Controlling the denaturation and aggregation of whey proteins using κ-casein and caseinomacropeptide
Gaspard, Sophie J.
University College Cork
Whey proteins ingredients are extensively used in a variety of product formulations such as dairy beverages, infant formula and sport nutritional beverages, due to their nutritional and functional properties. Dairy protein-containing beverages are thermally processed, typically to ensure microbiological safety. However, whey proteins denature and aggregate at temperatures greater than 60°C, which can lead to fouling of industrial equipment and/or uncontrolled gelation, depending on formulation and heating conditions. The presence of caseins has been previously reported to limit the extent of aggregation of whey proteins. The objective of this study was to investigate the effect of κ-casein and caseinomacropeptide (CMP) on the denaturation and aggregation of whey proteins, with a view to developing practical strategies for controlling whey protein denaturation and aggregation for ingredient applications. This study demonstrated that both κ-casein and CMP have the ability to improve the heat stability of whey proteins. The inclusion of κ-casein reduced the size of the aggregates of whey protein after a first heat treatment (90°C for 25 min at pH 7.2) and enhanced their solubility during subsequent heating (90°C for 1 h at pH 7.2). The presence of CMP during heating increased the temperatures of denaturation and gelation of whey proteins and prevented the formation of solid whey protein gels when combined with a low heating rate. The presence of CMP also resulted in a lower turbidity of whey protein solutions after heating and an enhanced solubility of whey protein aggregates. The effect of glycosylation of CMP on the denaturation and aggregation of whey proteins was pH-dependent; a transition occurred at pH 6, below which the glycosylation of CMP reduced its stabilizing properties. This thesis provides new insights into the interactions of whey proteins with κ-casein and CMP, with potential for novel applications in improving the heat-stability and solubility of whey proteins. The outcomes of this study have applications for the manufacture of clear, heat-stable beverages containing whey proteins.
Whey protein , Caseinomacropeptide , Heat stability , Denaturation , Aggregation , Chaperone-like activity , Kappa-casein
Gaspard, S. J. 2019. Controlling the denaturation and aggregation of whey proteins using κ-casein and caseinomacropeptide. PhD Thesis, University College Cork.