The Journey: Tree to the Cup

Processing the leaf

In tea manufacturing, the leaf goes through some or all of the stages of withering, rolling, fermentation, and drying. The process has a twofold purpose:

(1) to dry the leaf and

(2) to allow the chemical constituents of the leaf to produce the quality peculiar to each type of tea.

The best-known constituent of tea is caffeine, which gives the beverage its stimulating character but contributes only a little to colour, flavour, and aroma. About 4% of the solids in fresh leaf is caffeine, and one teacup of the beverage contains 60 to 90 milligrams of caffeine. The most important chemicals in tea are the tannins, or polyphenols, which are colourless, bitter-tasting substances that give the drink its astringency. When acted upon by an enzyme called polyphenol oxidase, polyphenols acquire a reddish colour and form the flavouring compounds of the beverage. Certain volatile oils contribute to the aroma of tea, and also contributing to beverage quality are various sugars and amino acids.
Only black tea goes through all stages of the manufacturing process. Green tea and oolong acquire their qualities through variations in the crucial fermentation stage.

Black tea

WITHERING
Plucking the leaf initiates the withering stage, in which the leaf becomes flaccid and loses water until, from a fresh moisture content of 70 to 80 percent by weight, it arrives at a withered content of 55 to 70 percent, depending upon the type of processing.
In the traditional process, fresh leaf is spread by hand in thin layers onto trays or sections of coarse fabric called tats. It is then allowed to wither for 18 to 20 hours, depending upon several factors that include the temperature and humidity of the air and the size and moisture content of the leaf. Withering in the open air has been replaced by various mechanized systems. In trough withering, air is forced through a thick layer of leaf on a mesh in a trough. In drum withering, rotating, perforated drums are used instead of troughs, and in tunnel withering, leaf is spread on tats carried by mobile trolleys and is subjected to hot-air blasts in a tunnel. Continuous withering machines move the leaf on conveyor belts and subject it to hot air in an enclosed chamber, discharging withered leaf while fresh leaf is simultaneously loaded.
Mechanized systems greatly reduce withering time, but they can also lower the quality of the final product by reducing the time for chemical withering, during which proteins and carbohydrates break down into simpler amino acids and sugars, and the concentration of caffeine and polyphenols increases.

ROLLING
At this stage, the withered leaf is distorted, acquiring the distinctive twist of the finished tea leaf, and leaf cells are burst, resulting in the mixing of enzymes with polyphenols.
The traditional method is to roll bunches of leaves between the hands, or by hand on a table, until the leaf is twisted, evenly coated with juices, and finally broken into pieces. Rolling machines consist of a circular table fitted in the centre with a cone and across the surface with slats called battens. A jacket, or bottomless circular box with a pressure cap, stands atop the table. Table and jacket rotate eccentrically in opposite directions, and the leaf placed in the jacket is twisted and rolled over the cone and battens in a fashion similar to hand rolling. Lumps of rolled leaf are then broken up and sifted. The smaller leaf passing through the sieve—called the fines—is transferred to the fermentation room, and the remaining coarse leaf is rolled again.

In many countries, rolling the leaf has been abandoned in favour of distortion by a variety of machines. In the Legg cutter (actually a tobacco-cutting machine), the leaf is forced through an aperture and cut into strips. The crushing, tearing, and curling (CTC) machine consists of two serrated metal rollers, placed close together and revolving at unequal speeds, which cut, tear, and twist the leaf. The Rotorvane consists of a horizontal barrel with a feed hopper at one end and a perforated plate at the other. Forced through the barrel by a screw-type rotating shaft fitted with vanes at the centre, the leaf is distorted by resistor plates on the inner surface of the barrel and is cut at the end plate. The nontraditional distorting machines can burst leaf cells so thoroughly that in many cases they render the withering stage unnecessary. However, unlike traditional rolling, they do not produce the larger leafy grades of tea.

