Solar Dryer for Drying Cabbage in Single and Multilayers

Solar drying is an easy and environmentally friendly way of food preservation. The use of a solar dryer for multicrop may also make this technology cost-effective. In fact, the performance evaluation of a solar dryer for different fruits and vegetables promotes the usability of a dryer for crops. Hence, in this study, a newly developed natural convection solar dryer has been evaluated for drying cabbage. Cabbage samples were pretreated with a brine solution (with 5% [w/w] NaCl) followed by blanching. Pretreated samples were dried both in the dryer and open sun. Control samples were also dried in the solar dryer and open sun. The cabbage was dried in single and multilayer arrangements, maintaining thin layer drying thickness. Temperature distribution in and outside of the dryer was also investigated during the experiment, both spatially and temporally. The acceptability of dried cabbage was checked using a 9-point hedonic scale test. The experimental value of the moisture ratio was fitted with four different thin layer drying models—Newton, Page, modified Page, and Henderson. The drying air temperature consistently exceeded the ambient temperature by approximately 1°C–35°C, depending on the intensity of solar radiation. Drying efficiency for single-layer and multilayer arrangements were 25.25% and 43.57%, respectively. Hence, multilayer drying of cabbage in the dryer can be an effective means of drying with higher efficiency. From the acceptability test, it was found that solar dried pretreated cabbage was mostly liked. The best fitted model was the Page model for both single and multilayer drying. Performance evaluation for multilayer drying of other fruits and vegetables might increase this dryer’s usability.