The kinetics of the rennin-casein reaction in abnormal cow's milk and milks of some other species and of the action of rennet substitutes on normal cow's milk

Abstract

SummaryIn earlier papers it was shown that the fall in viscosity of milk and caseinate solutions acted on by rennet, follows a first-order reaction equation. The reaction rate constant has been found to be independent of the source of the caseinate substrate used. This seems to be true not only for caseinate from normal cow's milk but also from colostrum, slow-clotting cow's milk and even the milk of buffaloes, sheep and probably goats.With solutions of caseinate from sow's milk the reaction kinetics and the proportional viscosity loss were similar to those of cow's caseinate but the rate constants were much lower. Rennet showed no measurable reaction with human, whale, mare or rhinoceros caseinates but produced a constant rate of fall in the viscosity of a camel caseinate for more than an hour from rennetting.Vegetable and microbiological rennet substitutes also produce a fall in the viscosity of sodium caseinate and the reactions follow first-order kinetics. They differ from cheese rennet in that the proteolysis involved is stronger and is not as limited as that of rennin since they attack at least twice as much of the casein ensemble. This might suggest a mixture of enzymes but since the proportionality between enzyme concentration and k1 was very close this seems unlikely.