Henningfield M F, Smith S D, Reynolds P A, Garcia S E, Baxter J H
Abbott Laboratories, Ross Products Division, Columbus, Ohio 43215.
J Am Diet Assoc. 1995 Jan;95(1):46-52. doi: 10.1016/S0002-8223(95)00012-7.
Eternal formulas were monitored during their shelf life and beyond expiration date to examine protein quality.
Protein quality was determined by protein efficiency ratio (PER) bioassays and amino acid analyses.
A certified laboratory performed the PER tests according to procedures established by the Association of Official Analytical Chemists and recognized by the US Food and Drug Administration (FDA). The amino acid analyses were performed in our laboratory using validated methods.
Commercially available formulas (Ensure, Osmolite HN, TwoCal HN) that contained protein blends of caseinates or caseinates with soybean protein isolate were studied.
Achievement of protein-quality values greater than or equal to 70% of the fresh reference casein value as determined by the PER method would be consistent with adequate protein quality as described by the FDA. Levels of indispensable amino acids that meet or exceed the standards established by the National Research Council of the National Academy of Sciences are considered high-quality proteins. Levels of amino acids throughout shelf life were compared with published label claims.
Amino acid analyses, which included measurement of tryptophan and total sulfur amino acids, revealed that both fresh and outdated products met or exceeded standards for proteins of high biologic value and were consistent with label claims. The PER values ranged from 90% to 96% of the control diet for fresh product and 82% to 87% for products evaluated after expiration.
The enteral products studied provide high-quality protein throughout the shelf life of the product.
