Effect of Drying Methods on the Nutrient and Phytochemical Properties of Some Cultivated and Wild Leafy Vegetables.

Abstract:

The aim of this study was to determine the nutrient and phytochemical composition of fresh, sun and shade dried okra, bitter, scent, G. latifolium and roselle leaves. The vegetables were purchased from two markets. Okra, bitter, scent and G.latifolium leaves were purchased from Nsukka and roselle leaves were bought from Jos market. All the vegetables were washed, weighed and divided into two equal parts. Each part was sun, or shade dried, pulverized, packed and stored. The fresh samples for each of the vegetables served as control. The fresh, sun and shade dried samples of all the vegetables were separately analyzed for various nutrient and phytochemicals on dry weight basis using standard assay techniques. Data generated were statistically analyzed. The means were separated and compared. All the fresh samples had high moisture values(Okra leaf; 62.22%, bitter leaf; 62.32%, scent leaf; 62.46%, G.latifolium; 61.44% and roselle leaf; 85.53%) . The moisture content of the sun and the shade dried samples differed (P<0.05). The exception was that of roselle whose sun and shade dried values were comparable (6.36 and 6.38%) (P>0.05). Fresh samples of all the vegetables had lower protein. The processed okra, bitter, scent and roselle leaves had comparable values (P>0.05). Moisture lost due to drying increased nutrient density of the vegetables, especially the roselle leaves. The phytochemicals (Tannins, phytate, saponins and flavonoid) of the fresh samples were higher than those of the sun and the shade dried samples. This showed that fresh vegetables are better sources of phytochemicals as against the sun and the shade dried samples. The shade dried samples had lower tannins except for the bitter leaf and the sundried samples had lower phytate except the G. latifolium. The sun and the shade dried samples had comparable saponins and flavonoids content (P<0.05). As judged by the results, domestic food processing techniques improved the nutrient content of these vegetables and decreased some of the food toxicants and antinutrients.