Determination of thin layer drying characteristics and sorption properties of kiwi fruit

Drying process is one of the methods used to supply consuming of fruits and vegetables out of the harvesting period and to preserve the market value. In this research, kiwi fruit, which is rapidly growing of its production in our country in recent years, was sliced in 3 mm thickness and dried at different temperatures (50-60-70 °C) and constant airspeed (2.2 m s-1) in a hot air dryer as thin layer. The sorption isotherms, which are very important in terms of continuity of product quality stability and which are used to understand the physicochemical relationship between water and product, were determined at 3 different temperatures (30, 40 and 50 °C) and 5 different ambient relative humidity conditions for fresh and dried kiwi samples. The obtained experimental sorption data were adapted to 4 different models, namely BET, GAB, Oswin and Smith models. Four mathematical drying models namely Henderson and Pabis, Page, Logarithmic, Wangh and Singh were applied to the experimental results of drying processes. It was determined that the most suitable mathematical model is Page model in hot air drying of kiwi according to the comparison of root mean square error (RMSE), chi-square (?2) and model efficiency (EF) values obtained by modeling of drying data. It was determined that the most suitable mathematical model is GAB model for the sorption behavior of kiwi fruit. The effective diffusion coefficient values ranged from 2.73936 x 10-10 (50 ?C) to 3.89772 x 10-10 m2 s-1 (70 ?C) depending on the temperature. © 2020, TUBITAK. All rights reserved