Small and large deformation studies of protein gels

Abstract

The rheological behavior of protein gels with different network and strand structures has in a series of studies been investigated to elucidate how the structure of the gel influences its rheological properties. Nondestructive viscoelastic measurements and fracture techniques were used and the different types of structures studied were fine-stranded gels and particulate gels. The influence of spatial inhomogeneities in the network structure was also investigated. The protein gel chosen as the model system was β-lactoglobulin which forms gels on heating and develops different structures depending on pH: a particulate network at intermediate pH (4–6) and a fine-stranded network below and above this interval. It can also form inhomogeneous networks depending on pH or heating rate. The fine-stranded and the particulate gels had totally different mechanical properties. It was shown that the strand structure influenced both the modulus as well as the fracture properties of both fine-stranded and particulate gels. Inhomogeneities induced by a slow heating rate also changed the mechanical properties the gels.