STUDY OF THE EVOLUTION OF CASEIN MICELLE SIZE DISTRIBUTION AFTER RENNETING BY MEANS OF QUASI-ELASTIC LIGHT-SCATTERING

Changes in size distribution of casein micelles, during the primary phase of rennet coagulation, were determined by particle size analysis using quasielastic light scattering of suspensions of skim milk, in a modified Jenness and Koops solution. Simultaneously, continuous turbidity measurements were carried out. Immediately after renneting, turbidity and mean size of casein micelles decrease (by 5-6%), primarily through a decrease in the size of the smaller micelles. After this first step, which can be described as the enzymic phase, an increase in turbidity and an increase in size distribution of the smaller particles was observed. It can be hypothesised that aggregation begins while larger micelles are still in the enzymic phase. Finally, the entire size distribution shifts towards large aggregates.