基于控温的莲子微波干燥特性及干燥品质研究

Characteristics and Quality of Microwave Drying Lotus Seed based on Temperature Control

为了探索基于控温下的莲子微波干燥特性及干燥品质,研究不同微波功率、物料表面温度区间对莲子微波干燥特性的影响,对莲子进行了微波控温干燥试验,并将基于控温下的微波干燥莲子与热风干燥莲子在品质上进行了分析。研究结果表明:物料表面温度对莲子干燥影响较大,物料表面温度区间越大,莲子干燥速率越快,干燥时间越短;微波干燥功率对莲子干燥影响较小。采用7种常见的薄层干燥模型对控温微波干燥过程进行拟合,结果表明Midilli模型是最适合描述在莲子微波控温干燥过程中水分变化规律的薄层干燥模型。根据Fick第二定律得出莲子控温微波干燥的有效扩散系数为8.9891×10^(-10)～2.22431×10^(-9)m^2/s;由Arrhenius方程得出莲子微波控温干燥的活化能为79.85 kJ/mol。两种干燥方式干燥的莲子复水率差异不显著(p> 0.05);莲子控温微波最短干燥时间低于热风干燥。研究结果可为莲子控温微波联合干燥工艺提供参考。

The purpose of this paper was to investigate drying characteristics and quality of lotus seed in microwave drying process based on temperature control.The microwave drying experiment based on temperature control was carried out to analyze the effect of microwave power and material surface temperature range on drying characteristics of lotus seed,and compared the quality of hot air drying process with the quality of microwave drying process based on temperature control.The results showed that,the material surface temperature showed a great impact on drying characteristics of lotus seed.Higher material surface temperature would result in faster drying rate and shorter drying time.Microwave power showed little influence on drying characteristics of lotus seed.Seven common thin-layer drying models were used to fit the temperature-controlled microwave drying process.It turned out that the Midilli model was the most suitable thin-layer drying model that for describing the variation of moisture in the microwave-controlled drying process of lotus seeds.In addition,the activation energy values were 79.85kJ/mol.The effective diffusion coefficients of lotus seed was ranged from 8.9891×10^-10 to 2.22431×10^-9m^2/s.There had little different between the rehydration rate of hot air drying processed lotus seed and microwave drying processed (p >0.05).The shortest drying time of temperature-controlled microwave drying was lower than that of hot air drying.The results of this study would provide a reference for the microwave drying based on temperature control for lotus seed.