Nutritive and antioxidant evaluation of five leafy vegetables consumed in Western Côte d’Ivoire after refrigeration storage

Abstract

Leafy vegetables are perishable plants foods subjected to continuous changes which conduct to postharvest losses. So, there is a need to develop preservation methods in order to extent their shelf life and availability for consumers. The main objective of this study was to evaluate the impact of refrigeration storage (4°C) on the nutritive and antioxidant properties of five leafy vegetables (Abelmoschus esculentus, Celosia argentea, Ipomea batatas, Manihot esculenta and Myrianthus arboreus) consumed in Western Côte d’Ivoire. The result of the study revealed small fluctuations in the proximate composition during refrigeration storage. After 15 days of storage the contents of moisture, ash, proteins and lipids ranged within the following intervals: 66.30 - 83.04%, 5.01 – 16.95%, 8.91 – 19.66% and 0.73 – 4.01%, respectively. The residual contents of minerals at 15 days of storage were: calcium (193.34 – 639.65 mg/100g), magnesium (134.10 – 507.94 mg/100g), potassium (1245.24 – 4606.13 mg/100g), iron (35.22 – 73.30 mg/100g) and zinc (29.60 – 69.67 mg/100g). The registered losses of oxalates, phytates, carotenoids and vitamin C were estimated at 15 days of storage as follow: 8.88 – 15.19%, 23.55 – 31.10%, 8.71 - 13.49%, 19.16 – 21.33%. The total phenolic content of the refrigerated leafy vegetables initially decreased from 0 days to 5 days (164.47 – 264.64 mg/100g to 160.38 – 260.18 mg/100g) and increased (165.77 – 275.10 mg/100g) at 10 days of storage coupled with antioxidant activity retention (68.72 – 75.70%). In view to these results, it would be necessary to preserve fresh leafy vegetables by refrigeration storage within a period not exceeding 7 days in order to contribute efficiently to the nutritional requirement and to the food security of Ivorian population.