Comparative Nutritional Analysis of <i>Tylosema esculentum</i> (Marama Bean) Germplasm Collection in Namibia

Abstract

Malnutrition is a medical condition caused by an unbalanced diet, typically characterised by stunting and wasting in children. Malnutrition causes approximately a third of all deaths in children between 0-59 months mostly in developing countries. In Namibia, 24% of children under the age of 5 years are stunted while 6.2% are wasted. Tylosema esculentum, commonly known as marama bean is an underutilised legume of high nutritious value. Indigenous to Namibia, marama bean seeds have comparably high protein and lipid content. Marama bean is an appealing crop to Namibia in particular due to its low cultivation demands as it grows in sandy soils with minimal water requirements and no need for fertilisers. Ten accessions of marama bean seeds were analysed for their nutritional composition. The results indicate that ash content was found ranging between 2.13% and 3.46%. Minerals analysed were calcium, iron, magnesium, phosphorus and zinc. Their range of concentrations were 750.1-2306.2 mgkg-1 , 53.9-322.4 mgkg-1 , 1764.1-7415.0 mgkg-1 , 4300.8-5267.9 mgkg-1 and 32.2-48.8 mgkg-1 respectively with no significant difference in concentration among the ten accessions. Correlation analysis of the minerals within the accessions showed that the correlations between zinc-magnesium and zinc-phosphorus concentrations were significantly different as compared to the rest of the pairs for all accessions. When analysed, the maximum and minimum amounts of crude fat and carbohydrates were 29.9%-44.1% and 19.4%-39.0% respectively which were found to not have a significant difference. However, the protein analysis determined that there was a significant difference with PMBC2 (mean content 34.6%) being the most significant accession. Therefore, PMBC2 was found to be the most suitable accession for crop development and domestication. This study's main contribution with respect to the domestication of marama bean was the identification of the most superior accession based on nutritional composition.