Microbiological evaluation of protein quality withTetrahymena pyriformisW

Abstract

Growth of Tetrahymena pyriformis W in 4 days incubation under highly aerobic conditions was used to evaluate the quality of various proteins. Growth in relation to ammonia N production was taken as the index of efficiency of protein utilization. Relative nutritive values determined by this method (casein = 100) ranged from 0 for raw egg white to about 130 for meat and fish meals. Depressed values were shown for overheated peanut and soybean meals, and an increased value was obtained for gelatin when it was supplemented with tryptophan. The growth inhibitors in raw egg white were inactivated by heating. In general, the relative nutritive values of proteins obtained agreed with ratings for the growing rat.