Caseinomacropeptide monitoring by capillary zone electrophoresis (CZE) andinterpretation of structural modifications during the primary clotting phase of milk

A Capillary zone electrophoresis (CZE) procedure was used to detect Caseino macropeptide (CMP) formation during the primary clotting phase of milk. Flu orescence spectroscopy was used to give more information on the interrelati on between structural modifications of milk proteins and primary clotting p hase, monitored by tristimulus colorimetry. Different coagulation tests wer e carried out on different days using reconstituted skim milk powder, as st andard substrate, and the same liquid calf rennet solution. CZE, tristimulu s colorimetry and fluorescence spectroscopy were performed in parallel ever y day. Clotting time was calculated by using both a Formagraph instrument a nd visual observation. Techniques used were able to detect the same critica l points associated with the sequence of structural modifications and confo rmational changes occurring on casein fractions. The CZE method was suitabl e to identify and quantify CMP during the whole coagulation phase. The fluo rimetric method was able to detect conformational changes in milk proteins during the coagulation process. Tristimulus colorimetry results were confir med. Furthermore, it was possible to confirm the relationship between CMP f ormation and structural modifications on the casein micelle surface.