ABSTRACT
The rat balance technique is the most practical and relatively inexpensive in vivo method for predicting digestibility of individual amino acids in human foods. Protein digestibility is usually measured from the quantity of nitrogen or amino acids released by the enzymatic hydrolysis of protein sources. The lysine digestibility values obtained by the in vivo method exhibited a highly significant correlation with lysine availability values obtained by a chemical method using Fluorodinitrobenzene or those obtained by an animal bioassay. As a part of the USDA organized collaborative study on protein quality measurement, digestibility of protein and amino acids in 19 food products was determined by the rat balance and in vivo enzymatic methods. The rat balance method appeared to be more suitable than in vivo methods for determining digestibility of protein and individual amino acids in human foods for regulatory purposes.
