A mechanism for the chymosin-induced flocculation of casein micelles

The chymosin-induced flocculation of casein micelles of bovine milk can be explained and calculated in terms of three relationships, which are (i) the action of chymosin upon the kappa-casein of the micelles; (ii) the probability that a micelle, with a given proportion of its kappa-casein destroyed, will aggregate, and (iii) the aggregation of micelles by a Smoluchowski mechanism. Details of the calculations are given, and the theory is shown to be in good agreement with experimental observations of the dependence of the clotting time with variations in enzyme and substrate concentrations.