| Summary: | The objective of this work was to study the influence of the drying temperature, infrared (IR) radiation assistance, and the Mylar™ film thickness during <i>Physalis</i> fruit purée drying by the Refractance Window™ (RW™) method. For this, a RW™ dryer layout with a regulated bath at working temperatures of 60, 75, and 90 °C, Mylar™ thicknesses of 0.19, 0.25, 0.30 mm and IR radiation of 250 W for assisting RW™ drying process was used. Experimental curves data were expressed in moisture ratio (MR) in order to obtain moisture effective diffusivities (non-assisted RW™: <i>D<sub>eff</sub></i> = 2.7−10.1 × 10<sup>−10</sup> m<sup>2</sup>/s and IR-assisted RW™: <i>D<sub>eff</sub></i> = 4.2−13.4 × 10<sup>−10</sup> m<sup>2</sup>/s) and further drying curves modeling (Page, Henderson−Pabis, Modified Henderson−Pabis, Two-Term, and Midilli−Kucuk models). The Midilli−Kucuk model obtained the best-fit quality on experimental curves regarding statistical tests applied (Coefficient of Determination (<i>R</i><sup>2</sup>), <i>Chi-Square (χ</i><sup>2</sup>) and Root Mean Square Error (<i>RMSE</i>). Microscopical observations were carried out to study the RW™ drying conditions effect on microstructural changes of <i>Physalis</i> fruit purée. The main findings of this work indicated that the use of IR-assisted RW™ drying effectively accelerates the drying process, which achieved a decrease drying time around 60%. Thus, this combined RW™ process is strongly influenced by the working temperature and IR-power applied, and slightly by Mylar™ thickness.
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