Antioxidants and Nutrients Composition in Selected Cultivated African Vegetables and Herb: the Impact of Maturity and Drying

Abstract

Ocimum gratissimum, Phyllanthus amarus and Lactuca taraxacifolia are good sources of phytochemicals and they have gained attention for their potential to provide natural remedies for various ailments. This study was carried out to evaluate the effect of maturity stages and drying methods (oven drying (50oC) and air drying at room temperature (28-32oC) on the antioxidative properties, vitamins and mineral contents of three cultivated plants. The plantas were harvested at two different stages of maturity and subjected to two different drying methods. The antioxidants of the plants ranged from 25.21-70.94 % (Reducing power (DPPH)), 0.57-0.73 mg/g (Total antioxidants contents (TAC)), 0.55- 4.66 mg/g (Total flavonoids contents (TFC)), 0.03-0.72mg/g (Free radicals scavenging ability (FRAP)) and 0.18-0.39 (Total phenolic content(TPC)).The vitamin composition varied from 2.45-3.41 mg/g (vitamin C), 0.01-0.35 mg/g (vitamin D), 0.13-0.14 mg/g (vitamins B1), while its mineral compositions ranged from 278.41-1360.66 mg/100g (K), 222.73-1088.53mg/100g (Ca), 213.27-612.08mg/100g (Mg). The PCA biplot revealed a data variance of about 69.42% and the preference for the samples A1O C1O (Ocimum gratissimum at young age oven dried at 50 oC) and C1O (Phyllatus amarus at young age oven dried at 500C) might be attributed to their high antioxidant capacities retention, while sample B1N (Lactuca taraxacifolia air dried at young age) might also be considered because of its richness in vitamin B1, vitamin C and FRAP.