Abstract

In this study, an evaluation of the chemical composition, antioxidant activity, functional properties and inhibitory action of the extract of unripe plantain flour on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical was carried out. Chemical analysis of the flour showed that it contained significant quantities of dry matter (48.00 ± 3.96%) and starch (31.10 ± 0.44%) but was low in phenol (1.42 ± 0.03%), protein (3.15 ± 0.042%), ash (5.50 ± 0.42%) and total soluble sugar (0.64 ± 0.001%) (p < 0.05). The antioxidant activity of the extract as determined by the quantities of peroxidase (52 ± 0.00%)  and reducing power tests indicated that the flour had a strong antioxidant activity while the inhibitory capacities of the extract and quercetin on DPPH radical were 78.57% and 5.32ug/ml respectively. Analysis of the phytochemical compositions of the using the Association of Official Analytical Chemists (AOAC) and the gravimetric method of Harbone showed that it contained 1.58 ± 0.04% tannin, 1.82 ± 0.05% saponin, 1.37 ± 0.05% alkaloid and  0.98 ± 0.00% flavonoid. The unripe plantain flour was found to have good functional properties in addition as indicated by the values obtained for water solubility index (3.38 ± 0.007%), water absorption capacity (1.25 ± 0.35g/g) and bulk density (0.94 ± 0.014gml^-1).These findings suggest that unripe plantain could serve as a good source of natural antioxidants with free radical scavenging activity. In addition, it could have a wider utility in alcohol production, food and sugar industries and as a drug binder and disintegrant in pharmaceuticals.

Key words: Antioxidant Activity, Chemical Composition, Functional Properties, Plantain flour, Reducing power, Percentage inhibition.