FERMENTATION
Fermentation commences when leaf cells are broken during rolling and continues when the rolled leaf is spread on tables or perforated aluminium trays under controlled conditions of temperature, humidity, and aeration. The process actually is not fermentation at all but a series of chemical reactions. The most important is the oxidation by polyphenol oxidase of some polyphenols into compounds that combine with other polyphenols to form orange-red compounds called theaflavins. The theaflavins react with more units to form the thearubigins, which are responsible for the transformation of the leaf to a dark brown or coppery colour. The thearubigins also react with amino acids and sugars to form flavour compounds that may be partly lost if fermentation is prolonged. In general, theaflavin is associated with the brightness and brisk taste of brewed tea, while thearubigin is associated with strength and colour.
In traditional processing, optimum fermentation is reached after two to four hours. This time can be halved in fermenting leaf broken by the Legg cutter, CTC machine, and Rotorvane. In skip fermentation, the leaf is spread in aluminum skips, or boxes, with screened bottoms. Larger boxes are used in trough fermentation, and in continuous fermentation the leaf is spread on trays on a conveyor system. In all of these fermentation systems the leaf is aerated by forced air (oxygen being necessary for the action of the enzymes), and it is brought by automated conveyor to the dryer.

DRYING
At this stage, heat inactivates the polyphenol enzymes and dries the leaf to a moisture content of about 3 percent. It also caramelizes sugars, thereby adding flavours to the finished product, and imparts the black colour associated with fermented tea.
Traditionally, fermented leaf was dried on large pans or screens over fire, but since the late 19th century, heated forced air has been used. A mechanized drier consists of a large chamber into the bottom of which hot air is blown as the leaf is fed from the top on a series of descending conveyors. The dried leaf is then cooled quickly to prevent overdrying and loss of quality. Modern innovations on the drier are the hot-feed drier, where hot air is supplied separately to the feeder to arrest fermentation immediately as the leaf is fed, and the fluid-bed drier, where the leaf moves from one end of the chamber to the other over a perforated plate in a liquid fashion.

Green tea

In preparing unfermented tea, the oxidizing enzymes are killed by steamblasting the freshly plucked leaf in perforated drums or by roasting it in hot iron pans prior to rolling. The leaf is then subjected to further heating and rolling until it turns dark green and takes a bluish tint. The leaves are finally dried to a moisture content of 3 to 4 percent and are either crushed into small pieces or ground to a powder.

With the inactivation of polyphenol oxidase, the polyphenols are not oxidized and therefore remain colourless, allowing the processed leaf to remain green. The absence of theaflavins and thearubigins in the finished leaf also gives the beverage a weaker flavour than black tea.

Oolong tea

After a brief withering stage, the leaf is lightly rolled by hand until it becomes red and fragrant. For oolong it is then fermented for about one-half, and for pouchong for one-quarter, of the time allowed for black tea. Fermentation is stopped by heating in iron pans, and the leaf is subjected to more rolling and heating until it is dried.

Packaging

Sorting and grading

The first step in packaging tea is grading it by particle size, shape, and cleanliness. This is carried out on mechanical sieves or sifters fitted with meshes of appropriate size. With small-sized teas in demand, some processed teas are broken or cut again at this stage to get a higher proportion of broken grades. Undesirable particles, such as pieces of tough stalk and fibre, are removed by hand or by mechanical extractor. Winnowing by air removes dust, fibres, and fluff.

Packing

Teas are packed in airtight containers in order to prevent absorption of moisture, which is the principal cause of loss of flavour during storage. Packing chests are usually constructed of plywood, lined with aluminum foil and paper, and sealed with the same material. Also used are corrugated cardboard boxes lined with aluminum foil and paper or paper sacks lined with plastic.

Blended tea
Blended teas are sold to consumers as loose tea, which is packed in corrugated paper cartons lined with aluminum foil, in metal tins, and in fancy packs such as metallized plastic sachets, or they are sold in tea bags made of special porous paper. Tea bags are mainly packed with broken-grade teas.

Instant 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 temperatures are used to minimize loss of flavour and aroma. Instant green teas are produced by similar methods, but hot water is used to extract liquor from powdered leaves. Because all instant teas absorb moisture, they are stored in airtight containers or bottles.

Preparing the beverage

Blending

Tea sold to the consumer is a blend of as many as 20 to 40 teas of different characteristics, from a variety of estates, and from more than one country. Price is an important factor, with cheap teas (called fillers) used to round off a blend and balance cost. Blends are often designed to be of good average character without outstanding quality, but distinctive blends—for example, with a flavour of seasonal Ceylon tea or the pungency and strength of Assam tea—are also made.

Brewing

A tea infusion is best made by pouring water just brought to the boil over dry tea in a warm teapot and steeping it from three to five minutes. The liquor is separated from the spent leaves and may be flavoured with milk, sugar, or lemon.

