Gelation of casein micelles in β-casein reduced milk prepared using membrane filtration

The gelling behaviour of these samples, reconstituted to the original casein volume fraction, was examined using rheology and diffusing wave spectroscopy. When compared to the original skim milk it was found that there were no statistically significant differences in gelation behaviour during acidification, but differences were noted in gelation time and final stiffness modulus for samples undergoing renneting. These differences were attributed mostly to the changes in ionic composition, as when the serum composition of the retentates was re-equilibrated against the original skim milk by dialysis; the gelation behaviour of the samples was comparable to that of skim milk. The results clearly indicate the importance of the milk's overall ionic balance in the early stages of aggregation of rennet-induced gelation of milk.