Casein Interactions: Does the Chemistry Really Matter? - Food Colloids: Self-Assembly and Material Science - page 155

Chapter 10
Casein Interactions: Does the Chemistry
Really Matter?
David S. Horne, 1 John A. Lucey 2 and Jong-Woo Choi 2
1 HANNAH RESEARCH INSTITUTE, AYR, SCOTLAND KA6 5HL,
UK
2 DEPARTMENT OF FOOD SCIENCE, UNIVERSITY OF WISCONSIN,
1605 LINDEN DRIVE, MADISON, WI 53706, USA
10.1 Introduction
'Soft matter' was a term first used in 1991 by Pierre-Gilles de Gennes in his
acceptance address of the Nobel Prize for Physics. Since then the study of soft
condensed matter has become a major growth area in physics, attracting
significant funding worldwide. This sub-discipline encompasses the topics of
colloids, polymers and surfactants, mainly in the high concentration region.
While research activity in the area has undoubtedly grown in the intervening
years, it would probably not be unfair to say that some research groups already
working on these topics simply 're-badged' themselves to jump on the soft
matter bandwagon.
Physics tends to be a subject where generic, unifying and often simplifying
principles are sought to describe the properties and behaviour of the systems
under study. The physics of soft condensed matter is no exception to this rule.
In this article we revisit the subject of casein interactions, and challenge the
validity of extending some of the simplifying assumptions of soft matter physics
to the description of the behaviour of casein-containing colloidal systems.
In reality, we demonstrate here that there is a higher level of complexity to
the interactions of the caseins in the casein micelle than a naı¨ ve application of
any individual soft condensed matter theory would allow. In the development
of any model there should arise questions as to how robust are its theoretical
underpinnings and how can its premises and predictions be challenged. Two
alternative models of the casein micelle provide a significant cross-linking role
for calcium phosphate. Here, using the known stoichiometry of micellar
calcium phosphate and some arguments as to interaction motifs in the caseins,
we estimate the number of casein molecules interacting with each calcium
phosphate nanocluster in the casein micelle.
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