Contingency Evaluation of Performance of a Cabinet Solar Dryer Using Fresh Tomato (Lycopersicum esculentum Mill.)

Abstract

The study designed, constructed and evaluated the performance of a solar dryer using fresh tomato (Lycopersicum esculentum Mill.) in Imo State, Nigeria. The paper became necessary due to the high cost of fresh tomato fruits during scarcity (lean season) as well as the need for appropriate preservation method for tomatoes during major season to curb scarcity in the study area. Data collected were analyzed using descriptive statistical tools, proximate analyses and One Way Analysis of Variance (ANOVA). A Cabinet /flat plate solar dryer with dimensions 1.36m, 0.9m and 0.79m of length, width and height respectively was used with softwood and hardwood during construction. Saws dust was used as an insulating material, finger glass as screen, mesh screen as air inlet and outlet vent, mild steel sheet as the solar energy collector. Weight losses and temperature of the test samples were recorded at intervals during drying. The highest temperature observed in the dryer was 720C while the ambient temperature was 470C. The initial weight of the solar dried sample was reduced from 490.56g to 6.87g in 70.00 hours while sun dried sample reduced from 490.56g to 6.67g in 71.00 hours. Estimated ANOVA revealed that significant differences (P<0.05) exist between solar dried, sun dried and fresh sample (control). The carbohydrate, crude fibre, ash, protein and fat content of all the dried samples increased at 95.00% confidence level (P<0.05) respectively. The vitamins, A and E increased while vitamin C, thiamin, niacin and riboflavin decreased significantly (P<0.05). The minerals, calcium, magnesium, phosphorus, sodium, and potassium increased significantly (P<0.05). The microbial load of the sun dried sample (4.20x105cfu/g) was higher than the solar dried sample (1.22x107cfu/g). Significant difference (P<0.05) also exist in the sensory evaluation of the appearance/colour, aroma, texture and general acceptability on the sun dried, solar dried and fresh tomato samples. Finding showed that solar drying is efficient, effective and most hygienic method. It was therefore recommended that a storage test be carried out on dried samples and also more durable glass should be used for the design and construction of a solar dryer for improved efficiency and performance. Government at all levels should intensify effort on the need for solar drying of fresh tomato samples as well as provision of fabrication materials/equipment for solar dryers as this would positively enhance the availability of fresh tomato fruit all year in the area and beyond.

Keywords: Fresh Tomatoes, Cabinet solar dryer, Design, Construction, Performance, Microbial, Mineral, Vitamins and Organoleptic Properties, ANOVA