Chemical Composition and Bioavailability of Zinc and Iron in Kunu-Zaki, a Nigerian Traditional Beverage

Abstract

Abstract. The effect of processing (germination and fermentation) on the chemical composition (proximate, mineral and phytochemical contents) of a Nigerian traditional beverage, kunu-zaki made from sorghum (Sorghum bicolor) grains with the addition of sweet potato (Ipomonea batatas) paste were studied. The bioavailability of Zn and Fe in the beverage were also assessed using phytate, Zn, Ca and Fe molar ratios. Processing of sorghum into kunu-zaki significantly (p<0.05) increased its ash (26.32 %), Na (21.28 %), Ca (20.59 %), Fe (21.62 %), Zn (13.43 %), flavonoids (11.11 %) and alkaloids (30.00 %) contents, but decreased its protein (-43.75 %), fiber (-28.57 %), phenols (-43.80 %), saponin (-62.6 7%), tannin (-43.80 %), oxalate (-33.33 %) and phytate (-60.27 %) contents. Addition of sweet potato paste to kunu-zaki apparently aided in enhancing its chemical composition. The combination of germination and fermentation as processing techniques were better than germination alone in significantly (p<0.05) improving the bioavailability of Fe and Zn, and reducing the anti-nutrient content of kunu-zaki, in comparison with both raw and germinated sorghum grains. In conclusion, the kunu-zaki had low contents of protein and fiber, adequate arrays of other functional nutrients and potentially high bioavailability of Fe and Zn.