Factors that affect the aggregation of rennet-altered casein micelles at low temperatures

The effects of temperature, CaCl₂ concentration, pH and ionic strength of milk on the aggregation of casein micelles in milk renneted at 15°C were studied using particle size analysis determined by laser-light scattering. The rate of aggregation of rennet-altered casein micelles became significantly slower on reducing the temperature of renneting from 30 to 10°C. At 15°C, the rate of aggregation of rennet-altered casein micelles increased significantly on adding CaCl₂, on reducing the pH of renneted milk or on adding NaCl (up to 50 mm). These results indicate that particle size analysis can be used successfully to study the aggregation of rennet-altered casein micelles.