Drying parameters of wild lettuce (Lactuca taraxaxifolia L) affected by different drying methods

Abstract

This study focused on the effect of drying method on drying properties of wild lettuce leaves. The fresh wild lettuce was washed thoroughly to remove extraneous parts and subjected to pretreatments by dipping 200 g of vegetable samples into the water (1.5w/v) solution with 0.3% sodium metabisulphite held at room temperature. The pre-treated and untreated leaves were weighed and loaded in stainless steel tray and subjected to drying under cabinet dryer, open-sun drying and solar dryer. The wild lettuce drying curve exhibits a gentle downward curve, i.e. a high moisture loss at the early period of drying for all the drying methods used. The effective moisture diffusivity and activation energy were determined. The effective moisture diffusivity increased with the increase in temperature of drying. This study showed that post harvest losses of wild letuce can be minimized through drying, using mechnical devices or open sun drying, which is one of the oldest preservation processes available to the mankind.