A NEW SPECTROPHOTOMETRIC APPROACH FOR FOLLOWING THE RELEASE OF CASEINOMACROPEPTIDE DURING RENNETING OF MILK

The new spectrophotometric method was used to study the release of cas einomacropeptide (CMP) as well as its glycosylated (GMP) and non.glyco sylated form during renneting of skimmed raw milk at 3 pH-levels (pH 5 .96, 6.35 and 6.67). The content of GMP in 2 raw milks of different or igin was estimated to 38% and 39% of the CMP, respectively. The releas e of GMP during renneting followed an integrated form of the MICHAELIS -MENTEN kinetics. A 90-98% proteolysis of GMP did correlate to the tim e of visible clotting. The course of CMP showed a characteristic shoul der prior to any visible clotting what is caused by the presence of no n-glycosylated macropeptide. A good correlation was observed between t he release of carbohydrate-free macropeptide and turbidimetric measure ments using undiluted milk emphasizing that the release of non-glycosy lated macropeptide might be a prerequisite for the formation of micell ar gel structures.