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 weight-average degree of polymerization, (x) over bar(w), during renneting of milk at three different concentrations of enzyme and three concentrations of casein, including the normal casein concentration of milk. The change of (x) over bar(w) as a function of time was described using Von Smoluchowski's equation, testing a number of expressions for the aggregation rate constant, k(ij). The best description was achieved when k(ij) was taken as a function of an energy barrier against aggregation that was diminished by the proteolysis of kappa-casein. The initial value of the energy barrier partly depended on the casein concentration, and had a value > 25 k(B)T at normal casein concentration, where k(B) is Boltzmann's constant and T the absolute temperature, When the proteolysis of kappa-casein was complete; the energy barrier was reduced to 11 k(B)T and was independent of casein concentration.