Antioxidants Characteristics of Traditional Cultivars of Rainfed rice (oryza glaberrima) from Goh-Djiboua and Mountains Districts in Côte D’ivoire

Abstract

The antioxidant compounds in foodstuffs are of great interests for the nutritional and health safety of consumers, given the preponderant role of food in the overall health. The current work focusses the main antioxidant compounds and activities from 27 traditional varieties of rainfed rice. Qualitative tests were performed to check the presence of the antioxidant compounds, namely total polyphenols, flavonoids, tannins, alkaloids, saponins, sterols and terpenes, probed and measured from raw brown rice or whole grains using standard methods. In addition, the antioxidant activity was investigated using standard ABTS and DPPH methods. Only total polyphenols and, to a lesser degree, flavonoids, were qualitatively found from the studied rice samples. The total polyphenols contents (43.83 to 194.60 mg GAE/100g) and flavonoids contents (16.08 to 124.83 mg QE/100g) displayed significant differences from the traditional rainfed rice cultivars investigated (P<0.05), recording higher values in the grains of coloured pericarp rice compared to the other varieties. The greatest ABTS content is found in the varieties Sipricri (357.51 µM Trolox Eq/g) and Jbröko (137.85 µM Trolox Eq/g) which respective percentages of degradation of ABTS radicals are 52.95% and 20.09%. Regarding DPPH assay, the lowest EC50 is found from the variety Sipricri (36.07 µM Trolox Eq/g) and the highest with the rice Glawlon (3445.84 µM Trolox Eq/g). The antioxidant trend of the rainfed rice is nutritionally favorable to support a safety food diet using rice as common local food stuff for populations.