Effect of Solar and Open Sun Drying on the Microbial Loads and some Nutrients of Tomato

Abstract

Farmers in Nigeria still preserve tomato by traditional open sun drying with its inherent problems. In a way to combat this short fall, simple inexpensive passive solar dryer for sliced tomato was constructed, tested and the qualities of the dried tomato samples analyzed. ANOVA of tomato samples dried with the solar dryer indicated that there were no  significant difference (P<0.01) between the fresh tomato samples and the tomato samples dried with the solar dryer when the Protein content, total fungi count, total bacterial count, vitamin C content and the colour qualities  were considered. On the other hand, the fresh tomato samples and the tomato samples dried in open sun exhibited highly significant difference. The solar dryer achieved 64.5 % savings in drying time when compared with the open sun drying method. The solar dryer took a total of 54 hours to dry the sliced samples of tomato, while the open sun took a total of 152 hours to dry the sample to self-storage moisture content level. The sliced tomato samples in the solar dryer and open sun dried from initial moisture content (M.C.) of 94% wet basis to final M.C. of 5 % wet basis. Genstat statistical software and Microsoft excels packages  were used and the analysis of the performance of solar dryer and open sun drying methods showed that the solar dryer achieved 27.14 % drying efficiency while the open sun indicated 2.02 % drying efficiency. Also the solar dryer raised the ambient temperature on the average from 30.6 ^oC to 46.5 ^oC.