Proteolysis and aggregation of casein micelles treated with immobilized or soluble chymosin

Summary The relationship between extent of κ-casein proteolysis and aggregatability of milk casein micelles has been studied using chymosin either bound to porous glass supports or free in solution. Both enzyme preparations demonstrated that, overall, 86–90 % of the κ-casein had to be destroyed before any aggregation could occur. Based on these results, a mathematical model of chymosin action on casein is described involving (i) the attack on κ-casein by chymosin, via a Michaelis–Menten mechanism (ii) the probability that sufficient κ-casein on any micelle is destroyed to allow aggregation, and (iii) the aggregation of para-casein micelles by a von Smoluchowski mechanism.