The effects of freezing pretreatments on drying kinetics and qualitative properties (shrinkage, rehydration, color, texture, total phenol content, antioxidant activity) of hot air dried grapes were studied. Results showed that the use of a freezing pretreatment before grape drying reduced the shrinkage (from 84 ± 1 to 72 ± 1%), color changes, firmness (from 1.7 ± 0.1 to 0.9 ± 0.1 N), drying time and increased rehydration, total phenol content (from 9.1 to 10.7 mg/g), antioxidant activity, effective moisture diffusion coefficient and activation energy ((from 27 ± 3 (control samples) to 36 ± 3 (samples treated using cryogenic freezing) and 37 ± 3 kJ/mol (samples treated using conventional freezing)). Whereas, increasing the drying temperature increased the shrinkage and firmness. The Page model with the highest correlation coefficient and lowest root mean square error and chi-square was selected as the best model. Freezing cracks were observed in both conventional and cryogenic freezing samples using scanning electron microscopy.

研究了冷冻预处理对热风干燥葡萄干燥动力学和定性性能（收缩，补水，颜色，质地，总酚含量，抗氧化活性）的影响。结果表明，在葡萄干燥前使用冷冻预处理可减少皱缩（从84±1降低至72±1％），颜色变化，硬度（从1.7±0.1降低至0.9±0.1 N），干燥时间和增加补水量，苯酚含量（从9.1至10.7 mg / g），抗氧化剂活性，有效的水分扩散系数和活化能（（从27±3（对照样品）到36±3（使用低温冷冻处理的样品）和37±3 kJ / mol （使用常规冷冻处理的样品）。但是，提高干燥温度会增加收缩率和硬度。选择相关系数最高，均方根误差和卡方最小的Page模型作为最佳模型。使用扫描电子显微镜在常规和低温冷冻样品中均观察到冷冻裂纹。