Development of an automatic chili drying controller based on computer vision

Color of dried chilies is one of the most key factors that influences consumers’ preference. It is mainly affected by the drying process. Traditionally, drying temperature is fixed during the drying process without regard to the quality of chilies being dried. Thus, the aim of this research is to develop a controller for the chili drying process that determines the drying temperature according to the change of chili color. To measure the chili color, we built a hot air tray dryer incorporated with a computer vision system which measures the chili color during drying. We converted the RGB color model to the L*a*b* color model and calculated the change of the a* component (\delta a). If \delta a within 15 minutes was less than 2, then, the drying temperature was set to 90°C for ten minutes and set back to 80°C, otherwise, it was set to 80°C. The experimental results showed that the drying time was shortened, compared to the 80°C drying temperature. The color of dried chilies was improved, compared to the 90°C drying temperature