EFFECT OF DIFFERENT DRYING METHODS ON THE ANTIOXIDANT PROPERTIES OF 4 LEAFY VEGETABLES CONSUMED IN NORTHERN CÔTE D'IVOIRE

Coulibaly Tialafolo Alassane, Méité Souleymane*, Touré Abdoulaye, Zoro Armel Fabrice, Kablan Ahmont Landry Claude, Coulibaly Adama and Djaman Allico Joseph

ABSTRACT

In tropical Africa, reports of the antioxidant potential of consumed leafy vegetables are rare. In order to contribute to their valorization, leafy vegetables consumed in the north of Côte d'Ivoire (Cerathoteca sesamoïdes, Leptadenia hastata, Ocimum gratissimum and Portulaca oleracea) were studied. The objective of this study was to evaluate the effect of three drying treatments (sun, oven and shade) on the antioxidant properties of these leafy vegetables. These leafy vegetables were collected in the cities of Korhogo and Dabakala located in the North and North-central of Côte d'Ivoire, respectively and then were subjected to different drying methods, namely shade, sun and oven before their antioxidant properties were determined. The results show that shade drying resulted in less loss of vitamin C (37 to 66%) and carotenoids (93 to 100%). Leaves of L. hastata have the residual vitamin C (23.96±0.28 mg/100g) and carotenoids (0.32 ± 0.01 mg/100g) levels. This drying also resulted in a better concentration of phytochemicals. Leaves of O. gratissimum recorded the highest contents of total polyphenols (1118.19±0.74 mg/100g) and tannins (69.75 ± 0.43 mg/100g) while the leaves of C. sesamoïdes have the highest flavonoid content (99.44 ± 0.28 mg/100g). The concentration of phenolic compounds increases an antioxidant activity in three drying modes. This increase is greater during shade drying. O. gratissimum has the highest antioxidant activity (86.78%) during shade drying. Based on their antioxidant properties, L. hastata and O. gratissimum leaves could be considered good ingredients in the formulation of dietary supplements.

Keywords: Leafy vegetables, antioxidant activity, sun drying, shade drying, oven drying.