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KERALA AGRICULTURAL UNIVERSITY
KELAPPAJI COLLEGE OF AGRICULTURAL ENGINEERING & TECHNOLOGY
Types of tea..................................................................................... 7
Instant tea........................................................................................ 9
Components of tea........................................................................... 9
Equipments used in tea processing.................................................... 10
Common grades of tea....................................................................... 12
By product utilisation of tea.............................................................. 12
Health benefits of tea......................................................................... 14
Case studies....................................................................................... 15
Tea is one of the true stimulants and satisfying the palate demands of human
beings for centuries. Teas can generally be divided into categories based on how they are
processed. There are at least six different types of tea: white, yellow, green, oolong (or
wulong), black (called red tea in China), and post-fermented tea. Tea contains a large number
of possibly bioactive chemicals, including flavonoids; amino acids, vitamins, caffeine and
several polysaccharides, and a variety of health effects have been proposed and investigated.
Tea has wide applications so it processed in many ways so as to get different products.
Second to water, Tea is the most commonly consumed beverage in
the world. People drink more tea than coffee, soft drinks, dairy products, and alcohol
combined. India is the world's largest tea grower and produces some of the best teas on the
planet. Ineeka's family-owned organic tea estates are located in two of India's best tea
producing regions - Darjeeling and Assam - both prized for their unique teas. The importance
of tea in the world economy cannot be overstated. It is one of the most valuable primary
products in world trade. It is one of the true stimulants and has been satisfying the palate
demands of human beings for centuries and also the oldest known and is now the most
The tea plant and tea drinking habits were exclusively Chinese initially, but there tea drinking
has undergone changes to suit the styles and requirements of countries of its later adoption.
Different techniques are used for the processing coupled with consumer acceptance have led
to the development of a wide variety of tea which appearance, colour, briskness, aroma etc to
satisfy every consumer taste within and outside the country of origin.
The history of tea in India spans more than 160 years. The rapid expansion of cultivation in
Assam followed by the establishment of plantations in Darjeeling, Teerai and the Dooars
regions of northern Bengal, and the Nilgiris and other regions of southern India. The global
production of tea is to be around 2.78 billion kg; about 3 billion cups of tea are consumed
daily world wide.India, Srilanka and China together account for about 60% of the global
production of tea.
Scientific name :Camellia sinensis.
Family : Camelliaceae.
Camellia Sinensis, an ever green shrub that grow to height of 30 feet, but is usually
clipped to a height of2-5 feet in cultivation for easy plucking purposes. Harvest of its leaves
is by hand with special shears, or by machines. It is cultivated as a plantation crop, like acidic
soil and a warm climate with at least 50 inches of rain per annum.tea from individual
plantations has developed its own character and taste, depending on the direction of the
growing slopes and weather conditions at the time of plucking leaf and manufacture from
green leaf to black tea. Tea breaks down into three basic types: black green and oolong.
It is a method in which the leaves and flushes from camellia sinensis are transferred in to the
dried leaves for brewing tea. The types of tea are distinguished by the processing they
undergo. In its most general form, tea processing involves oxidising the leaves, stopping the
oxidation, forming the tea and drying it. Of these steps, the degree of oxidation plays a
significant role of determining the final flavour of the tea, with curing and leaf breakage
contributing to flavour by a lesser amount. Although each type of tea has different taste,
smell and visual appearance, tea processing for all tea types consists of a very similar set of
methods with only minor variations:
Picking is done by hand when a higher quality tea is needed. Hand picking is done by pulling
the flush with a snap of the wrist and does not involve twisting or pinching the flush, since
doing the latter reduces the quality of the leaves tea flushes and leaves can also be picked by
machine, though there will be more broken leaves and partial flushes.
Withering is used to remove excess water from the leaves and allows a very slight amount of
oxidation. The leaves can be either put under the sun or left in a cool breezy room to pull
moisture out from the leaves.
In order to promote and quicken oxidation, the leaves may be may be bruised by tumbling by
baskets or by being kneaded or by being kneaded or rolled over by heavy wheels. This also
releases some of the leaf juices, which may aid in oxidation and change the taste profile of
Fermentation is the most important stage in the manufacture tea. For this the
leaves are left on their own climate controlled room where they turn progressively darker. In
this process the chlorophyll in the leaves is enzymatically broken down, and its tannins are
released or transformed. This process is termed to as fermentation. The tea producer may
choose when the oxidation should be stopped, which depends on the desire qualities in the
final tea as well as the weather conditions. For light oolong teas this may be anywhere from
5-40% oxidation, in darker oolong teas 60-70% and in black teas 100%. The mechanical
aspect involves spreading out of the leaves macerated by rolling a layer 5-8 cms thick, for 45
minutes to 3 hours, depending on the quality of the leaves. Fermenting machines make the
process continuous, that is, every unit of macerated leaf has to be spread out for individual
This is done to stop the leaf oxidation at a oxidation at a desired level. This is followed by
moderatively heating the tea leaves, thus deactivating their oxidative enzymes, without
destroying the flavour of the tea.
