Drying Characteristic of Apple Slices Undertaken the Effect of Passive Shelf Solar Dryer and Open Sun Drying

Abstract

Apple Varity (Golden Delicious) is widely cultivated in Syria and is consumed either fresh or in the form processed products such as juice, marmalade, jam and less as dried product. The present study was conducted to investigate the drying characteristics of apple slices and the quality parameter of apple slices (color, Rehydration ratio) undertaken the slice thickness (5, 10 mm) pre-treatment and the drying method by using a Passive Shelf Solar Dryer (PSSD) and in the Open Sun Drying (OSD). Results showed that there is a significant effect of the drying method and slices thickness on the moisture content and the drying time. The drying time decreased by 40% for 5 mm thickness of slices in the (PSSD) drying system comparison to the (OSD) system and the drying time decreased by 22% for 10mm thickness of slices in the (PSSD) drying system comparison to the (OSD) system. The slices thickness has a significant effect on the drying time where, the drying time for 5 mm thickness was less by 80% comparing to 10 mm in the passive solar dryer and less by 57% in the open sun drying. Rehydration ration also affected by the slices thickness and the slices treating by ascorbic acid, where the rehydration ratio values at the drying air temperature of 40°C increased by 41.7% and by 33.3% for treated and untreated slices when the slices thickness increased from 5 mm to 10 mm respectively.