Manufacturing process of instant tea

1. Instant Tea
Basura J Jayasundara

2. Introduction
 Instant tea can be produced from black, green or oolong teas which
originate from the same plant camellia sinensis.
 The difference between various instant teas is based on various methods
used to produce instant teas from above varieties.
 Instant tea also can be produced from the waste, leftovers generated in
leaf tea manufacturing process.
 Instant tea is manufactured by extracting the solids from tea and then
extracted liquor is clarified, concentrated and dried to powder.
 Hot water soluble and cold water soluble instant teas are found in the
market.
 Instant tea powder is a type of value added product and it can be used as
the ingredient for the beverage and other food product formulations.
 Instant tea powder is extensively used in large quantity in various tea
premixes

3. Manufacturing process of instant tea
 Process of the production of instant tea consists of the following operations
Raw Materials
Extraction
Decanting
Aroma Stripping
De-creaming
Concentration
Blending
Drying
Packing

4. Manufacturing process of instant tea
Raw materials
 The criteria for the selection of the raw material include raw material availability, processing
requirements, the market for which the tea is intended and the commercial restrictions placed
upon manufacture.
 Main types of raw materials used in the industry are processed leaves, fermented dhools, refuse
tea (BMF grade) in either black, green or oolong teas.
 Fresh leaves also used as the raw materials in some manufactures of instant tea.
Extraction
 The active substances of the tea leaves are extracted by means of aqueous extraction and are
carried out in hot water in batch or continuous extraction systems.
 Counter current extraction is commonly used in both batch and continuous forms. Batch-wise
countercurrent extraction is normally used for the processing of small amounts of material and in
continuously operating extractors, the solid material and the liquid (solvent) flow counter
currently.
 Temperature of extract water, time of extraction, proportion of tea and water, type of tea and
purification of water are the major factors affect on the extraction process.
 In this process tea leaves are fed into the lower end of the extractor and are conveyed upwards by
the rotation of the screw while the extracting water flows in the reverse direction.
 The solution coming from the extractor usually contains 3-5% solids, which is measured as brix
value.

5. Manufacturing process of instant tea
Decanting
• The soluble components are responsible for the taste, aroma and effect.
• In addition to the soluble components, there are insoluble substances also that
are not wanted in the end product.
• They have a negative impact on the appearance and therefore have to be
removed.
• The extracted slurry is subjected to pass through continuous decanters and
clarifier to remove the non-soluble suspended matter from the extract.
• Decanters are used for the separating large volumes of insoluble tea leaf
components from tea extracts in the pre-clarification process.
• In decanters, centrifugal force is used to separate solids from liquid efficiently in a
manner that is easy to control.

6. Manufacturing process of instant tea
Aroma stripping
 As tea aroma have important contribution to the acceptability of tea,
considerable efforts have been made to preserve the aroma in the instant
product.
 Therefore, volatile aroma compounds are stripped from the extract prior or
during evaporation and added back to the liquor before spray drying.
 If the aroma has not been stripped off the extract before concentration a
proportion of it will be removed with the steam.

7. Manufacturing process of instant tea
De-creaming
• Centrifuge is used in the instant tea manufacturing process to remove
fine particles from the extracted tea liquor.
• The centrifuge works using the sedimentation principle, where the
centripetal acceleration causes denser substances and particles to
move outward in the radial direction. At the same time, objects that
are less dense are displaced and move to the center.
• In the centrifugal separator, the effectiveness is increased with a stack
of conical disks for creating a large equivalent clarification area and
the force of gravity is replaced with a centrifugal force that can be
more than 5,000 times stronger than the force of gravity. Therefore,
the separation will be significantly faster.

8. Manufacturing process of instant tea
Concentration
• The liquor coming from the de-creaming process is too dilute to pass directly to a
drier. Therefore the liquor has to be concentrated, generally to 20-40% solids.
Concentration of tea extract is carried out by evaporation under reduced pressure.
Type of unit operation: Heat transfer operation
• The typical evaporator is made up of three functional sections: the heat exchanger,
the evaporating section, where the liquid boils and evaporates, and the separator in
which the vapour leaves the liquid and passes off to the condenser or to other
equipment.
• Single effect evaporator or multiple effect evaporators is used for the concentration
of tea extract. Multiple effect evaporator save energy by utilizing steam repeatedly.
• Concentration of tea is normally done through reduction of pressure. At high
temperatures, the theaflavins in the solution are converted to thearubigins and
carbohydrates caramelize.
• Plate heat exchangers can cause the desired evaporation at around 45oC, with short
residence times that reduce the risk of thermal damage.

9. Manufacturing process of instant tea
Blending
• Concentrated tea liquor is blended with previously stripped aroma
compounds before drying.
Drying
• Drum, spray and freeze drying can be used for the drying of concentrated
tea liquor, but spray drying is most commonly used in the industry because
it is cheaper in terms of both capital and running costs.
• In a spray dryer, concentrated solution should be fed into the drying tower
by high pressure homogenizing pump and then sprayed in the form of fine
droplet dispersion into a current of heated air. Air and solids may move in
parallel or counter flow.
• Drying occurs very rapidly, so that this process is very useful for materials
that are damaged by exposure to heat for higher time. The dry product will
be collected at the bottom of the spray dryer, and fines to be collected in
the cyclones.

11. References
• Unit Operations in Food Processing - R. L. Earle www.nzifst.org.nz/unitoperations/
• Pandey R.K and Manimehalai N, Production of Instant Tea Powder by Spray Drying. International
Journal of Agriculture and Food Science Technology, volume 5, number 3 (2014), pp. 197-202
• https://www.flottweg.com/product-lines/decanter/
• http://www.jlspray.com/product/444-instant-black-tea-production-line--852c/
• http://www.gea.com/
• www.sspindia.com