After fermentation the tea is dried by passing through a drier .the objective of drying is to a)
arrest fermentation b) remove moisture and produce teas with good qualities. The mass of
leaf is exposed to hot air when it passes through a chamber is maintained at temperatures
between 100-130C centigrade as its base range. It takes 15 minutes to half an hour to dry the
leaf, when the enzymes are fully inactivated. After completion of the drying process the tea
becomes fully black in colour.
Tea is a markedly hygrospic material and while cooling and sorting it absorbs moisture.
Before packing tea the accumated series of daily batches of each grade are bulked and mixed
to obtain the highest possible degree of unity. Before packing tea is passed under powerful
magnets to prevent possible pieces of iron mixing with the tea. Packing is the process of
preserving the product using the cheapest but most appropriate material taking in to account
the product properties.
Types of tea
1. Green tea
Green tea is made from the leaves from Camellia sinensis that have undergone minimal
oxidation during processing. . Green tea has become the raw material for extracts used in
various beverages, health foods, dietary supplements, and cosmetic items. Many varieties of
green tea have been created in the countries where it is grown. These varieties can differ
substantially due to variable growing conditions, horticulture, production processing, and
harvesting time. The main constituent of green tea leaves belong to the polyphenol group
accounting for 25-35% on a dry basis.
Processing of green tea
Steaming (for to inactivate the enzyme)
2. Oolong tea
The processing of oolong tea requires only a partial oxidation of the leaves. After the leaves
are plucked, they are laid out to wither for about 8 to 24 hours. Then the leaves are tossed in
baskets in order to bruise the edges of the leaves. This bruising only causes the leaves to
partially oxidize because only a portion of the enzymes are exposed to air. The taste of the tea
is very rich. It can be sweet and fruity, or woody and thick, or green and fresh, all depends on
the horticulture and style of production. Here only 50% fermentation is done.
Processing of oolong tea
3. Black tea
Black tea is a type of tea that is more oxidized than oolong, green and white teas. Black tea is
generally stronger in flavour than the less oxidized teas. Black tea retains its flavour for
several years. Here 100% fermentation is done.
Processing of black tea
Instant teas are produced from black tea by extracting the liquor from processed leaves, tea
wastes, or undried fermented leaves, concentrating the extract under low pressure, and drying
the concentrate to a powder by freeze-drying, spray-drying, or vacuum-drying. Low
temperature used to minimize loss of flavour and aroma.
Processing of instant tea
Components of tea
Tannins are a class of compounds in tea, especially black tea, which tend to have a bitter
flavour and astringent properties. Teas high in tannins can be described as tannic. Tannins are
naturally occurring and common, and are an important component of red wine. They are also
responsible for the dark colour in some streams, as they are found in leaves and wood, and
are released as organic matter breaks down.
2. Phenolic compound
The phenolic content in tea refers to the phenols and polyphenols, natural plant compounds
which are found in tea. These chemical compounds affect the flavour and mouth feel and are
speculated to provide potential health benefits.
3. Amino acids
Aspartic, glutamic, serine, glutamine, tyrosine, valine, phenylalanine, leucine, isoleucine and
thiamine were found to be the principal amino acids present in tea leaf.Theanine alone
contributed around 60% of total amino acid content. The amino acid plays an important role
in the development of tea aroma during the processing of black tea.
Caffeine is a purine derivative, which is 1, 3, 7-tri-methl xanthine.it has stimulating property
and removes mental fatigue. The contribution of caffeine to the infusion is the briskness and
creamy property resulting from the complex formed by caffeine with polypenols.
The four major carotenoids,β-carotene,lutein,violaxanthine and neoxanthine .all these
carotids were found to decrease appreciably during black tea manufacture.
The free sugars found in tea shoot are glucose, fructose, sucrose, raffinose and stachyose.
Equipments used in tea processing
1. CTC machine
Crush, Tear, and Curl (also Cut, Twist, Curl) is a method of processing black tea,
Instead of the leaves being rolled as a final stage, they are passed through a series of
cylindrical rollers with hundreds of small sharps “teeth” that crush, tear, and curl the tea.CTC
was invented by William McKercher .CTC teas generally produce a rich red-brown colour
when they are boiled by the Indian method. The drawback of the CTC method is that it tends
by its nature, and unfortunately by adulteration, to homogenize all black tea 11flavours. In
the process of crushing, tearing and pelletizing the tea leaves, large pressures and stresses
occur which break down the cells, releasing large amounts of the phytins that normally
oxidize to produce black tea’s mahogany colour. Since, regardless of origin, CTC teas in their
dry form are generically “tea-like” in aroma, very similar in pelletized form, it is very easy to
adulterate a more expensive CTC-type tea with inexpensive and generally mild lowland teas
of the same process. Whole and broken leaf teas by contrast are quite varied in appearance,
making adulteration more difficult.
