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Comparing Quality Characteristics of Oven‐Dried and Refractance Window‐Dried Kiwifruits

Jafari, Seid‐Mahdi, Azizi, Dariush, Mirzaei, Habibollah, Dehnad, Danial
Journal of food processing and preservation 2016 v.40 no.3 pp. 362-372
color, drying, energy, hardness, kiwifruit, rehydration, sensory properties, temperature, water content
Our aim was to evaluate the qualitative properties of kiwifruits produced by refractance window (RW) as a novel drying method. The effects of slice thicknesses (0.8, 1.6 and 2.4 mm) and drying temperatures (80, 90 and 100C) on drying duration as well as qualitative parameters of dried samples including textural hardness, color, rehydration index and organoleptic properties were investigated. The required time to reach the final moisture content was considerably lower in RW method compared with oven drying, which was maximally 140 min lower for slice thickness of 2.4 mm at 100C. Generally, ΔE values and rehydration ratios of oven‐dried kiwifruits were higher and lower than RW‐dried samples, respectively. The average scores given to each sensory property of oven‐dried samples were between 1 and 3, whereas they were in the range of 4–5 for RW‐dried kiwifruits, exhibiting more satisfactory situations for the latter samples. PRACTICAL APPLICATIONS: It is necessary to develop alternative drying methods that could guarantee quality retention and maximize financial productivity during the drying process. Refractance window is a novel drying technique utilizing circulating hot water to transfer thermal energy to a thinly spread liquid material placed on a conveyor belt. In this work, we have successfully utilized this technique for drying kiwifruits, and the results have been compared with conventional oven drying for the first time.