桑椹对流-红外联合干燥特性及品质变化研究

Effects of Combined Convective-infrared Radiation on Quality of Mulberries

摘要:

本实验研究了不同对流干燥温度（60、70和80 ℃）和红外功率（675、1350和2025 W）对桑椹对流-红外联合干燥特性和干燥产品品质的影响。结果表明：干燥温度对干燥速率影响较红外功率大；干燥过程属降速干燥，由费克第二定律求出桑椹有效水分扩散系数在2.67×10-9～8.41×10-9 m2/s范围内，并随对流干燥温度和红外功率的增大而增大；由阿伦尼乌斯公式计算出桑椹干燥活化能为53.99 kJ/mol；干燥实验数据拟合结果显示，桑椹的对流-红外联合干燥过程符合Page模型；且在对流温度70 ℃，红外功率675 W干燥条件下物料品质最优。相比热风干燥与真空冷冻干燥，对流-红外联合干燥大大缩短了干燥时间，具有最高的总酚含量（30.33 mg/g）和较高的花色苷含量（11.55 mg/g），提高了产品的营养品质。该研究为对流-红外联合干燥技术应用于桑椹干燥提供了理论依据。

Abstract:

The effects of convective-infrared radiation on the product quality of dried mulberries at different connective drying temperatures (60, 70 and 80 ℃) and infrared powers (675, 1350 and 2025 W) were investigated. The result showed that the connective drying temperature had a more significant impact on the drying rate. The drying process was a falling rate drying. The effective moisture diffusion coefficient of mulberries ranged from 2.67×10-9 m2/s to 8.41×10-9 m2/s according to Fick's Second Law, and it increased with increasing temperature and power. The drying activation energy of mulberry was 53.99 kJ/mol according to the Arrhenius equation. The experimental data regarding the combined convective-infrared radiation drying process of mulberries was fit according to the Page model. The best product quality was obtained under the conditions of 70 ℃ and 675 W. As compared with hot air drying and freeze drying, the convective-infrared radiation combination significantly shortened the drying time and improved the product quality, as indicated by the greatest total phenol content (30.33 mg/g) and greater anthocyanin content (11.55 mg/g). This study could serve as a theoretical foundation for convective-infrared radiation drying of mulberries.