Tea drying process reduces moisture content from the fermented and rolled tea leaves to attain the moisture level of dried black tea. The process that is completed by use of a tea dryer also allows tea to attain a pleasant aroma. Drying process is achieved by injecting hot air through the fermented leaves which are then conveyed by use of a conveyer chain.
The working principle of fluid bed dryer during tea drying process
In a fluid bed dryer, the tea leaves are kept between hot air; which causes rapid drying. The gas in the tea dryer is allowed to move upwards through a bed of tea leaves at a greater velocity than the set velocity of the tea leaves. The leaves are partly suspended in the dryer’s gas stream. The subsequent mixture of solids and gas makes the leaves to be fluidized.
Each individual leave is deal with by the drying gas thus allowing the drying process to occur in much shorter period. Movement over the powerful mixing process between the leaves and hot air ensures uniformity in the composition, temperature and leaves size distribution
In the fluidized bed tea dryer, gas or hot air is passed at great pressure via a perforated bottom of the container comprising of tea leaves to be dried. The tea leaves are suspended in streamed air and elevated from the bottom. This stage is called fluidized state. The hot air in the tea dryer surrounds all leaves to wholly dry them, thus materials are uniformly dried.
What the actual process entails
The tea drying process is what is responsible for numerous new flavor compounds and improvement of tea appearance. The tea dryer removes the excess moisture in the tea leaves as the leaves moves to the next stage.
The various drying machines used
Fluid bed dryer- These make use of perforated conveyors and fluidized bed dryers that are used to pass the leaves through a heating system in a chain; where the leaves are dried on hot air bed.
Oven dryer- tea leaves are set on top of perforated trays in oven; where hot air is circulated via convection. The tea drying process makes the oxidative process slow and the air temperature is controlled to produce a palatable tea.
The process of tea drying is not as simple as many may think as it requires huge investment in machinery and capital to make it work. All in all, choosing the best tea dryer is a head-start when thinking of setting up a tea drying plant.