Influence of Hydrogen and Calcium Ion Concentrations, Temperature, and Other Factors on the Rate of Aggregation of Casein

Abstract

The rates of aggregation of 1% whole casein, a-casein, mixtures of a-and [beta]-casein, and pepsin-paracasein, produced by the addition of calcium chloride at pH 6.3, were studied at 25, 30, and 35[degree]; the rates of aggregation of B-casein alone were studied at 30 and 31[degree]. Temperature coefficients for the rate of aggregation are quite high (> 14 per 10[degree]). Similar studies were performed with casein to which phosphate was added, with casein plus citrate, with a mixture of a- and [beta]-casein (31), and with casein aggregated without calcium chloride at pH 5.5. In addition, the aggregation of whole casein by CaC12 was studied from pH 7.9 to 5.5, at concentrations of casein of 0.2 to 1.5%, and the effect of several concentrations of NaCl on the aggregation determined.