红心火龙果热风干燥动力学模型及品质变化

为提高红心火龙果干燥效率及产品品质,研究了不同火龙果片厚度(6、8、10、12mm)和干燥温度(50、60、70、80℃)条件下火龙果片干燥特性和品质变化。结果表明:厚度越小,干燥温度越高,火龙果片的干燥速率越快,干燥时间越短。通过模型拟合发现,Page模型能够较好地反映热风干燥过程中火龙果片水分比随厚度和干燥温度的变化。红心火龙果片有效水分扩散系数在3.5374×10~(-10)~19.9426×10~(-10)m2/s之间;厚度为6、8、10、12mm时,对应的活化能分别为32.9857、27.0861、26.8894、17.7929kJ/mol。在干燥温度70℃、切片厚度6mm、干燥时间6h下,火龙果片的总酚含量和抗氧化能力较高。干燥温度和切片厚度对火龙果片色泽影响不明显。

Hot-Air Drying of Red-Fleshed Pitaya: Kinetic Modelling and Quality Changes

In order to improve the hot-air drying efficiency and the product quality, the drying characteristics and quality changes of red-fleshed pitaya were evaluated at different slice thicknesses (6, 8, 10 and 12 mm) and drying temperatures (50, 60, 70 and 80 ℃). The results showed that higher temperature and thinner slices led to higher drying rate and shorter drying time. The Page model could well reflect the change of moisture ratio with thickness and drying temperature during hot air drying. The effective moisture diffusion coefficient of red-fleshed pitaya ranged from 3.537 4 × 10-10–19.942 6 × 10-10 m2/s. The hot-air drying activation energy for 6, 8, 10, and 12 mm thick pitaya slices were 32.985 7, 27.086 1, 26.889 4 and 17.792 9 kJ/mol, respectively. Higher total phenol content and antioxidant activity were observed for the dried product obtained at drying temperature of 70 ℃, slice thickness of 6 mm and drying time of 6 h. Drying temperature and slice thickness had no significant effect on the color of the product.