[Nutritional value of protein subjected to technologic processing. Changes in content of biologically active amino acids--methionine, cysteine and taurine under the influence of sterilization].

The sterilization effect was analysed on the nutritional value of two protein types (milk/casein) and fish (cod). By chemical-biological method (determination of digestibility, assimilate-ability and growth yield) the level of accessible methionine and cysteine, and taurine level as a metabolite of sulphur-containing amino acids were determined in the liver and urine of experimental animals. Cod protein and casein subjected to technological processing showed lower digestibility, assimilate-ability and growth yield as compared with raw protein. The serum level of biologically active sulphur-containing amino acids methionine and cysteine was lower also. A significant correlation was found between the results of the biological assessment of the nutritional value of protein, and the levels of methionine and cysteine in diet on the one hand, and the content of taurine in the liver and urine of rats, on the other hand. The possibility of assessment of the nutritional value of protein based on urinary taurine level is a simple and non-invasive method based on the metabolism of sulphur-containing amino acids in the organism of humans and animals which encourages for further studies.