Protein changes in stored ultra-high-temperature-treated milks studied by capillary electrophoresis and high-performance liquid chromatography

IDF Symposium on Heat Treatment and Alternative Methods, SEP 06-08, 1995The evolution of direct and indirect ultra-high-temperature-treated milk during storage is studied. Capillary electrophoresis and HPLC analysis of whey is performed. Both techniques allow the quantitation of R-lactalbumin and â-lactoglobulin, providing comparable results at the beginning of the storage and making it possible to estimate the thermal treatment to which milk has been subjected. Besides, the capillary zone electrophoresis method allows differentiation between the proteolysis products caused by plasmin and by some proteases from psychrotrophic bacteria. Isoelectric focusing of the casein fraction allows identification of the degradation products originating from both types of proteases.We thank Dr. C. San José for kindly providing the P. fluorescens B52 protease. Ms. C. Talavera is thanked for excellent technical assistance.Peer reviewe