Determination of tannin concentrations in african indigenous vegetables, grains and cassava roots from Emuhaya District, western Kenya

Abstract

The studyevaluated tanninconcentrations in four vegetables, three grains and cassava roots as the most common foodstuffs in the diet of local communities from Emuhaya district in western Kenyaand their nutritional health implication. Plant specimens were collected from local arable farms and market centres and their identities confirmed at Maseno University herbarium. Tannincontent was evaluated using the International Phamacopoeia Method.Percent compositionof tannins in the sampled specimens were: 9.49±0.6 for rattle pod (Crotalaria brevidens(Emiroo); Family, Fabaceae), 8.38±0.3 for narrow-leaf bitter-pea(Daviesialeptophylla(Omurere); Family, Fabaceae), 2.49±0.2 for amaranth (Amaranthushybridus(Tsimboka); Family, Amaranthaceae), 0.42±0.04for black nightshade(Solanumnigrum(Lisutsa); Family, Solanaceae), 9.21±0.4 for peanut/groundnut (Arachishypogaea(Tsinjugu); Family, Fabaceae), 8.24±0.4 for sesame(Sesamumindicum(Tsinuni); Family, Pedaliaceae), 8.11±0.2 for finger millet (Eleusinecoracana(Obulee); Family, Poaceae) and 6.99±0.5 for cassava (Manihotesculenta(Emioko); Family, Euphorbiaceae). Solanumnigrumhad significantly the lowest tannin composition profile followed by A. hybridusand M. esculentain that order (P < 0.05). Interestingly, these three plants are preferred in the diet to the rest of the plants. The results provide scientific rationale for dietary exploitationof these plants bythe local communities and may lay down some groundwork for exploiting partially refined products such as peanut butter and a wide range of grades of flour for human consumption and livestock feeds. However, consumption of tannins in the diet may sometimes benecessary for optimal health but caution needs to be taken for their conflicting adverse medical-based nutritional and physiological effects.