Investigation and Comparative Study of Two Methods of Solar Dryer and Sun Drying for Drying Tomato Slices

Abstract

This study applied a novel direct solar dryer method for tomato slices, using a box-shaped dryer with three trays, a transparent glass cover as a solar collector, and a blower. The performance and product quality of the solar dryer and sun drying methods were compared. Tomato slices underwent sorting, bleaching, drying, and packaging, becoming ready for commercialization. The tomato slices dried until the final moisture content reached 25–50% (w.b) from an initial moisture content of 90% (w.b). The solar dryer achieved the highest average drying rate of 0.644 g/min on the first tray and a drying efficiency of 25.09%, with total energy consumption of 193.85 kJ/kg and 0.0111 kg/kJ for specific energy consumption (SEC) and specific moisture extraction rate (SMER), respectively. Quality assessments included color, texture, vitamin C content, and SEM testing. Dried tomato slices turned significantly browner compared to fresh ones, had different texture attributes from sun-drying-dried slices, experienced vitamin C degradation due to high temperatures, and showed brittle walls due to moisture loss, as indicated by SEM testing.