Controlling the denaturation and aggregation of whey proteins using κ-casein and caseinomacropeptide
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Date
2019-12
Authors
Gaspard, Sophie J.
Journal Title
Journal ISSN
Volume Title
Publisher
University College Cork
Published Version
Abstract
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.
Description
Keywords
Whey protein , Caseinomacropeptide , Heat stability , Denaturation , Aggregation , Chaperone-like activity , Kappa-casein
Citation
Gaspard, S. J. 2019. Controlling the denaturation and aggregation of whey proteins using κ-casein and caseinomacropeptide. PhD Thesis, University College Cork.