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

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 79.85 kJ/mol. The effective diffusion coefficients of lotus seed was ranged from 8.9891×10^-10 to 2.22431×10^-9 m²/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.