Nutritional evaluation of caseins and whey proteins and their hydrolysates from Protamex

Whey protein concentrate （WPC 80） and sodium caseinate were hydrolyzed by Protamex to 5%, 10%, 15%, and 20% degree of hydrolysis （DH）. WPC 80, sodium caseinate and their hydrolysates were then analyzed, compared and evaluated for their nutritional qualities. Their chemical composition, protein solubility, amino acid composition, essential amino acid index （EAA index）, biological value （BV）, nutritional index （NI）, chemical score, enzymic protein efficiency ratio （E-PER） and in vitro protein digestibility （IVPD） were determined. The results indicated that the enzymatic hydrolysis of WPC 80 and sodium caseinate by Protamex improved the solubility and IVPD of their hydrolysates. WPC 80, sodium caseinate and their hydrolysates were high-quality proteins and had a surplus of essential amino acids compared with the FAO/WHO/UNU （1985） reference standard. The nutritive value of WPC 80 and its hydrolysates was superior to that of sodium caseinate and its hydrolysates as indicated by some nutritional parameters such as the amino acid composition, chemical score, EAA index and predicted BV. However, the E-PER was lower for the WPC hydrolysates as compared to unhydrolyzed WPC 80 but sodium caseinate and its hydrolysates did not differ significantly. The nutritional qualities of WPC 80, sodium caseinate and their hydrolysates were good and make them appropriate for food formulations or as nutritional supplements.