KINETICS OF THE RENNETING REACTION FOLLOWED BY MEASUREMENT OF TURBIDITY AS A FUNCTION OF WAVELENGTH

In order to describe the kinetics of rennet coagulation, measurements of turbidity as a function of wavelength were used to determine the we ight-average degree of polymerization, (x) over bar(w), during renneti ng of milk at three different concentrations of enzyme and three conce ntrations of casein, including the normal casein concentration of milk . The change of (x) over bar(w) as a function of time was described us ing Von Smoluchowski's equation, testing a number of expressions for t he aggregation rate constant, k(ij). The best description was achieved when k(ij) was taken as a function of an energy barrier against aggre gation that was diminished by the proteolysis of kappa-casein. The ini tial value of the energy barrier partly depended on the casein concent ration, and had a value > 25 k(B)T at normal casein concentration, whe re k(B) is Boltzmann's constant and T the absolute temperature, When t he proteolysis of kappa-casein was complete; the energy barrier was re duced to 11 k(B)T and was independent of casein concentration.