Fig: CTC machine.
2. Orthodox machine
The term orthodox is used by the tea industry to designate methods that adhere to traditional
production guidelines. Orthodox processing calls for a wither of 18-24 hours, two to six
rolling of one half-hour each, and a fermentation of 3-4 hours. There are also specifications
for firing and drying.
Fig: orthodox machine.
Primary objectives are;
1. To repture the cell walls and exposes their contents.
2. To bring the contents of tea leaf cells in contact of air to start the process of oxidation
3. To break the larger twisted leaf in to smaller particles
Common grades of tea
All tea is graded according to leaf size. One of the most common terms is ‘Orange
Pekoe’, and is often mistaken for a type of tea. In actual fact it is a term that denotes a
particular size of Black Leaf Tea. Grading is not related to its quality, that’s down to the
climate, location and the type of processing. It is the leaf size that plays an important role in
influencing the overall essence of a cup.
White Tea, Green Tea and Oolong Tea are generally not graded like most Black Teas. Here
are the most common grades for black tea leaves.
F.O.P. Flowery Orange Pekoe - Refers to high quality whole leaf tea made from the
first two leaves and bud of the shoot. India produces large amounts of this grade.
G.F.O.P. Golden Flowery Orange Pekoe - The golden refers to the colourful tips at
the end of the top bud.
T.G.F.O.P. Tippy Golden Flowery Orange Pekoe - FOP with larger amount of tips
F.T.G.F.O.P Finest Tippy Golden Flowery Orange Pekoe - An even higher quality
with more tips than FOP
O.P. Orange Pekoe: Refers to a high quality thin, wiry leaf rolled more tightly than
F.O.P. Picked later in the year than F.O.P.
S. Souchong - A twisted leaf picked from the bottom of the tea bush. China produces
this grade used in their Smokey teas.
By products utilisation of tea
1. Clean carpets
2. Clean antique rugs:
3. Shine wood floors: The tannins in black tea can help shine and colour hardwood flooring.
Follow your regular floor cleaning routine by carefully rubbing some brewed tea into the
floor (don’t use too much water on hardwood flooring) and letting it air dry.
4. Polish furniture: Brewed tea also can help clean and shine wood furniture. Dip a soft
cloth in a small amount of tea, and use it to wipe down the tables, chairs and more.
5. Clean mirrors and windows: Tea can remove stubborn, greasy fingerprints from glass,
and make it sparkle. Simply rub a damp teabag on the glass or fill a spray bottle with brewed
6. Clean toilet stains: Rumour has it that used tea bags can magically remove stubborn stains
in the bottom of the toilet bowl. Just leave them in the toilet for several hours, then flush the
toilet and brush the bowl.
7. Get rid of fishy smells: Rinse your hands with tea after eating or preparing fish (or other
stinky foods) to eliminate odours.
8. De-stink fridges: Instead of baking soda (or maybe in addition), try used tea bags in the
fridge to absorb odours.
12. Clean the fireplace: Sprinkling wet tealeaves on fireplace ashes while scooping them out
may help reduce blowing dust.
14. Make a car air freshener: Likewise, you can freshen up the car without a chemical-
laden commercial air freshener. Put lavender tea or other soothing herbal tea in a bag under
the seat to fight odors.
15. Soothe sunburn: Wet teabags can soothe sunburns and other minor burns. For full-body
sunburn, soak in a tea bath.
16. Soothe tired eyes: Warm, wet teabags can reduce puffiness and soothe pain around tired
eyes — and teabags on your eyes look a little less ridiculous than cucumber slices.
18. Soothe razor burn: A wet tea bag can also reduce and soothe razor burn.
19. Drain boils: Cover a boil with wet tea bag overnight, and it should drain painlessly.
21. Dry poison ivy rash Dry a weepy poison ivy rash with strongly brewed tea. Simply dip a
Cotton ball into the tea, dab it on the affected area, and let it air-dry. Repeat as needed.
22. Save a broken fingernail: To salvage a partially broken fingernail, use a piece of mesh
tea bag to create a splint of sorts between the nail and the broken piece. Coat in nail polish.
23. Make soap: Tea is a useful addition when making glycerine soap. The texture and scent
can help make the soap smell and cleanse better.
