Chemical Composition, Antioxidant Capacity and Total Phenolic Content of the Flours Obtained from Cow Pea (Vigna ungualata) Varieties Commonly Consumed in Nigeria

Aim: To determine the proximate, mineral composition, antioxidant capacity and total phenolic content of the flours of four varieties of cow pea commonly consumed in Nigeria and to examine the influence of the colour of the beans’ hull on the antioxidant capacity of the bean varieties.
Place and Duration of Study: The experiments on proximate and mineral composition were performed in Chemistry Laboratory of Ekiti State University, Ado-Ekiti while those on antioxidant capacity and total phenolic content were conducted in Chemistry Laboratory, Afe Babalola University, Ado-Ekiti, Nigeria.
Methodology: Standard analytical methods were employed to determine the proximate and mineral composition of the flours obtained from four varieties of cow pea Vigna unguiculata subsp. dekindtiana, the wild relative of the cultivated subspecies; Vigna unguiculata subsp. cylindrica, cultivated, catjang; Vigna unguiculata subsp. sesquipedalis, cultivated, yardlong beans andVigna unguiculata subsp. unguiculata, cultivated, black-eyed pea. The antioxidant capacity and total phenolic content of the aqueous extracts were determined using Ferric ion Reducing Antioxidant potential (FRAP assay) and Folin-Colcalteau method respectively.
Results: The moisture content, crude fibre, ash and fat were generally low in the four varieties with significantly high protein (24.19%-25.74%). Calcium and phosphorous were found to be high in all the varieties. Antioxidant Activity ranged from 44.52-150.05 mgGAE/100g DW while the total phenolic content varied from 88.15-100.02 mgGAE/100 g DW. A linear positive relationship existed between the antioxidant activity and total phenolic content of the cow pea varieties (R2=0.3333).
Conclusion: This study shows that the four cow pea varieties could serve as good sources of protein, calcium and phosphorous with valuable antioxidant properties. All the varieties could however be utilized in food preparations and formulations for both adults and children.