Influence of Drying Methods on Drying Kinetics and Color Parameters

Abstract

Deveci pear (Pyrus communis L. cv. Deveci) slices, whose initial moisture content is 5.24 ± 0.003 kgsu kgKM-1 (%83.95 ± 0.01 w.b), were dried by shade drying and hot-air drying at 60, 80 and 100°C until the final moisture reached 0.13 ± 0.001 kgsu kgKM-1 (%11.40 ± 0.06 w.b), and the drying processes of these methods were completed in 11150, 437, 252, and 148 minutes, respectively. In the study, experimentally obtained time-dependent moisture ratios were modeled using twenty different thin-layer drying equations. Accordingly, the model that gives the closest results to experimental data for 60°C and 100°C was the Modified Henderson & Pabis's equation. On the other hand, Alibas equation and Jena & Das equation were found to be the best models in shade drying and hot-air drying at 80°C, respectively. Despite no energy consumption in the shade drying method, some reasons such as this method being quite long and causing negative effects on the quality parameters of the product revealed that the shade drying method was not suitable for drying of Deveci pear. It was observed that total energy consumption increased with the increase of the drying temperature. Also, it was determined that the increase in temperature negatively affected the quality parameters. It was found to be a suitable method for drying the Deveci pear of the hot-air drying at 60°C due to the operating parameters such as drying time and specific energy consumption, as well as quality parameters such as brightness, redness, yellowness, chroma, hue angle, total color change and browning index were very close to the fresh product.