Abstract This study examined the performance of different combined infrared (IR) and hot-air drying (HAD) strategies for sweet potato. Experiments were conducted for simultaneous infrared and hot-air drying, two-stage sequential hot-air and infrared drying, two-stage sequential infrared and hot-air drying, and intermittent infrared and hot-air drying in a laboratory scale combined infrared and hot-air dryer. The drying air temperature varied between 50 and 70 °C, the infrared intensity was 1100 W/m2, the air-velocity was 1.5 m/s, and the pulse ratio (PR) ranged from 1 to 3. Results indicated that the drying rate, drying time, effective moisture diffusivity, shrinkage, specific energy consumption (SEC), colour attributes and phytochemical compounds of sweet potato were affected by the different drying combination strategies. The drying kinetics, product shrinkage, and sample temperature were also influenced by drying time and air temperature. The two-term exponential model adequately explained the drying behaviour of sweet potato for all the different combination strategies. The intermittent IR and HAD combination strategy proved to be the most suitable based on the combined effect of total drying time (113–120 min), SEC (27.67–41.44 kWh/kg), total colour change (17.15–26.48) and bioactive compounds.

中文翻译：

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红外和热风联合干燥策略对甘薯的有效性

摘要 本研究考察了不同组合红外 (IR) 和热风干燥 (HAD) 策略对甘薯的性能。在实验室规模的红外热风联合干燥、两段顺序热风干燥、两段顺序红外和热风干燥、间歇红外和热风干燥实验中进行了实验。烘干机。干燥空气温度在 50 至 70 °C 之间变化，红外强度为 1100 W/m2，风速为 1.5 m/s，脉冲比 (PR) 为 1 至 3。结果表明干燥速率甘薯的干燥时间、有效水分扩散率、收缩率、比能量消耗（SEC）、颜色属性和植物化学成分受不同干燥组合策略的影响。干燥动力学，产品收缩率和样品温度也受干燥时间和空气温度的影响。两项指数模型恰当地解释了红薯在所有不同组合策略下的干燥行为。基于总干燥时间（113-120 分钟）、SEC（27.67-41.44 kWh/kg）、总颜色变化（17.15-26.48）和生物活性化合物的综合影响，间歇性 IR 和 HAD 组合策略被证明是最合适的.