Improving Drying Efficiency for Red Chili Peppers Using Ventilated Solar Technology

This study compares three drying methods for Jinda red chili peppers: open sun drying (OSD), conventional solar drying (SD), and ventilated solar drying (VSD). Fresh chilies with an initial moisture content of 80% were dried to achieve the industry standard of ≤13.5% final moisture content. Temperature monitoring showed that SD reached the highest peak temperature (75°C), followed by VSD (56°C) and OSD (52°C). Significant differences in drying time were observed: VSD reached appropriate moisture levels in under 17 hours, SD in 34 hours, and OSD in 45 hours. Compared with the first day of SD and OSD, which had drying rates of 49.5% and 55.5%, respectively, VSD showed the highest drying rate, reducing the moisture content to 34.6%. By the second day, VSD had a moisture content of 12.5%, while SD and OSD retained 33.7% and 37.3%, respectively. The enhanced efficiency of VSD is attributed to the combined effects of elevated temperature and mechanical ventilation, which accelerated moisture removal despite the lower chamber temperature than in SD. While solar dryers require greater initial investment than traditional methods, they offer significant advantages in processing time, product quality, contamination prevention, and labor requirements, potentially yielding faster returns on investment. These findings suggest that VSD is optimal for commercial chili drying operations in Thailand's agricultural sector.