Analysis of Protein Hydrolyzates. 2. Characterization of Casein Hydrolyzates by a Rapid Peptide Quantification Method

Abstract

Casein hydrolysates prepared in the laboratory or purchased from a manufactwer were characterized for the proportion of amino acids in free form, in short-chain (di- and tripeptides) or larger peptides. The hydrolysates were fractionated by size exclusion chromatography on a poly(2-hydroxyethylaspartamide)-silica column (PHEA), and the fractions were analyzed by amino acid analysis. This led to an accurate characterization of hydrolysates which allowed a classification of the hydrolysates according to the extent of hydrolysis and their nutritional quality. A rapid method for quantifying peptides in SE-HPLC fractions was also proposed. It was based on UV absorbance measurement at 230 nm, with a correction for the absorbance of aromatic amino acid measured at three wavelengths (230, 280, and 300 nm)