DEVELOPEMENT OF A VEGETABLE DRYER

A Vegetable dryer of dimension 1.50 m (high) x0.72 m (wide) x 0.59 m (breadth) was developed using mildsteel iron and its performance evaluated. The deviceconsists of a drying chamber with three drying trays; fansincorporated for heat circulation, a heating element of2000 W, four swivel caster rollers for ease of mobility, athermostat to regulate the heat generated in the dryingchamber and a thermo-gauge inserted to monitor thetemperature in the drying chamber. The vegetable dryerhas a drying capacity of 34 kg and three compartments of0.25 m equal spacing. The dryer is partitioned at 0.75 m,0.1 m and 1.25 m from the heating element, with the first(bottom) tray, the second tray (middle) and the third(upper) respectively. The device performance wasevaluated under no-load and load conditions at 50 °C, 60°C, and 80 °C temperatures with three replications.Results obtained under no-load indicated thattemperatures very close to the preset values (by thethermostat) were attained within 5 mins. Under loadcondition, the dryer was evaluated by drying 16.74 kg oftomatoe slices at 50 °C, 60 °C, and 80 °C. Weight reduction(degree of moisture loss) from the slices was recorded atintervals of 1hour until a nearly constant weight wasobtained. The result revealed that the dryer has a meandrying efficiency of 80.6 % and drying rate of 0.02 kg/hr.At a drying time of 10 hours and temperatures of 50 °Cand 60 °C, 16.74 kg of tomatoes were reduced to 1.23 kgand 1.13 kg representing 93 % (wb) of removed moisture,while a final weight of 1.08 kg dry matter was obtainedfrom the same starting weight of wet tomatoes at 80 °Crepresenting 94 % (wb) of moisture loss for the samedrying time. ANOVA studies indicated that the effect oftemperature and tray level on drying of vegetable(tomatoes) were highly significance at (P< 5 %). The driedvegetable (tomatoes) is free from dust and any form ofcontamination making it healthy for consumption.