Comparative Review of Crude Protein and Amino Acids of Leguminous Seeds Grown in Nigeria

Legumes are some of the low–priced sources of protein–rich foods that have been found important in alleviating protein malnutrition especially in developing countries. Amino acids are the basic structural building units of proteins. They form short polymer chains called peptides or polypeptides which in turn form structures called proteins. The most common methods of determining nitrogen in foods are Kjeldahl, Formol titration, Dye–binding, Lowry, Biuret and Spectroscopic methods while amino acid composition is usually determined using ion–exchange chromatography on hydrolyzed and derivatized protein in food material. Crude protein and amino acid composition of some Nigerian leguminous seeds were critically reviewed in this write up. The selected legumes are; Cajanus cajan, Glycine max, Vigna unguiculata, Arachis hypogea, Vigna subterranea, Kerstingiella geocarpa, Sphenostylis sternocarpa, Phaseolus coccineus, Phaseolus lunatus, Citrulus vulgaris and Phaseolus vulgaris. The review shows that the protein content of legumes varies between 11.6 – 52.6%. The most abundant amino acids are glutamic and aspartic acids. The total essential amino acids (TEAA) range between 41.28 – 68.85%, total non–essential amino acids (TNEAA) range between 31.50 – 58.72% and total acidic amino acids (TAAA) between 14.30 – 40.47% for all the legumes reviewed. Generally, leguminous seeds are good sources of most of the essential amino acids therefore they are highly suitable for the fortification of cereal products mostly used as weaning foods for children in most African countries.