The Net Protein Value of Food Yeast

Abstract
Using the nitrogen balance method, the protein values of 2 samples of food yeast (Torula utilis) and one of brewers' yeast were determined. The Torula yeasts, no. 1084 and no. 3, and the brewers' yeast were found, respectively, to be 88.3, 87.3 and 85.5% digestible, to possess biological values of 48.8, 45.3 and 69.3 and to have net protein values of 21.2, 20.0 and 30.1. The 2 Torula yeasts, the one from England, no. 1084, and the one from Puerto Rico, no. 3, have practically equal nutritive coefficients. The superior net protein value of the brewers' yeast over that of the Torula samples is due exclusively to its higher biological value since the protein (N × 6.25) content and digestible coefficients of the 3 yeast samples are practically the same.