CATALYTIC INFRARED AND HOT AIR DEHYDRATION OF CARROT SLICES

This study investigated the drying and quality characteristics of carrot slices under catalytic infrared (CIR) and hot air (HA) heating. Carrot slices with thicknesses of 3, 5 and 7mm were dried at temperatures of 60, 70 and 80C with both methods. CIR had higher drying rates, shorter drying times and greater effective diffusivities than HA before the moisture contents reached the range of 16-30% on a wet basis (w.b.). The total drying times required by CIR to reach the final moisture content was 60% less than HA. The effective diffusivities were in the range of 2.38-10.30x10(-9)m(2)s(-1) for CIR drying and 1.43-5.50x10(-9)m(2)s(-1) for HA drying. Results revealed that carrot slices dried with CIR, particularly at 60 and 70C, had better rehydration characteristics than the samples dried with HA. Thickness had a significant impact on overall color change of carrot slices. The obtained correlation coefficient (R-2) and root mean square error values indicated that the Midilli model was the best for predicting the moisture ratio change kinetics of carrot slices for both drying processes. Practical ApplicationsThese results indicate that CIR drying is an effective method to obtain high-quality products. This paper was to optimize the CIR and HA process of carrot slices. The significance of this research can improve the drying efficiency of CIR in carrot slices. Throughout the trial, the production-scale CIR dryer was used, which means that the CIR process can provide technological support to produce dried carrot slices. In addition, it also provides a reference using sequential CIR drying and HA drying for carrot slices.