DETERMINATION OF MOLECULAR-MASS DISTRIBUTION OF FOOD-GRADE PROTEIN HYDROLYZATES BY SIZE-EXCLUSION CHROMATOGRAPHY AND CHEMILUMINESCENT NITROGEN DETECTION

Size-exclusion chromatography (SEC) and chemiluminescent nitrogen dete ction (CLND) were used to estimate the molecular-mass distribution of food-grade protein hydrolyzates. Simultaneous CLND and UV (214 nm) det ection is demonstrated for analytical SEC of an experimental casein hy drolyzate. In order to validate the estimated average M-r values deriv ed from the SEC column data, a preparative SEC separation of an extens ive casein hydrolyzate was pursued. Fractions were collected on a time basis and analyzed by time-of-flight (TOF) mass spectrometry. A plot of ToF M-r vs. SEC M-r indicated that the peptides below M-r of 1200 w ere eluted as estimated by the calibrated preparative SEC column. This paper demonstrates the power of using a dual CLND and UV detection sy stem for analytical SEC analysis of protein hydrolyzates with a calibr ated column.