Effects of Different Drying Techniques on Drying Characteristics of Main Raisins in Xinjiang

【Objective】 To provide theoretical basis for improving the drying techniques of Xinjiang grapes: Thomson Seedless and Centennial Seedless, the effects of different drying techniques on the drying characteristics were studied in this paper. 【Methods】 The variation of moisture in drying and drying process was analyzed mathematically to study the drying characteristics of grapes. 【Results】 In the process of grape drying, the dehydrating rate during the day was 2.00-6.14 times higher than that of the night. In the early stage of the drying process, the dehydrating rate of grape in the mode of drying in the sun was 1.21-3.12 times as high as with shade-air drying. The effective water diffusivity of the sun-dried grape berry of the two varieties of grapes was 3.14 and 3.18 times higher than that of the shade-air-dried one. The effective water diffusivity of Centennial Seedless was higher than that of Thompson Seedless. The effective water diffusivity of Centennial Seedless and Thompson Seedless under sun-drying was 6.023,16×10^-8 m²/h, 2.615,45×10^-8 m²/h, and in shade-air-drying was 8.308,75×10^-9 m²/h,1.892,12×10^-8 m²/h.; 【Conclusion】 The drying rate in daylight was significantly higher than that during night under sun drying and shade-air drying. The effective water diffusivity of different drying processes and different drying grape varieties was obtained. The study results can provide a basis for the improvement of shade-air drying rooms in Xinjiang.