Estimation of protein quality in weaning foods prepared from local raw materials

Abstract

A procedure was developed for calculating amino acid scores for use in predicting protein quality of weaning blends of cereals and legumes. Amino acid composition of selected blends was determined with the amino acid analyser and the results were used to assess the relative accuracy or reliability of the theoretical prediction procedure developed. Calculated protein quality values were found to slightly overestimate true values determined by amino acid analysis. A factor of 0.9 was obtained for converting calculated amino acid scores to assayed values. The relative performance of local legumes and cereals in various possible weaning formulations was evaluated using the blend protein quality prediction procedure, to serve as a quick guide in local weaning formulations. Increasing legume concentration in blends improved the protein quality until a new limiting amino acid was imposed, thereafter reducing the rate of increase in the net protein value of the blend. Poorest quality blends were obtained in mixtures of cereals with groundnut due to the relative inadequacy of groundnut protein to complement cereal amino acids. When used in combination with cowpea, pigeon pea, soybean or winged bean, the groundnut produced better quality blends than when used singly. Soybean, soybean Tempeh and winged bean produced the best quality blends (with cereals) followed by cowpea and pigeon pea in that order. No additional benfits could be derived in using pigeon pea i mixtures with cereals, beyond 20% of the legume concentration. Among cereals, blends containing millet gave the highest net protein values at each level of fortification, followed by maize-containing blends. In spite of its higher protein content over the other cereals, sorghum blends had the least net values