Effect of refrigeration storage on nutritive and antioxidant properties of five leafy vegetables consumed in southern Côte D’Ivoire

Abstract

Leafy vegetables are highly perishable food items and require special processing treatment to prevent postharvest losses. This study was designed to evaluate the effect of refrigeration storage on the nutrient and antioxidant properties of five leafy vegetables (Colocacia esculenta, Basella alba, Solanum melongena, Talinum triangulare and Corchorus olitorius) commonly used in Southern Côte d’Ivoire. These leafy vegetables were refrigerated for 5, 10 and 15 days at 4°C. Ash, fibre, protein and carbohydrate contents and calorific values varied after 5 days of storage as follow: 7.19±0.28 to 19.16±0.6%, 11.64±0.14 to 24.24±0.12%, 8.05±0.41 to 20.31±1.54%, 47.05±0.49 to 57.86±0.53% and 240.32±6.11 to 286.03±5.68 kcal/100 g, respectively. During 5-days cold storage, the results revealed losses in anti-nutrients factors (oxalates and phytates) ranged from 84.67-742.33 and 15.15-33.27 mg/100 g for oxalates and phytates, respectively. Residual mineral contents after 5 days of refrigeration were: calcium (366.76-705.85 mg/100 g), magnesium (165.96-730.95 mg/100 g), phosphorus (214.45-752.76 mg/100 g), potassium (1046.43-2178.04 mg/100 g), iron (50.16-101.97 mg/100 g), sodium (25.31-368.03 mg/100 g) and zinc (12.43-59.09 mg/100 g). Vitamin C, carotenoid and polyphenols slightly decreased during refrigeration storage. These losses could be attributed to the respiration, transpiration, ethylene production and enzyme activity during storage. The present work showed that refrigeration processing (less than 5 days at 4°C) of leafy vegetables could be the best time of preserving their nutritive value and antioxidant properties.