Processed cranberry bean (Phaseolus coccineus L.) seed flour for the African diet

Abstract

With a view to supplementing protein-calorie in a developing country such as Nigeria, a study was conducted to determine the suitability of a little known crop, cranberry bean (Phaseolus coccineus L.). For this purpose, proximate analyses were done on mineral and amino acid composition of raw and processed seeds (roasted, sprouted, boiled and cooked) using standard analytical techniques. The processing methods showed deviations in nutrients from the raw seeds. Crude fat was found to be reduced by different processing methods, while crude protein was enhanced by roasting and sprouting. Processing significantly (P ≤ 0.05) affected the content of some minerals in P. coccineus seed flour. Roasting and sprouting reduced potassium content by 67.4 and 47.2%, respectively, while boiling and cooking increased the same mineral by 35.0 and 24.9%, respectively. All the processing methods reduced calcium content. Generally, processed cranberry bean seed flour was found to be a good source of essential minerals, and harmful heavy metals such as lead and cadmium were not detected. The amino acid profile revealed that roasting and sprouting enhanced total amino acid (TAA), total essential amino acid (TEAA) and total sulphur-containing amino acid (TSAA), while boiling and cooking reduced TAA, TEAA and TSAA. The limiting amino acid for raw and cooked seeds was Val, whereas TSAA were limiting in roasted, sprouted and boiled seeds. Sufficient proportions of the essential amino acids were retained after processing of the cranberry bean seed to meet FAO dietary requirement, so this crop is considered to be a valuable protein source for the African diet. Key words: African, chemical composition, cranberry bean, domestic processing, flour, Phaseolus coccineus L. seed