The formation of heat-induced protein aggregates in whey protein/pectin mixtures studied by size exclusion chromatography coupled with multi-angle laser light scattering detection

The molecular weight (MW) distribution of whey proteins (WP) mixed with various pectins was investigated using size exclusion chromatography (HPSEC) combined with multi-angle laser light scattering (MALLS). Samples were prepared with 1, 2, 5, 8% WP and 1% pectin. Mixtures were studied at pH 6.0 and CaCl2 concentrations of 0, 5, 10 mM. Aggregate formation was determined after heating at various temperatures. The interactions between WP and low methoxyl pectin were observed before heat treatment. In the absence of calcium, mixing pectins with WP increased the average molecular weight of the aggregates, but the degree of methoxylation of pectins did not affect the MW distribution of the aggregates. On the other hand, in the presence of calcium, low and high methoxyl pectins generated different molecular weight distributions. In addition, the presence of low methoxyl pectin seemed to have a protective effect on WP, as the aggregates showed a smaller molecular weight and a smaller peak.