Antioxidant and polyphenol indices of popularly consumed indigenous soups in Delta State, Nigeria

Abstract

There is little knowledge on the polyphenol content of indigenous soups commonly consumed in Africa. This study assessed the polyphenols and antioxidant properties (in-vitro) of popularly consumed traditional African soups in Delta State, Nigeria. Preliminary survey was conducted in four towns of four selected Local Government Areas on the type of food they eat. Four soups (pepper soup ‘Offe ikere’ from Umutu town, okra pepper soup ‘Igbabga ofofo’ from Egbokodo town, banga soup ‘Oghwo ameidi’ from Ekeranvwe town and red palm oil soup ‘Abaikpo’ from Bomadi town) were chosen for the study based on three days 24 h dietary recall and the frequency of consumption. The soup samples were prepared according to the discretion of respondents in various towns. Analyses were carried out using standard methods. Polyphenols were analysed using high performance liquid chromatography (HPLC). Alkaloids, saponins, phenols, flavonoids, tannins, steroids and carbohydrate were present in all the soups samples. Igbagba ofofo was significantly (p < 0.05) higher in total phenolic content, flavonoids, vitamin E, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP), and total antioxidant capacity (TAC) when compared to Abaikpo, Oghwo amiedi and Offe ikere at varied concentrations. Polyphenols such as quercitin, chlorogenic acid, kaempferol, ellagic acid, capaene, skimmianine, inulin, butyrolactone, catechin, naringerin, glycyrrhizin, capsaicin, glycerretol, cinnamic acid, humulene, estragol and citral were found in the soups. In conclusion, the spices used in preparation of the soups could have yielded the polyphenols and antioxidant potential that enriches them. However, in these efficacies, Igbagba ofofo had higher polyphenols and antioxidant properties in relation to Oghwo amiedi, Offe ikere and Abiakpo soups. The preparation of indigenous soups in rural areas should be encouraged, since they contain high values of polyphenols and antioxidant nutrients.