A Mathematical Model for Color Changes in Red Pepper during Far Infrared Drying

Purpose: The color changes in red pepper during far infrared drying were studied in order to establish a color change model. Methods: The far infrared drying experiments of red pepper were conducted at two temperature levels of 60, 70∘C and two air velocity levels of 0.6 and 0.8 m/s. The results were compared with the hot-air drying method. The surface color changes parameters of red pepper were measured qualitatively based on L (lightness), a (redness), b (yellowness) and total color changes ( ΔE ). The goodness of fit of model was estimated using the coefficient of determination ( R² ), the root mean square error (RMSE), the mean relative percent error (P) and the reduced chi-square ( χ² ). Results: The results show that an increase in drying temperature and air velocity resulted in a decrease in drying time, the values of L (lightness) and a (redness) decreased with drying time during far infrared drying. The developed model showed higher R² values and lower RMSE, P and χ² values. Conclusions: The model in this study could be beneficial to describe the color changes of red pepper by far infrared drying.