Amino acid Composition, Amino Acid Scores and Predicted Protein Efficiency Ratio of Raw and Cooked African Yam Bean (Sphenostylis sternocarpa)

The amino acid composition of raw and heat processing was analyzed by amino acid analyzer. The patterns of 7 essential amino acids were reported in g per 100 g bean protein and the amino acid score and predicted protein efficiency ratio were calculated and reported. The protein quality of the four products were predicted by calculating protein efficiency ratio. Results indicated that processing had various effects which were in this order: roasting > microwave cooking > conventional cooking. Total amino acid values were 78.25, 67.57, 72.25 and 80.0 g/100 g protein for flour from raw, conventionally cooked, microwave cooked and roasted samples respectively. Essential amino acids namely valine, methionine and phenylalanine in both raw and processed samples were not sufficient to meet human nutritional needs based on FAO/WHO (1991) reference pattern for amino acids. The predicted protein efficiency ratio (P-PER) was 2.26 for flour from the raw sample while P-PER of flour from conventionally cooked, microwave cooked and roasted samples were 2.05, 2.19 and 2.31 respectively. The present study indicated that total and particularly essential amino acids contents and amino acid composition of the flour samples changed by the processing methods. Among them, roasting enhanced the contents of amino acids in comparison to conventional cooking and microwave cooking.