[Biological value of a yeast isolate]

Subject to determination was the biological value of protein separated from food yeast by using chemical, enzymatic (chargeability with proteolytic enzymes) and biological (growing male rattlings-weanglings with the initial mass of 45 +/- 1.0 g) methods. The protein content (with no account of nucleinic acids) in rations balanced as to all the ingredients and energy amounted to 10 per cent. The experiments lasted for 28 days. In spite of good assailability of the isolate with pepsin and trypsin and a quite satisfactorily balanced of its amino acids the anabolic effect of the compound was found to be rather low, viz. PER--1.8; BV--49.1%; NPU--40.3% and in the control (caseine)--2,1; 79.0; 60.2 per cent, respectively. This is attributed to the deficiency in compound of sulphur-containing amino acids and to a relative excess of lysine. The biological value of the isolate amounted to 71 per cent of that of caseine. The method of separating protein from the yeast biomass does not have any noticeable adverse effect on its biological value.