Clean and debittered yeast cells biomass and its derivatives, total autolisate and extract, after dehydration (spray dryer), were used in a bioassay with wistar rats for determination of protein nutritive value and evaluation of the impact of the yeast products on the blood serum levels of uric acid, triacylglycerols, total cholesterol and High Density Lipoproteins-cholesterol. Integral cells, total autolisate and yeast extract did not differ statistically (p <= 0.05) regarding Protein Efficiency Ratio and Net Protein Ratio, which were significantly lower than the casein value. The growth promoting capacity was higher for casein, followed by integral cells, yeast extract and total autolisate, in decreasing order of magnitude. Net protein utilization values confirmed the Protein Efficiency Ratio and Net Protein Ratio results. Yeast products protein nutritive value was statistically identical but inferior to casein value. On the whole, the nutritive value of the yeast products protein ranked between 80-85% of the casein value. Uric acid serum concentration increased in the rats fed the diets containing yeast products, but the values remained in the range considered of normality for rats. The diet containing yeast autolisate produced a reduction of the triacylglycerols content, which was not observed in the other diets. For total cholesterol and High Density Lipoproteins-cholesterol all three yeast diets were similar and did not differ from the casein diet.
rats; proteins; nutritive value; saccharomyces cerevisiae; biomass; integral cells; autolisate; extract
