ABSTRACT

Two identical passive cabinet solar dryer of 50kg capacity each were designed and fabricated (one with regulator and other without regulator at the vents). One of the dryers was constructed with air inlet and outlet regulator automatically controlled by sensitive sensors primed by solar cell while the other dryer was constructed without air inlet and outlet regulator automatically controlled. The sides and top cover of the dryers were made of 3mm thickness perspex glass and other available materials. Fresh firm and ripen Roma-VF tomato and unripe Musa Cardaba cooking banana variety sliced into 15mm thickness were dried with the dryers and open sun as control under the same environmental conditions which the drying products are exposed to. Moisture content of 90.2 % for tomato and 83.3% for cooking banana respectively were used for the performance evaluation of the developed solar dryers. The results was subjected to statistical analysis showing that, it took three (3) days to dry the products using dryer with controlled vents and six (6) days for open sun drying to a safe moisture content of 4% for tomato and 6% for cooking banana respectively. The rapid rate of drying in the dryer reveals its ability to dry food items reasonably rapidly to safe moisture. The drying efficiency of the dryer was 31%, 21% and 15% for dryer with regulator, dryer without regulator and open sun drying respectively, with drying rate of 0.62kg/hr,0.57kg/hr and 0.3125kg/hr respectively. The tomato and cooking banana samples dried with the dryers are found to be of high quality in appearance and acceptable for human consumption as well free from contaminations than the open sun drying which took an average of 144 hours and 132 hours for drying tomato and cooking banana respectively. The samples were subjected to Micro-biological and organoleptic test showing that tomato and cooking banana dried with solar dryer with regulator and solar dryer without regulator was within the safe storage moisture content suitable where the microbial activities are inactive while the one of open sun xv drying was not within the safe storage moisture content suitable where the microbial activities are inactive.