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Changes in milk on heating: viscosity measurements

Published online by Cambridge University Press:  01 June 2009

Theo J. M. Jeurnink
Affiliation:
Netherlands Institute for Dairy Research(NIZO), PO Box 20, 6710 BA Ede, The Netherlands
Kees G. De Kruif
Affiliation:
Netherlands Institute for Dairy Research(NIZO), PO Box 20, 6710 BA Ede, The Netherlands

Summary

Skim milk was heated at 85 °C for different holding times. As a result of such heating, whey proteins, in particular β-lactoglobulin, denatured and associated with casein micelles. This led to an increase in size of the casein micelles but also to a different interaction between them. Both these changes could be described by using a quantitative model which was developed for the viscosity of so-called adhesive hard spheres. We applied the model successfully to skim milk and were able to describe on a quantitative basis the changes due to the heat treatment of milk. It was shown that after heating the casein micelles became larger and acquired a mutual attraction. The unfolding of the whey proteins and their subsequent association with the casein micelles appeared to be responsible for these changes. How this reaction influences the fouling of heat exchangers is discussed.

Type
Original Articles
Copyright
Copyright © Proprietors of Journal of Dairy Research 1993

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