Technology Trends in Tea Manufacturing

Tea plucked from the garden is sent to the factory for processing, which in most cases, is in or near the tea

Tea plucked from the garden is sent to the factory for processing, which in most cases, is in or near the tea garden. This processing, earlier, used to depend solely on the natural weather conditions, but to become less dependent on the unpredictable weather conditions which affects productivity adversely, modern technology has been introduced in the tea industry. This has made it possible to increase the plantation area by minimizing space; also labour cost has come down and the entire process has become much more speedy.

The starting material in black tea processing is the young shoot, the terminal bud and the two adjacent leaves plucked from the tea plant. The flush is processed in four distinct stages, which are withering, rolling, fermentation and drying. Each stage involves characteristic changes in the physical and biochemical composition of the leaves and the cumulative effect of these changes are ultimately reflected in the quality of the finished product, namely the black tea. After the drying is over, the leaves are sorted, that is, divided into different grades and made ready for the market.

Plantations :Unlike other perrenials, tea is unique because only its vegetative parts - the two leaves and the bud - are commercially exploited. Tea is also maintained as a low bush in a continuous phase of vegetative growth. Both these aspects call for manipulation of plant parts for optimal productivity and growth.

Plucking & Leaf Handling : The plucking of the two leaves and a bud involves a number of systems - Janam plucking, fish-leaf plucking , step-up plucking etc.. Shear plucking is done when there is a scarcity of pluckers during July to September. Pluckers' productivity is found to be maximum in unpruned teas. The plucked leaves are processed to produce the black tea.

Withering : It is a procedure which brings about physical and chemical changes in the shoots to produce quality, apart from conditioning the flush for rolling by reducing turgor, weight and volume. Previously the flush used to be withered under the sun. Now this process is generally achieved either by thinly spreading the flush on mats, or in thick layers in troughs for 8-18 hours depending on the condition of the leaves.

Rolling : The object of rolling is to macerate the leaf so that the enzymes and their substrates get intimately mixed up. This is achieved mechanically either by the use of an orthodox roller, the rotorvane, or by CTC (crushing,tearing and curling) machines. Rolling ruptures the cell wall thereby enabling the production of enzymes.

Fermentation : It is the process of oxidation of leaves. The mechanical aspect involves spreading out of the leaves macerated by rolling a layer 5-8 cms thick, for 45 minutes to 3 hours, depending on the quality of the leaves. Fermenting machines make the process continuous, that is, every unit of macerated leaf has to be spread out for individual treatment.

Drying : It reduces the moisture content of rolled and fermented leaves from 45-50% level to a 3% level in dried black tea. It also allows development of black tea aroma. Drying is physically achieved by blowing hot air through fermented leaves as they are conveyed in chains. The drying process lasts for about 20 minutes.

Sorting : Sorting may be defined as a procedure in which particles of bulk tea are separated into grades of different sizes. This sizing can be done either manually or by using different sizing equipments. Sorting meshes of various sizes are used to grade the tea.