DRYING EFFECTS OF TWO AIR-DRYING SHELTERS IN A PILOT TEST ON SULTANA GRAPES

The drying effects of sultana grapes in two different air-drying shelters were tested and analyzed. Ten different thin-layer drying mathematical models were compared according to their coefficients of determination and chi(2) test. The Wang and Singh model was found to be the most suitable for describing the air-drying curves of sultana grapes. As compared with the local traditional shelter, the reformed shelter with a greenhouse can reduce about 12-18% of air-drying time, increase about 23% in green-grade rate of raisins and increase 33% in the effective moisture diffusivity of sultana grapes.