A new biological method for estimating food protein nutritive value

Abstract

1. A new method has been devised for the nutritional evaluation of food protein quality. The method is analogous to the classical determination of net protein utilization (NPU). The suggested new criterion, the protein utilization by the liver (LPU), expresses the amount of food nitrogen ‘retained’ in the liver as a percentage of the food nitrogen intake. 2. Five different foods, casein, soya-bean protein isolate, maize gluten, wheat gluten, cottonseed meal alone or with supplements of amino acids, a total of thirteen samples, were tested for LPU and NPU in groups of six rats. The correlation coefficient between values for LPU and NPU for all seventy-eight rats was +0.85 and was highly significant.