Effects of Three Drying Techniques on Mineral Composition of Some Leafy Garden Vegetables

Abstract

The effect of three different drying techniques (Sun drying at ambient temperature for 4 days, oven drying at 150 o C for 4 hours, and drying with electrical moisture analyzer stabilized at 70 o C for 1 day) on the mineral composition (i.e. Ca, K, Mg, Na, and P) of three different green leafy vegetables (Moringa oleifera, Spinacea oleraceae and Vernonia amygdalina) were studied. The results obtained showed that the different types of vegetables had an appreciable amount of minerals, though with varying concentration. The Spinach, Spinacea oleraceae samples' ability to retain the studied nutrients was much favored by sun drying technique. Its content for P, K, Na, Ca and Mg (4.47 mg/kg, 18.41 mg/100g, 21.00 mg/100g, 0.19%, 0.35%) are probably the best result for it. As for the Drumstick, Moringa oleifera, its ability to retain the investigated nutrients is enhanced by the moisture analyzer drying method. Its content for P, K, Na, Ca and Mg (4.03 mg/kg, 7.83 mg/100g, 20.33 mg/100g, 0.11%, 0.16%) are likely the best for it. The Bitter leaf, Vernonia amygdalina seems to be much favored, in its nutrients retention ability by using oven drying. This could be seen from the content of P, K, Na, Ca and Mg (4.04 mg/kg, 20.58 mg/100g, 12.08 mg/100g, 0.07%, 0.14%) obtained. However, no definite conclusion could be drawn as which method is the best for each of the investigated vegetables in relation to all the studied elements.