CHARACTERIZATION OF PROTEIN HYDROLYSATES PREPARED FOR ENTERAL NUTRITION

A method is described for the comprehensive characterization of protein hydrolysates for enteral nutrition. It includes (1) gel filtration on a 0.9 x 250 cm column of Sephadex G-25F eluted with 5% acetic acid, to prepare pools; (2) amino acid analysis with and without acid hydrolysis to determine the amounts of peptide bound and free amino acids; (3) reaction with TNBS to determine the amount of NH2-terminal groups; and (4) calculation of number-average peptide size of pools from TNBS and amino acid data. The preparation of three hydrolysates of casein with pancreatic enzymes on the industrial scale (5000 L) is described. The number-average peptide size distribution of hydrolysate B, Hydrocase, was 18 % free amino acids, most of which were essential; 62 % peptides containing 2-9 residues; and 20% peptides containing 10-40 residues. The number- and weight-average peptide size distribution of Hydrocase is similar to that reported by the manufacturer of Peptamen, and both differ from the casein hydrolysate in Pregestimil and Nutramigen reported by the manufacturer to contain 50 % free amino acids by amino acid analysis.