Tea Withering

Withering is the first processing step in the factory and is a process in which freshly plucked leaf is conditioned physically, as well as, chemically for subsequent processing stages. Indeed, withering is one of the most important tea production process steps and can be said to constitute the foundation for achieving quality in tea manufacture. Based on achieving the desired level of withering, one can make better quality teas and, on neglect, can invite serious problems in subsequent steps of manufacture.

Withering Process

On Withering Process need Chemicals as follows:

• Chemical Wither: Desirable biochemical changes from plucking to initiation of processing (manufacturing), normally 14-20 hrs.
• Physical wither: Moisture loss, leaf becomes flaccid.
• Percent wither (% wither). The weight of 100 kg fresh leaf at the end of the withering process. Different % moisture contents of fresh leaf results in different % moisture contents of withered leaf, even when the "% wither" remains the same:
• Fresh leaf Withered leaf, i. e. 100 kg fresh leaf reduced to moisture. Percent wither can be calculated by measuring the recovery % of made tea against withered leaf.
• Fresh leaf moisture Recovery % of tea made against withered leaf (theoretical)
• The same recovery % indicates light wither on dry leaf . Fresh leaf moisture content determines withering (and drying) loads; 8 percentage points less moisture results in 40 - 45% increase in recovery .

Example : At 80% wither, a reduction from 82% to 74% moisture gives an extra 10 on 22, i.e. 45%.

Tea Maceration

The principal objective of leaf maceration is to undertake cell rupture carried out in a rolling machine where progressive disintegration of cellular organelles takes place. The process results in exposure of cell sap leading to intermixing of chemical constituents and enzymes in the presence of atmospheric oxygen to form the important chemical constituents responsible for characteristics of tea. From the moment the maceration starts, the ‘fermentation’, which is primarily an oxidation process, begins. The shoot with different degree of tenderness is subjected to considerable deformation during rolling, and, during the process of gradual rupture of leaf, the epidermis is torn up in pieces, cells are crumpled, the cuticle wrinkled and the intercellular space is increased. The mechanical breaking of shoots at this stage also results in the formation of particles of various shapes and sizes depending on the method adopted and the extent of cell damage.