Drying of the Turkish Grape by Hot-Air

Preserving of food by drying, became an important subject in food industry. The aim of this work was to determine the effect of pretreatment on the drying rate and quality degree of product in drying operation of Sultana. Drying was done in a horizontal air flow drier. The air flow rate in the drier was 4.4 m/s in the first six experiments and 5.6 m/s in the other four experiments. The relative humidity of air used for drying was changing in the range at 10-20 %. The weight of Sultana and the wet and dry bulk temperature values were recorded during drying at every 15-20 minutes until constant weight. These values were used in calculating the moisture ratio and drying rate and in drawing the drying and drying rate curves. The good surface quality attainable for the samples used and the drying period were determined at the end of this work. The pretreatment operation, the difference between wet and dry bulk temperature values of air, the flow rate of drying air and the dry thermometer temperature values were determined to be the factors affecting the surface quality and the drying period in drying operation.