Tea Manufacturing & Process

For Non-orthodox Tea.

By: Sabbir Ahmed Shawon. Food Engineering And Tea Technology Department.

Shahjalal University of Science &

Technology. Sylhet, Bangladesh.

Basic Steps of Processing & Manufacturing:

Withering. Rolling. Fermentati

on. Drying. Shorting. Tea Tasting Packaging

Plucking can be done by two ways:

PLUCKING

Hand Plucking• Standard plucking table is two leaves and a bud.• Longer the shoot considered to be course plucking. • High amount of tannin• High amount of caffeine• High amount of polyphenol oxidase• Less amount of moisture.

Mechanized Plucking.

• It done by plucking machine.• Includes a large beg at the end of the machine.•Save time and labor cost.• Tea Quality hampered because of course plucking

WITHERING

• Withering means partial removal of moisture of fresh leaf.

• Leaf consisting (74-80) % moisture and (20-26) % solid matters.

• After withering moisture level reduce down to (55-60) %.

• Helps in smooth operations of the rest manufacturing processes.

Physical Changes In Withering:• Moisture loss

through stomata pore.

• Young leaves wither earlier than the old leaves.

• (3-4)% of solid substance of dry weight loss due to respiration

Physical Wither Can Be Achieved In 3-4 Hours But

Chemical Wither Requires 12-16 Hours.

Bio-chemical Changes In Withering :

• Increase polyphenol oxidase activates.

• Breakdown the chlorophyll and proteins to amino acids.

• Increase the level of organic acid.• Increase permeability of cell

membrane. • Oxidation of carbohydrates, fats,

& other soluble component to carbon-di-oxide, water and energy.

Withering system:

• Natural withering: Includes chung or rack withering.

• Controlled withering: Includes drum, tunnel, trough withering.

Withering Trough:

• Invented by the tea planter, Deson in Zaire.

• It made of bricks, concrete, wood or metal. And Consist of a long trough, single or double hot air flow system.

Working principle:A fan is provided with the

heating arrangement to flow hot air along the trough. Absorbing this heat, moisture presents in fresh leaf start being evaporated.

The Troughs Are Of Two Types –

• Open trough: In the open type of trough, leaf is spread at a given thickness and air is blown upwards from the bottom of the perforated bed.

• Enclosed trough: In the enclosed troughs the leaf bed is kept in an enclosed environment by raising the sides of the withering troughs and using a cover on top of the bed. This is designed to create a plenum chamber on top of the leaf bed as well. In this case the fan is always made to blow air only in the forward direction and air can be made to pass either from top to the bottom or from bottom to the top with damper and shutter control at the air entry and exit points respectively without reversing the direction of the fan. The chance of leaf damage in enclosed trough is much lower.

Field Tests For Perfect Withering:

• When a handful of fresh leaves squeezed and emit, a carking sound or stems break down indicates incomplete withering.

• When a handful of fresh leaves squeezed and emit, if it springs back, it indicates incomplete withering.

• If it retains its shape as a compact ball, it indicates well withered.

RollingRolling is a process to reduce the leaf size & disrupt the cell wall

and expose their contents to start the process of oxidation.

The Objectives of

Rolling :• Press out the juice from leaf in such a manner that leaf does not break up too quickly.

• Rupture the cell walls and mix the chemical components for subsequent fermentation.

• Make a homogeneous process of oxidative reaction.

• twist the leaf and give it the desired shape or appearance .

Methods Of Un-orthodox Tea Rolling: • Lawrie the processor (L.T.P)• CTC(crush, tear & curl)• The rotor vane• The leg cut machine.• The boruah continuous roller.As CTC and the rotor vane machine

are widely used through the world, we are here gong to show you only these

two type methods.

Principle of Working (CTC):

The triple process of Crushing, Tearing and Curling is done by the teeth on the two rollers moving against each other at differential speeds. The slower roller rotated with 70rmp and for the fast one with 700rpm. Preconditioned leaf is fed to the slow speed roller. The another roller imparts a relative motion between the surface of two roller with leaf in between. The leaf comes out though bottom- crushed, torn and curled.

CTC(crush, tear & curl) Machine

Fermentation.

Is a process of oxidation of various

chemical constitutions of tea leaf through a

series of chemical reactions.

Objectives Of Fermentation:• Oxidation of polyphenol.• Formation of Theaflavin

and Thearubigin.• Development of aroma

and flavor.

Principal Reactions Process: The six catechins (a type of

polyphenol) present in tea shoots are.

• Catechin (C), • Epicatechin (EC), • Epicatechin

gallate(ecg), • Gallocatechin

(GC), • Epigallocatechin

(EGC), and • Epigallocatechin

gallate (EGCG).

These catechins are oxidized by Polyphenol Oxidase(PPO) and form Theaflavin(TF) and

Thearubigin(TG).

