Speaker
Prof.
John White
(Australian National University)
Description
A model for foods is to consider them in terms of colloidal composites. Great progress has been made in understanding colloidal systems and their interfaces using x-ray and neutron scattering but especially with contrast variation of one or both of the components. For colloids, the interactions between the components are relatively weak electrostatic and van der Waals forces. Even the major components of some foods, the proteins, are relatively fragile to heat, interfacial stresses and pressure as well as the pH of the system. All of these stresses appear in foodstuff processing as well as compositional variability.
Milk is a substance of relatively constant composition and so will be taken as one of the examples in the lecture. The accessibility of scattering methods to understanding the weak interactions between caseins and inorganic phosphate will be discussed.
A challenge – already resolved for simple colloidal systems – is the use of deuterium substitution for neutron scattering contrast in foods. This is well developed for some proteins and membrane structures but only now being achieved for the caseins in milk. Most proteins are robust to deuteration but others not – this may be a problem to solve.
