Speaker
Description
Dairy gels are networks formed by the aggregation of colloidal scale particles, casein micelles, in milk. This class of materials represent a well developed technology for the modulation of sensory properties, storage and transport of milk products, and such technologies may be developed for other food gels. Previously we have examined the equilibrium structure of dairy gels formed by acid and enzymic gelation using ultra-small angle neutron scattering (USANS) and neutron imaging. A comparison of the data with a calculation based on the fractal dimension and single correlation length of the gel network (Teixeira/Chen model) and material composition yields a perspective on the spatial heterogeneity in a representative volume of the gel. An analysis of the gel’s mechanical properties through the interpretation of oscillatory rheology has provided an equivalent fractal dimension. Here we our describe experimental efforts in following the evolution of this fractal dimension and the kinetics of casein micelle aggregation. Two types of small angle neutron scattering have examined use the point by point measurement of Bonse-Hart USANS on the KOOKABURRA instrument (ANSTO, Lucas Heights, Australia) and very small angle neutron scattering VSANS at the Chinese Spallation Neutron Source (Dongguan, China) on an area detector to understand the time course evolution of the network. USANS measurements provide an unequivocal, but with temporally limited temporal resolution, probe of VSANS measurements provide insights into the early aggregation process with superior time resolution. To bridge the spatial resolution between conventional neutron radiography and small angle scattering we have examined gel formation dark field imaging on the BOA and FOCUS beamlines at the Paul Scherrer Institute (Villigen, Switzerland).