Design, Fabrication and Performance Evaluation of a Charcoal-Fired Tomato Dehydrator for Developing Countries

Abstract

For the purpose of enhancing the food security and economies of developing countries, thereby meeting the sustainable development goals (SDGs 2030) especially SDG No. 2, which is concerned with hunger alleviation, achieving food security, improving nutrition and promoting sustainable agriculture before the year 2030, an energy-efficient charcoal-fired tomatoes dehydrator having an efficiency of 88.6% and a drying rate of 0.51 kg/hour has been designed, fabricated and tested. It basically comprises of a combustion unit (CU) for heat energy generation through the combustion of charcoal, a heat exchanger unit (HEU) comprising of fins for efficient transfer of the generated heat through a 240 V 0.15 HP DC centrifugal fan and a drying unit (DU). The results of its performance evaluation showed that, with a safe drying air temperature of 50 oC at 6 m/s fan speed, the dehydrator is capable of drying 5 kg of tomatoes per batch from an initial moisture content of 94% to 22% with a final weight of 1.4 kg over a drying period of about 7 hours. The microbiological analysis conducted on the post-drying tomato sample revealed a total bacterial counts (TBC) of 1.61 x 102 cfu/g and a total fungi counts (TFC) of 0.27 x 102 cfu/g which are both far below the allowable limits (103 cfu/g) for human consumption. The dehydrator has proved effective for extending the shelf life of tomatoes by mitigating the rate of spoilage due to microbial activities through drying, thereby enhancing the food security and economy of developing countries.