Determination of molecular-mass distribution of food-grade protein hydrolyzates by size-exclusion chromatography and chemiluminescent nitrogen detection

Abstract

Size-exclusion chromatography (SEC) and chemiluminescent nitrogen detection (CLND) were used to estimate the molecular-mass distribution of food-grade protein hydrolyzates. Simultaneous CLND and UV (214 nm) detection is demonstrated for analytical SEC of an experimental casein hydrolyzate. In order to validate the estimated averageM r values derived from the SEC column data, a preparative SEC separation of an extensive casein hydrolyzate was pursued. Fractions were collected on a time basis and analyzed by time-of-flight (TOF) mass spectrometry. A plot of TOFM r vs. SECM r indicated that the peptides belowM r of 1200 were eluted as estimated by the calibrated preparative SEC column. This paper demonstrates the power of using a dual CLND and UV detection system for analytical SEC analysis of protein hydrolyzates with a calibrated column.