Mathematical modeling of hot air drying kinetics of Momordica charantia slices and its color change

Abstract

This study presented the drying characteristics of fresh Momordica charantia slices at different drying temperatures (50, 60, 70 and 80°C) and different thicknesses (0.5, 0.75 and 1.0 cm). Three mathematical models including Page, Henderson and Pabis and Wang and Singh equations were compared and discussed. The results showed that the Page model provided the best correlation capacity with the decision coefficient R2 of 0.998. The color change of Momordica charantia slices during hot air drying at different temperatures were also studied by the measuring of color parameters such as the values of Hunter L* (whiteness/darkness), a* (redness/greenness) and b* (yellowness/blueness). The total color change (ΔE) of the samples was observed to increase as drying temperature increased. The results show that the color of Momordica charantia slices changed sharply when temperature was higher than about 70°C. The study could provide theoretical bases of the equipment design and process optimization for hot air drying of Momordica charantia.