DRYING EFFECTS OF TWO AIR-DRYING SHELTERS IN A PILOT TEST ON SULTANA GRAPES
Abstract
ABSTRACT
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 andχ2test. 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.
PRACTICAL APPLICATIONS
Grapes are one of the most popular and palatable fruits in the world. The preservation of grapes by drying is a major industry in many parts of the world where grapes are grown. Drying grapes, either by open sun drying, shade drying or mechanical drying, produces raisins. Air-drying of solar energy has been demonstrated to be cost-effective and could be an effective alternative to traditional and mechanical drying systems, especially in locations with good sunshine during the harvest season. The traditional air-drying shelter of grapes has been used for thousands of years in Asia and other places around the world. However, less investigation was done about the drying characteristics and the optimization of the shelter. The work of this manuscript provides interesting information that is useful for design of the drying shelter of raisins and for the improvement of raisin quality, especially using air-drying of solar energy.
