Abstract

This paper studies the characteristics of microwave vacuum baking and drying of oolong and analyzes the influence of microwave power and vacuum degree in the drying process on the moisture in the tea. According to the variation law of moisture, it explores the relationship between time and wet base moisture contents under different microwave powers and vacuum degrees, as well as the kinetic mathematical model of vacuum drying for oolong using the microwave. Based on the energy balance between the sensible heat, latent heat and the absorptive microwave energy, this model builds verification test by a large number of experimental data and the results indicate that within certain range of radiation power and thickness, the temperature and moisture content of oolong are uniformly distributed, even more uniform especially in the drying period; generally, the temperature distribution within the oolong fails to show integrity. The free water and water vapor may flow as permeate stream in the internal part of oolong under the action of pressure gradient. The migration intensity mainly depends on the intensity of microwave radiation and initial moisture content; the mathematical model established on this basis could better simulate the microwave vacuum drying process of oolong. Due to its high simulation accuracy, it can be used to describe the variation of moisture content with the drying time and power. The test results provide a technical basis for the controllable industrial production of oolong baking.

Keywords:

Drying characteristics, kinetic model, microwave vacuum baking, oolong,

References

Competing interests

The authors have no competing interests.

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Copyright

The authors have no competing interests.