Rat bioassay of the protein nutritional quality of soy‐fortified sorghum biscuits for supplementary feeding of school‐age children

BACKGROUND: Protein–energy malnutrition (PEM) remains a major deficiency disease among children in developing countries. The protein nutritional quality of soy‐fortified sorghum biscuits was evaluated with respect to their potential as a protein‐rich supplementary food. Three isonitrogenous diets based on 50:50 ratio decorticated sorghum:defatted soy flour biscuits, 100% sorghum biscuits, casein, and a protein‐free diet were fed to male Sprague Dawley weanling rats. RESULTS: Protein efficiency ratio (PER) for the sorghum–soy biscuit diet was equivalent to the reference casein diet, and zero for the 100% sorghum diet. Faecal bulk for 100% sorghum diet was 1.5 times higher than sorghum–soy and casein diets. True protein digestibility of the three diets was high—88–95%—agreeing with previous rat studies with sorghum. Biological value and net protein utilization of the sorghum‐soy biscuit diet were similar to the casein diet, but lower than the 100% sorghum biscuit diet CONCLUSION: Notwithstanding limitations of rat bioassay for assessing sorghum food protein quality, the high PER of defatted soy flour‐fortified sorghum biscuits (sorghum:soy 50:50 ratio) indicates they have considerable potential as a supplementary food to young children to alleviate PEM. Copyright © 2011 Society of Chemical Industry