Document Type : Research Paper
Authors
1 Postdoctoral researcher of the Iran National Science Foundation (INSF)
2 Associate Professor Department of Agricultural Engineering Institute, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Address: P.O.Box 91735-488, Mashhad-Iran http://kanrrc.areo.ir Tel&Fax(work)
3 Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
4 Department of Agricultural Machinery, Science and Research branch, Islamic Azad University, Tehran.
Abstract
Drying by the refractance window is one of the new drying methods that has attracted a lot of attention in recent years due to its many advantages and the use of infrared in these dryers leads to the drying of heat-sensitive products such as plums with better quality in a shorter time. In this paper, three drying methods including: Refractance Window Dryer (RWD), Infrared-Assisted Refractance Window (IFRWD) and Hot Air thin layer dryer (HAD) was used to investigate the drying kinetics of plum puree with a thickness of 5 mm at a temperature of 70°C. The drying times for IFRWD, HAD, and RWD were 210, 275, and 390 minutes, respectively. Using IFRWD reduced the drying time by 46% and 24% compared to HAD and RWD. Eight thin-layer drying models available in the literature were fitted to the experimental data, among which the Midilli model was the best fit. The maximum effective diffusion coefficient (1.824 × 10⁻⁸) and rehydration ratio (3.24) were observed in IFRWD, whereas the minimum values (1.841 × 10⁻⁸ and 2.64, respectively) were recorded in HAD. The results indicated that the IFRWD provided the most efficient drying conditions; thus, this method is recommended for drying plum puree at 70 °C with a layer thickness of 5 mm.
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