showed a decline in calcium-binding with heating, but the overall capacity of the system to bind calcium was increased to that of samples treated without calcium. The presence of lactose in the system during heat treatment caused a further decrease in the calcium-binding at all temperatures tested. Similarly, on heating .vkappa.-casein and .beta.-lactoglobulin together, a reduction in the amount of calcium bound was observed. An attempt to interpret these data in terms of protein-protein, protein-lactose and protein-calcium interactions was made.