Effect of pre-treatment and preservation methods on the nutritional quality of bitter gourd leaves from two different sources

Abstract

The effects of pre-treatment and preservation methods on the mineral composition and nutritional quality of bitter gourd leaves harvested from the wild and around homestead were investigated. The pre-treatments consisted of 30 sec, 2 and 5 min immersion of leaves in boiling water followed by one of oven, sun or air-drying as preservation methods. Dried materials were subsequently milled and analyzed for mineral and nutritional values. Results revealed that the fat contents in both the samples were low and comparable. The mean fibre content in leaf samples from the wild was 11.63±2.11%, while that from the homestead was 8.81±1.64%. Elevated levels of protein content were obtained from both the sources; being significantly higher in the wild (29.01±3.81%) than from the homestead (24.73±1.84%) samples. The mineral composition of the samples showed highly marked variation across the different pre-treatment methods; with elevated level of iron and zinc. Immersion of leaf samples in boiling water for 30 sec, followed by oven drying as a preservation method resulted in a marginal increase in the mineral composition. These results underpin the relevance of indigenous knowledge practices by rural dwellers in the preservation of inherent nutritional values of important traditional vegetables for improved nutrition. There is an urgent need to ensure the conservation of this important indigenous vegetable crop through promoting increase cultivation at the level of small-scale farmers as a priority medicinal plant for nutritional security, income generation and the prevention of its extinction.