24. Help recover from injections: A wet teabag on an injection site can be soothing, for
babies or adults.
25. Soothe bleeding gums: For an older child who loses a tooth, try putting a cold, wet
teabag in the mouth where the tooth was lost. It can reduce bleeding and soothe pain.
26. Make mouthwash: Similarly, toothaches and other mouth pain can be soothed with a
rinse of antiseptic peppermint tea mixed with a little salt.
27. Shine dry hair: Brewed tea makes a good conditioner for dry hair. Rinse with
(unsweetened) tea and leave to dry for a while, and then rinse again with water.
28. Dye hair: Brewed tea also is a good natural hair dye. Mix rosemary and sage into dark
black tea and let the mixture stand overnight. Strain the mix and thoroughly work it into your
hair. Repeat as needed for the desired colour.
29. Improve skin: To protect and beautify skin, try bathing in green tea. Another widely
recommended skin booster is chamomile tea in a facial steamer.
30. Cure acne: Some acne sufferers swear by washing their faces with green tea to cure or
reduce their acne.
33. Improve breath: Gargling with strong tea can help reduce halitosis.
35. Cure the common cold: The same Chinese traditionalists also swear by tea as a time-
tested remedy for many cold symptoms. Of course, others maintain that a cold will last seven
days with tea treatment, or one week without.
37. Tenderize meat: Marinate tough meat in black tea to make it more tender.
38. Smoke it: Add tea to a smoker to make tea-infused cheeses and meats.
39. Boil eggs: The Chinese also like to add tea leaves to the water after boiled eggs are
cooked. This adds some flavour and colour to the boiled eggs.
Health benefits of tea
Tea contains a large number of possibly bioactive chemicals, including
flavonoids; amino acids, vitamins, caffeine and several polysaccharides, and a variety of
health effects have been proposed and investigated.
1. Green and black tea may protect against cancer.
2. The catechins found in green tea are thought to be more effective in preventing certain
obesity-related cancers such as liver and colorectal cancer.
3. Green and black teas may protect against cardiovascular disease.
Case study: 1 Degradation pattern of gibberellic acid during the whole process of tea
By Hongping Chen; food chemistry; volume138, issue2-3; 1-july-2013, pages 976-981
The residues of gibberllic acid in tea shoots made tea, and tea infusion were determined by
ultra performance liquid chromatography tandem mass to study the degradation pattern
during tea planting, processing and brewing. The dissipation rate of gibberllic acid was
described using first order kinetics. Its half life ranged from 1.67 to 2.01 days in tea
processing had equally important functions.Gibberllicacid residues in product intermediates
and made tea. Except for water content, little gibberllicacid residue difference was found in
tea shoots and made tea.Gibberllicacid dissipated rapidly in baking stage during processing.
The transfer coefficient of gibberllicacid residues made from infusion was from 26.23%-
54.55%.gibberllicacid extraction efficiency varied from different infusion times and
concentrations of gibberllic acid in made tea. This research revealed that gibberllicacid may
be safe when applied in tea gardens at suitable doses and picking intervals
Case study: 2 Lipid occurrence, distribution and degradation to flavour volatiles during tea
By Ramaswamy Ravichandran; food chemistry, volume 68, issue1 january2000; pages7-13
The contents of neutral lipid, glycolipid and phospholipids and their fatty acid composition in
three cultivars (clones) and processed leaves at different stages of black tea manufacture were
measured. Glycolipids account for nearly 50% of the total lipids and are rich in linolenic acid.
Phospholipids were present in the least amount (15%) and had a high proportion of oleic,
linoleic and palmitic acids. Neutral lipids were found in moderate amounts (35%) and had a
high content of lauric, myristic, palmitic, stearic, oleic and linoleic acids. Well-marked clonal
variations in fatty acid composition of the lipid fractions were registered. With the maturation
of the tea shoot, the lipid content increased. Considerable losses of lipids/fatty acids were
observed in the withering process and again in the firing process. The other stages of
processing (rolling and fermentation) registered only a minor change in lipid/fatty acid
contents. Wide variation in lipid and flavour content was observed with season and a relation
was evolved between them. The reason for the superior flavour of orthodox teas over CTC
teas is explained on the basis of their lipid degradation. The changes in lipid content/fatty
acids were related to the volatiles produced.
1. K.C.Willson.1999.Crop production science in horticulture.CABI publishing, UK, 231p.
2. Hongping Chen.2013.Degradation pattern of gibberellic acid during the whole process of
tea production. Food chemistry .138: 976-981.
3. Ramaswamy Ravichandran.2000. Lipid occurrence, distribution and degradation to flavour
volatiles during tea processing. Food chemistry.68:7-13.
4. Dr.Balasubramaniam.1995.Tea processing. Academic press, Newyork.