DETERMINATION OF MOLECULAR MASS DISTRIBUTIONS OF WHEY-PROTEIN HYDROLYSATES BY HIGH-PERFORMANCE SIZE-EXCLUSION CHROMATOGRAPHY

Two high-performance size-exclusion chromatographic columns (Superose-12 HR 10/30 and Superdex-75 HR 10/30) were compared for their use in the determination of the molecular mass (M(r)) distribution of whey protein hydrolysates. For calibration 21 reference compounds of known M(r) (ranging from 500 to 68 000) were used by applying two procedures for least-squares curve fitting. Based on the calibration graphs constructed. three apparent-M(r) regions were arbitrarily assigned: M(r)(app) <5000, 5000-10 000 and >10 000. Different results for the M(r) distributions of the whey protein hydrolysates were obtained with the two columns. This was mainly due to a difference in peak resolution. which was better for the Superdex-75 column in the M(r) region relevant for the major whey proteins and their hydrolysates. The results were also dependent on the mode of calibration curve fitting used.