Whey protein nanofibrils: kinetic, rheological and morphological effects of group IA and IIA cations

Abstract

Self-assembly of whey proteins into amyloid-like fibrils during heating at pH 2 and low ionic strength is sensitive to the presence of NaCl and CaCl2. Our earlier work established that at 10 - 120 mM of these salts speeds up self-assembly and favours short, flexible fibrils over long semiflexible fibrils in a way that depends on cation concentration and cation type. Here we explored how other mono- and divalent salts affected fibril morphology and the rheology of fibril dispersions. Divalent salts (MgCl2, CaCl2, BaCl2) had much stronger effects than monovalent salts (LiCl, NaCl, KCl) on gelation kinetics, and differences between salts of the same type were not large. No marked effects of salt type on fibril morphology were evident, but there were subtle differences in the size and extent of fibril networks with mono- vs. divalent salts, which may explain differences in bulk rheology.