Nutritive and Antioxidant Characteristics of Roasted Leafy Vegetables Consumed in Western C?te d’Ivoire (Ivory Coast)

Abstract

African Leafy Vegetables (ALVs) have long been recognized as the cheapest and the most abundant potential sources of vitamins and minerals using for fighting against malnutrition. Five leafy vegetables (Abelmoschus esculentus, Celosia argentea, Ipomea batatas, Manihot esculenta and Myrianthus arboreus) that are used for sauce preparation in Western Côte d’Ivoire (Ivory Coast) were subjected to roasting in order to evaluate the effect of this non conventional processing method on their nutritive and antioxidant properties. This study showed that longer time (higher than 2 min) of roasting at 180-200°C caused negative impact with nutrient losses but positive impact by reducing anti-nutrients such as oxalates and phytates. The registered losses at 2 min of roasting were as follow: ash (7.47 – 36.65 %), proteins (3.04 – 32.66%), vitamin C (75 – 92.14%), carotenoids (27.34 – 81.94%), oxalates (3.84 – 10.89%) and phytates (0.45 – 15.72%). Roasting processing of the studied leafy vegetables highlighted a significant increase (2.63 to 13.83%) of polyphenols contents coupled with increasing of antioxidant activity. Moreover, after 2 min of roasting processing, the residual contents of minerals were: calcium (202.45 – 542.06 mg/100g), magnesium (123.73 – 467.43 mg/100g), potassium (1209.85 – 3796.16 mg/100g), iron (44.72 – 128.47 mg/100g) and zinc (6.35 – 40.13 mg/100g). All these results suggest that roasting processing (less than 2 min at 200°C) may be used as valuable cooking method of leafy vegetables in order to minimize nutrient losses and to contribute efficiently to the food security of Ivorian population.