Effect of processing methods on the nutritional quality of Solanum aethiopicum and Colocasia esculenta leafy vegetables commonly consumed in Ebonyi State, Nigeria

Abstract

Background: Green leafy vegetables provide many health and nutritional benefits to mankind. Processing to prolong the shelf-life of vegetables goes through several stages, though it might affect the nutrient composition.
 Objective: This study evaluated the effect of the processing method on the nutrient, anti-nutrient, and phytochemical composition of commonly consumed green leafy vegetables in Ebonyi state, Nigeria.
 Methodology: The study adopted an experimental design. Three hundred grams (300 g) of each of the leafy vegetables (Solanum aethiopicum and Colocasia esculenta) were cleaned, washed, and divided into three equal portions (100 g, each). One portion each was retained raw (served as a control); the others were processed by steaming and shade-drying methods and were later analyzed in the laboratory for nutritional, anti-nutrient, and phytochemical content using standard methods. One-way analysis of variance was used to compare the data obtained. P < 0.05 was considered significant.
 Result: The steamed samples had higher moisture content than a shade-dried sample. Similarly, steamed Colocasia esculenta had the highest vitamin C among the processed leaf samples. Also, steamed Solanum aethiopicum had the highest value of vitamin E when compared to other processed samples. Shade-dried samples of Solanum aethiopicum had higher values of mineral content than its steamed counterpart while steamed Colocasia esculenta had higher potassium/magnesium content and lesser sodium/phosphorus than shade-dried Colocasia esculenta leaf. Steamed leaf samples had higher carotenoids and flavonoids with lesser alkaloid levels than shade-dried samples. Steamed Colocasia esculenta leaf had higher saponin and oxalate content than shade-dried Colocasia esculenta leaf, while shade-dried Solanum aethiopicum leaf had higher oxalate, phytate, and saponin level than the steamed Solanum aethiopicum.
 Conclusion: The study showed that leafy vegetables contain appreciable levels of nutrients and the different processing methods either increased or reduced the nutrient present in the leaves.