| Abstract: | A series of biochemical and nutritional studies was performed in order to establish the reasons for the poor nutritional quality of the new soya-protein isolate SP55. Moist heat treatment which destroyed the substantial residual anti-tryptic activity present in the SP55 fraction, did not improve the nutritive value of the protein as indicated by rat feeding tests. Furthermore, partial in-vitro-enzymic digestion by papain or by pancreatin of SP55 prior to rat feeding did not alter the poor performance of the preparation. Amino acid analysis indicated that the protein was deficient in several essential amino acids. Subsequent rat feeding studies showed that the nutritional quality of the protein can be highly upgraded by supplementation with sulphur-containing amino acids, tryptophan and threonine. |
