Plasma amino acid response to single test meals in humans. IV. Four low-cost protein supplements evaluated by chemical analysis, rat bioassay and plasma amino acid response.

For supplementary weaning foods, Faffa (Ethiopia), Incaparina (Guatemala), Superamin (Egypt) and Sekmama (Turkey), were studied with regard to protein quality. Three different methods for protein quality evaluation were used. 1. Chemical analysis of the essential amino acid content. Amino acid scoring of the results indicated that the sulphur-containing amino acids were limiting in Faffa (77%); lysine, threonine and isoleucine in Incaparina (77--75%); threonine in Superamin (80%) and threonine and the sulphur-containing amino acids in Sekmama (90%). 2. Standardized nitrogen balance procedure using laboratory rats. The net protein utilization of the four weaning foods were all in the range 56--70%. Methionine supplementation (1 g/100 g protein) did not significantly improve the biological value of the test diets, but resulted in marked decreased levels of blood urea nitrogen (except for Incaparina), and decreased urinary excretion of urea nitrogen compared to total nitrogen excretion (except for Superamin). 3. Single meal plasma amino acid responses in healthy young adults. The responses of the essential amino acids after test meals with the four weaning foods were all within a range considered to indicate a well balanced supply of dietary amino acids, except for marginal deficits of methionine after the Faffa test meals, and isoleucine after the Incaparina test meals.