ABSTRACT: The effects of microwave intensity, chamber pressure and other parameters on mass and heat transfer during chestnut drying under microwave drying equipment were studied. Box-Behnken central combination experiment design was used to determine the optimum parameters of microwave power, pressure and drying time in the process of microwave vacuum drying of chestnut, taking moisture content and whiteness as evaluation indexes.
The results showed that the microwave vacuum drying process of chestnut was mainly accelerated and decelerated, and the duration of constant-speed stage was shorter. Microwave power and vacuum degree have significant effects on drying time. The higher the power, the higher the vacuum degree and the faster the drying rate. The moisture content and moisture ratio of dry base gradually decrease with the extension of drying time. According to the regression model, the optimum microwave vacuum drying parameters of chestnut were obtained as follows: time 12 min, pressure 56 kPa and power 3 kW.
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