Application of Microwave Technology in Modern Tea-making Industry

- May 07, 2019 -

Tea processing has very broad prospects for development. In recent years, there are many reports at home and abroad about the use of microwave technology in tea green killing, drying and extraction of effective ingredients. As one of the modern tea deep processing technologies, microwave application technology has begun to develop into large-scale production. Since the discovery of microwave heating effect in 1945, microwave heating has been widely used. Because tea contains water, water molecule is polarized in microwave electromagnetic field and has dipole characteristics. With the frequency of electromagnetic field, the polarity direction is constantly changed. The molecule vibrates at high speed and generates frictional heat, which warms the tea from deep inside, and the temperature is the same everywhere. With this characteristic of microwave heating, tea can be heated rapidly, reach the critical temperature of inactivating enzyme, and accelerate the migration of structural water in tea. It is very suitable for green tea green-killing process and tea late drying operation. It can be seen that microwave technology is an ideal way for tea green-killing and late-drying. The key to its application is how to match microwave frequency, power, material running speed, structure of microwave heating equipment and research the technical specifications of microwave technology for tea green-killing and drying.

Microwave defoliation and drying is a microwave generator that radiates microwave radiation into the defoliated and dried materials and penetrates them into the interior, which induces polar molecules such as water to rotate synchronously, rotating billions of times per second. As a result of such high-speed rotation, the material instantaneously generates friction heat, which causes the surface and interior of the material to rise at the same time, and the interior temperature is higher than the surface temperature of the material, which makes the enzyme lose its activity and part of the water molecules evaporate at the same time, so as to achieve the purpose of killing and drying. The characteristics of this method are short heating time, the same temperature inside and outside, the same direction of heat transfer from inside to outside and the same direction of moisture transfer. It takes a certain time to heat the heat from outside to inside of the material unlike the conventional heating method. There are problems of temperature difference between inside and outside and opposite direction of moisture and heat transfer. Microwave can penetrate into the internal heating of materials and does not need high-temperature heat medium. When applied to tea processing, it fundamentally changes the conventional heating mode depending on high-temperature medium and heat conduction mode. At the same time, because microwave electromagnetic field has non-thermal effect in the process of killing and drying, it greatly shortens the processing time and shows the unique advantages of microwave.

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