Nutritional and Antioxidant Characterization of Blanched Leafy Vegetables Consumed in Southern Côte d’Ivoire (Ivory Coast)

Abstract

The effect of blanching on the proximate composition, nutritive value and antioxidant properties of five leafy vegetable species (Basella alba, Colocasia esculenta, Corchorus olitorius, Solanum melongena and Talinum triangulare) used in the preparation of Ivorian diets was investigated. These leafy vegetables were subjected to steam blanching in a pressure cooker for 15, 25 and 45 min. This study highlighted losses (P < 0.05) of nutrients and anti-nutrients components at 15 min of blanching as follow: ash (6.68 – 33.80 %), proteins (0.56 - 15.71 %), vitamin C (4.75 – 73.21 %), carotenoids (18.77 - 72.76%) oxalates (2.16 – 42.62 %) and phytates (20.32 – 71.56 %). Contrary to the registered losses, the average increases of polyphenols and crude fibres contents at 15 min of blanching were 1.51 to 5.19% and 0.62 to 8.87%, respectively. Furthermore after 15 min of blanching time, the residual contents (P < 0.05) of minerals were: calcium (214.71 – 608.95 mg/100 g), magnesium (85.50 – 435 mg/100 g), potassium (1243.32 – 2940.38 mg/100 g), iron (17.07 – 45.86 mg/100 g) and zinc (17.48 – 64.03 mg/100 g). All the results above showed that blanching processing reduces nutritive value of leafy vegetables consumed in Southern Côte d’Ivoire. In order to contribute efficiently to the nutritional requirement and to the food security of Ivorian population, the domestic blanching time must be less than 15 min for preserving the beneficial nutritive properties of the studied leafy vegetables.