Enhancing the antioxidative capacity and acceptability of Kunnu beverage from gluten-free pearl millet (Pennisetum glaucum) through fortification with tigernut sedge (Cyperus esculentus) and coconut (Cocos nucifera) extracts

Kunnu is an infamous non-alcoholic beverage among the inhabitants of Sub-Saharan Africa. It is a fermented product commonly made from millet, sorghum or corn and relatively cheap when compared to carbonated beverages. This study targets value addition of kunnu by fortification with tigernut extracts and coconut milk to further boost the consumption and acceptance among people of all ages. The beverages were then evaluated for the physicochemical properties, phytochemical content and colour analyses. Folin-Ciocalteu method was used to measure the total phenolic content while the ferric reducing antioxidant potential (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) were used to determine the antioxidant capacity. The unfortified kunnu sample had the lowest pH of 3.24 which was significantly increased upon fortification with tigernut extract and coconut milk. Kunnu samples fortified with tigernut had the highest vitamin contents (28.07 mg/ml) and soluble fiber (8%) when compared to the other samples. The total phenol (0.85 mg GAE/ml) and flavonoids (4.59 mg RE/ml) were also highest when the kunnu beverages were fortified with tigernut extract. Fortification with tigernut and/or coconut milk result in elevated antioxidant potentials determined by ABTS, DPPH and FRAP. There was no significant difference in the taste, viscosity, colour and overall acceptability of the beverages when fortified with tigernut extract. The study revealed that fortification with tigernut and/or coconut milk improves the antioxidative potential of the beverages with very good acceptability. The beverage could serve as a healthy replacement for sugar-laden fizzy drinks.