Microwave Drying Characteristics and Moisture Content Prediction of Hawthorn

This study aimed to explore microwave drying characteristics and realize moisture content prediction of hawthorn during drying process. The effects of drying temperature (50, 60, 70 ℃) and relative humidity (5%, 15%, 30%, 50%, 70%) on the drying characteristics and quality of hawthorn were studied. Extreme Learning Machine (ELM) was established to predict hawthorn moisture content. The results showed that the optimum drying conditions were 60 ℃ and 30% relative humidity. The color changed the least, the content of V_C was the highest, and the content of total flavonoids was higher for hawthorn. The model of ELM with the structure of “3-8-1” was established to predict moisture content. The determination coefficient R² value was 0.996 and root mean square error RMSE was 0.00952 between predicted value and experimental, which could effectively predict the moisture content of hawthorn during microwave drying. The results would provide a theoretical basis for microwave drying application and on-line moisture content prediction of hawthorn.