Theaflavin is orange red in color and Thearubigin is red

brown in color.

Formation of Theaflavin and Thearubigin ratio is 1:10.

Enzyme Dependent Reactions:

These reaction results: • The formation of theaflavin(TF) and Thearubigin(TG).• Development of aroma and flavor• Breakdown of chlorophyll• Change in carotenoids, organic acids and nucleotides.

Basic reactions which occur during the formation of Theaflavins are-

EGC + EC + O2 = Theaflavin + CO2

EGCG + EC + O2 = Theaflavin-3 monogallate + CO2

EGC + ECG + O2 = Theaflavin -3'- monogallate + CO2

EGCG + ECG + O2 = Theaflavin 3'3' digallate + CO2

Theaflavin Monogallates Are More Brighter And Brisker Than Theaflavin

And Theaflavin Digallate Is Much More Brighter And Brisker Than Theaflavin

Monogallate

Thearubigins (TR) are formed by action of peroxidase (PO) from the same catechins, but the reaction is much more complex. It is a complex mixture of carbohydrate, oxidized polyphenols, and nitrogenous compounds. TRs are also formed fromTFs. The chemistry of thearubigins is highly complex and their structures have not yet been established. When the TFs start getting oxidized to TRs, it has deleterious affect on quality. Thus the skill in carrying out the oxidation leads to formation of a right combination of TFs and TRs to give brightness, body and colour of black tea, but unless the epigallates are present in sufficient quantities, the desired TFs cannot be formed.

It includes the interaction of

oxidized polyphenols and sugars with amino acids, the

tanning or enzymes and other proteins,

reduction of the number of micro-

organism.

Non-enzymatic Chemical Reaction:

Temperature 27°-29°C (80-84°F)Adequate supply of oxygenTime: 40-90 minutes.Relative humidity: not less than 95%Hygrometric difference: 1.1°

Process Requirements

Meth

od

of

oxid

ati

on

Conventional

Floor

Rack

Aluminum sheet

Modern

Trolley trough

Drum

Continues fermenting

Continues Fermenting System.

Drying: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.

Mechanism of drying:1.Constant rate period: surface moisture removed by evaporation. 2. Falling rate period: core water removed by diffusion.

Chemistry Of Drying :

In the final stage of black tea processing following chemical changes take place: • By the deactivation of enzyme like

Polyphenol Oxidase (PPO), Peroxidase (PO), etc. almost all the biochemical reactions are brought to an end. However, as the temperature rises to the level for destroying enzymes, the particular enzymes get activated and faster reaction takes place in the initial stage of drying. If the temperature is raised slowly, TR is likely to be formed.

• Chlorophyll is degraded to pheophytin and pheophorbide at elevated temperature during drying contributing towards the blackness of made tea.

• At elevated temperature, by binding with proteins, Polyphenols make complex chemicals, which brings down the level of astringency.

• Interaction between carbohydrates with amino acids at elevated temperature leads to the formation of flavor components.

Shorting And Grading.

Removing fiber:

• The fiber extractor machine works on the principle of static electricity.• The pic roller in fiber extractor

machine acts as a positive charge and fiber acts as a negative charge, then both attract each other and fiber is collected from the roller.

Name of tea grade and its mesh size in CTC

Grade NameMesh Size

Bellow AboveWhole leaf grade FOP- Flowery Orange Pekoe - - OP- Orange Pekoe - -Broken grade FP -- Flowery Pekoe/Pekoe 8 10 FBOP- - Flowery Broken Orange

Pekoe10 12

BOP- Broken Orange Pekoe 12 16Fanning Grade OF- Orange Fanning 16 20 FOF- Flowery Orange fanning 20 24Dust grade PD- Pekoe Dust 24 30 RD- Red Dust 30 40 SRD/D-Super Red Dust 40 50 CD- Churam0ni Dust 50 60

Tea taster tastes each grade on different criteria like

mouth feeling and type of residue

Tea Tasting

• Physical appearance• Infused tea leaf• Taste.

Decoction :

About 2 gm of tea per 100 ml of water is weighed into porcelain pots provided with lids. Water, which has just reached boiling point, is then poured into the pots as quickly as possible. Speed is necessary at this stage to ensure that even the last tea for examination receives water, which is still boiling.Tea is allowed to infuse for exactly five or six minutes or whether exactly 2 gm of tea is added to each pot provided .

Maximum amount of tea should be packed in the container because oxygen and moisture in the free space promotes bacterial growth and enzymes are regenerated affecting the TFs in particular. After filling, the containers should be closed promptly.

Packaging

For references:

1. Tea cultivation: Comprehensive Treatise: N. G. Hajra

2. Tea culture, processing and Marketing: M.J. Mulky

3. Tea Science: D.L. Sana

4. Tea Estate Management: M.L.Rahman

THANK YOU