Chemical composition of marama bean ( Tylosema esculentum)—A wild African bean with unexploited potential

Abstract

Marama bean is an underutilized legume which grows wild in Southern Africa and forms part of the diet for the indigenous population. The seeds are rich in lipid and protein, and have the potential to improve nutrition and increase food security for people living in these rural areas. Sixteen samples of marama beans from Botswana, Namibia and South Africa harvested in 1990–2008 were examined for chemical composition. The nutrient content on dry matter basis was: protein 29–38%, lipids 32–42%, dietary fiber 19–27% and ash 2.5–3.7%. In general, beans from South Africa had higher content of protein and ash compared to beans from Botswana and Namibia. The vitamin E isomers α-, β- and γ-tocopherols were found at levels of 14–48, 1.1–3.3 and 59–234 μg/g, respectively. In general, beans from Namibia contained the highest amount of vitamin E. The marama bean had a mineral content similar to that of peanut and approaching that of soybean, and is a good source of the important trace-elements Zn and Fe. The three lignans secoisolariciresinol, lariciresinol and pinoresinol were present in the marama bean. Additionally, the marama bean did not seem to contain any of the potent allergens found in lupine and peanut, and it was not cyanogenic.