Vitamins and phytochemical contents in four leafy vegetables subjected to different processing methods

Abstract

Vitamin and phytochemical contents of the leaves of Vernonia amygdalina, Gnetum africanum, Gongronema latifolium and Ocimum gratissimum subjected to different processing methods were investigated. Processing treatments employed include fresh milling, sun drying, oven drying, steaming and a combination of these. The vitamins evaluated include vitamins A, B₁, B₂, B₃, B₆ and E while the phytochemicals were alkaloids, saponins, tannins, phenols, hydrocyanic acid and phytic acid. The results indicated high levels of vitamins and phytochemicals in the leaves. The different processing methods produced diverse effects on the vitamin and phytochemical contents of the leaves. In all the vegetables tested, fresh milling followed by sun drying were the most effective methods of retaining vitamins and phytochemicals, while steaming in combination with oven drying reduced most of the vitamins and phytochemicals. Other treatments caused varying degrees of significant losses of vitamins and phytochemicals at P = 0.05 in all the vegetables tested. To ensure safety and wholesomeness in the use of these leaves, processing methods leading to the retention of maximum nutrients and loss of maximum anti-nutrients should be encouraged to achieve the desired objective.

Keywords: Vernonia amygdalina, Gnetum africanum, Gongronema latifolium, Ocimun gratissimum, processing, vitamins, phytochemicals

African Journal of Biotechnology Vol. 12(26), pp. 4168-4173