Use of cold microfiltration to produce unique beta-casein enriched milk gels

Bovine milk was modified using cold microfiltration to produce beta-casein enriched fractions with unique gelation properties. Skim milk at 4 degrees C was microfiltered using membranes with pore diameter of 0.2 mu m, 0.1 mu m, or 100 000 g.mol(-1) MWCO. Resulting permeates were filtered again using membranes with 10 000 g.mol(-1) MWCO to create retentates with 9% solids t hat were used in the gelation study. Ash, calcium, lactose, solids, and pro tein contents of all fractions were monitored to determine separation trend s. Cold microfiltration significantly reduced the casein:whey protein ratio and increased the beta-casein:alpha(s)-casein ratio in the retentates from the second filtration; the smaller the pore size of the initial separation membrane, the greater the change in the ratios. When treated with glucono- delta-lactone and rennet, the beta-casein enriched fractions produced using the 0.2 and 0.1 mu m membranes formed softer gels that had greater syneres is and hydration, and lower water holding capacities than skim milk gels.