Plantation Crops

Process of tea manufacturing

Irrespective of the method of manufacturing tea it involves following steps

Manufacture black tea either by the CTC (Crush, Tear and Curl) or the orthodox method involves steps viz.,

1) Withering: Moisture content of leaves is reduced (to about 55 %) by drying in a trough receiving artificial air. Duration of drying varies from 12 to 18 hours.
2) Rolling: During rolling cells of leaves are broken to liberate sap containing polyphenol
oxydase ( and enzyme). Rolling takes place for about 30 to 40 minutes.
3) Fermentation: Rolled tea material is spread on concrete floor or trays under high humidity and proper temperature to undergo fermentation. Properly fermented tea will attain golden red colour deciding the quality of tea. Theaflavins: and Thearufigens are compounds responsible for colour of tea.
4) Drying: Slow reduction in moisture content as to stop fermentation process. Moisture
content is reduced to about 4 per cent. Duration of drying is for about 30 to 40 minutes.
5) Cleaning & grading: Remove stalky fibers and grade the tea by passing through different sized meshes.


1) Withering: The first step in processing of black tea is withering.

The main objective of withering is
1) Reduce moisture content of tea leaves: It lowers moisture content to about 55 per cent (by
removing 15 to 20 % moisture). During this the leaves undergo physical and chemical withering. Leaves are withered in troughs for about 12-18 hr.
2) When leaves have been withered correctly, it becomes flaccid and suitable for rolling during which polyphenols are mixed with enzyme polyphenol oxidase (PPO).

Judging the end point of withering

• No cracking sound: Well withered leaves will not produce any cracking sound when squeezed i.e., it must not be too dry.
• Compact ball: Withered leaves when pressed by hand should form compact ball.
• No brittle stalk: The stalk of the withered leaves should not be brittle.
• Feel test: Withered leaves will have silk hand kerchief feel to touch.
Withering may be of

1) Natural or Chung withering: 18 to 20 hours
2) Artificial withering: 3 to 4 hours.

Chemical changes during withering

a) Chemical changes: A slight increase in caffeine and a relatively large increase in some of the amino acids are the earliest chemical manifestations. The extent of chemical changes in the tea is more in natural wither, less in artificial wither and least in wither under humid conditions.
b) Quality: The chemical changes during withering and the degree of wither of tea shoots are partly responsible for the liquor characteristics, physical appearance and overall quality of the made tea.

Black tea

Withering is not considered essential for the manufacture of black tea although it does have an influence upon the appearance and quality of the finished product.


2) Rolling:

Leaf damage

The withered leaf is passed on to rollers where it is twisted so as to cause sufficient damage to the individual leaf cells and to initiate enzymic oxidation.
1. Duration and extent of rolling : Rolling is usually done for 30 minutes and the rolled mass is sifted and the finer portions of the leaf are allowed to ferment
2. While the coarser portions are subjected to heavy rolling. Rolled for 3 to 4 times.
3. Sometimes a third rolling may be given; rolling is essentially a batch operation. Due to rolling the catechins ( Polyphenol ) are thoroughly exposed to the polyphenol oxidase. (PPO)

Three major manufacturing methods commonly used are

i) Orthodox.: Which employs non-cutting rollers. The orthodox tea has superior flavour but poor in colour.
ii) Crushing, tearning and curling ( CTC) which employs rotoravanes and cutting rollers. CTC tea is more economical with red colour and popular in India.

3) Fermenting ( enzymetic oxidation )

Actually fermentation starts /commences at the time of rolling and continues till the entry into the driers.
The main operation in the manufacture of black tea is enzymatic oxidation which was originally termed fermentation and the term is still in vogue today. In tea processing, fermentation is the term employed to denote enzimatjc oxidation, by which the polyphenols in the leaf get oxidized with the help of PPO (Polyphenol oxydase).



Method of fermentation : The coarse and fine fractions of the rolled leaf are spread on clean cement floors or other suitable platforms to a thickness of 2.5- 10.0 cm depending upon the season and condition of the leaf, and allowed to ferment for 2-4 hours depending upon the type of roller used.

Compounds formed during fermentation process

1) Theaflavins (TF) === Orange red.
2) Thearubigins (TR) === Darker brown.
The quantity of TR and TF formed will be related to the period of fermentation and the temperature of fermenting leaves.

4. Drying or Firing

Objective of drying is to arrest fermentation.
Moisture of the made tea: The dried product contains 3-4 percent moisture, and can withstand long storage and transi

5) Sorting and Grading

The black tea is sold loose or in packets, under different brand names.
Stalk is removed during sorting. There are four main sizes, viz.,

• Whole leaf,
• Brokens,
• Fanning's and
• Dusts.
Packing and grading in tea:

• Dried tea is cleaned of stalk fibres (petioles/stalks/fibres) by passing through fiber separating machines.
• Bulk tea is passed through different meshes which aid in separation into different grades

Process involved in tea manufacturing