Tea Production Process

The Tea Production include of all these process, even for the traditional process is not mentioned about the process order, but actually they do of all these:

Withering Process:

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 processing 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.

Leaf 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. These factors have strong effect on the processing steps that would follow as well as market choices for the made teas. Therefore, leaf maceration is also a key step in tea manufacture.

Rolling Process:

Before the advent of tea machinery, the most convenient method for cell rupture was to rub the leaf in between palms. The Rolling table is simple equipment that emulates the hand rolling method in a commercial level operation. The process of rolling applies pressure and twist between leaves as well as between leaf and surface of the equipment used for rolling.

The degree of pressure depends upon the quantity of leaf charged as well as the position of the pressure cap. Resulting friction causes heat, which in excess will hasten the chemical reactions to result in the formation of undesirable constituents detrimental to the quality. The cell rupture in the small and tender shoots is completed faster and chemical reactions set in earlier while the coarser leaves require a little more time. Also the leaf, which has already undergone size reduction and twisting after some amount of rolling, impedes twisting of larger leaf, which may extend the period of rolling.

Segregation of such leaves is carried out after an appropriate period (30-45m). The leaf is discharged and then passed through a Sifter or a Ghoogie. The Ghoogies and Sifters have perforations of different sizes. The particles passing through the perforation are called fines and the spill is known as ‘Coarse’ leaf, which is sent for further rolling. The fine leaf is taken for ‘fermentation’. The coarse leaf after second roll is subjected to similar process to get the 2nd fine and if need be the 2nd coarse leaf may further be subjected to 3rd rolling. It may be noted that major portion of the leaf grades come from the coarse leaf.

Oxidation Process:

The principal difference between black teas and other forms of teas like green tea and oolong tea is the presence of condensed catechins, i.e. polyphenols of higher molecular weight formed through enzymatic oxidation with the help of enzyme polyphenol oxidase (PPO) and peroxidase (PO). The next process objective is, therefore, to allow intimate contact of the catechins with the respective enzymes, which oxidize these catechins in presence of oxygen. The temperature and Relative Humidity also have a role in these oxidation reactions and should be kept at a levels at which the enzyme activity is at the peak.

Drying Process:

The main objectives of drying are:

• To arrest enzymatic reaction as well as oxidation,
• To remove moisture from the leaf particles and to produce a stable product with good keeping quality.

Sorting Process:

 
Despite more or less intense sifting, bulk obtained after drying are still heterogeneous. Tea ranges in size from that of a speck of dust to a leaf approximately 4 cm long and 1cm wide. The fractions are to be brought to the desired sizes and forms with adequate uniformity and cleanliness conforming to trade requirement. Tea is, therefore, sorted into pieces of roughly equal size. Four main sizes are produced, namely, Whole Leaf Grades, Brokens, Fannings and Dusts. Within each of these sections tea is further split up into grades of varying qualities. Whole Leaf Grades are the largest sizes produced and depending on the actual grade within the section may range from a long and wiry stem, 1 cm to 2 cm in length, to a round and knobby twisted leaf similar in size and shape to that of a small garden pea. Of the former style there are the Orange Pekoes and long Leafed Pekoes.