Tasting

Professional tasters, sampling tea for the trade, taste but do not consume a light brew in which the liquor is separated from the leaf after five to six minutes. The appearance of both the dry and infused leaf is observed, and the aroma of vapour, colour of liquor, and creaming action (formation of solids when cooled) are assessed. Finally the liquor is taken into the mouth with a sucking noise, swirled around the tongue, brought into contact with the palate, cheek, and gums, and then drawn to the back of the mouth and up to the olfactory nerve in the nose before being expectorated. The liquor is thus felt, tasted, and smelled. Tasters have a large glossary of terms for the evaluation of tea, but the less-demanding consumer drinks it as a thirst quencher and stimulant and for its distinctive sour-harsh taste.

Classification of teas

By country of origin

Teas are classified according to region of origin

  • China
  • Ceylon
  • Japanese
  • Indonesian
  • Taiwan
  • African

By region

India

Darjeeling
Regarded as the “Champagne of Teas,” Darjeeling is grown on 100 estates on the foothills of the Himalayas, on over 18,000 hectares at about 7000 ft.
Light and delicate in flavour and aroma, and with undertones of muscatel, Darjeeling is an ideal complement to dinner or afternoon tea. The first “flushes” (pluckings) are thought to produce the best Darjeeling vintage but all crops are of very high quality. Darjeeling Green is rare tea similar to Japanese Sencha with an exquisite aroma and delicate taste.

First Flush (Castleton, Bloomfield)
The Darjeeling bushes’ first new shoots – the first flush – are picked in April. These first teas of the season are the finest and are much in demand, fetching incredibly high prices at auction. Has a perfect green-brown leaf with a subtle astringent flavour.
Second Flush (Puttabong, Namring)
Second flush Darjeelings are picked between May and June and produce excellent quality teas that are considered by some to be better than the first flush as they have a fruitier, less astringent flavour than the earlier teas. The leaves are darker brown and contain plenty of silvery tip.

Assam
Assam is a major growing area covering the Brahmaputra valley, stretching from the Himalayas down to the Bay of Bengal. Assam tea has distinctive flecked brown and gold leaves known as “orange” when dried. In flavour it is robust, bright with a smooth, malt pungency and is perfect as the first cup of tea of the day. Such teas are used in everyday popular blends because of the full-bodied richness. There is also an Assam Green tea with an unusual light, almost sweet liquor.

First Flush (Bamonpookri)
Assam tea bushes start growing in March and the first flush is picked for 8 to 10 weeks, first flush Assams e.g. Bamonpookri, an excellent quality tea with a strong fresh flavour; are rarely marketed in the Europe
Second Flush (Napuk)
The plucking of the second flush begins in June with most of the production taking place from July to September. The second flush Assam is the best of the season and when brewed give a rich aroma, a clear dark read liquor and a strong malty taste.

Nilgris (Nunsch)
The Nilgiri region, situated in southern India, forms a high hilly plateau at the conjunction of the Eastern and Western Ghat mountains. Most Nilgiri teas are used for blending, but there is a rapidly growing demand for the speciality tea of the area. Nilgiri has a bright amber colour and a refreshing, bright and delicate taste.

Ceylon

Kandy
Tea of the Kandy region is described as ‘mid-grown’, the altitude of cultivation ranging between 650m and 1,300m (2,000-4,000ft). Nilambe, Hantane, Pussellawa, Gampola and, Hewaheta.
The region produces a broad range of strengths and styles: estates at lower elevations produce a larger leaf with gives a stronger-flavoured beverage, while those higher up grow a smaller leaf that yields a more subtle and delicate flavour.
Region’s best tea is produced during the first quarter of the year, when cool, dry weather sets in across the district.
Kandy teas tend to produce a relatively bright infusion with a coppery tone. Though lighter in the cup, they present a good deal of strength and body (flavoursome).
Estates at lower elevations produce a larger leaf with gives a stronger-flavoured beverage, while those higher up grow a smaller leaf that yields a more subtle and delicate flavour.

Nuwara Eliya
Tea of the Nuwara Eliya region is described as ‘high-grown’, the altitude of cultivation is over 4,000ft. Nuwara Eliya tea enjoys two ‘quality seasons’, the eastern as well as the western. The balance between the two climatic systems varies from estate to estate.
High altitude and year-round low temperatures produce a very slow-growing bush with unusually small leaves that take on an orange hue – just a hint against the blackness – after withering. The infused leaf acquires a greenish-yellow tone, and the infusion in the cup is the palest among all the regional varieties of Ceylon Tea, with a subtle golden hue and a delicate yet fragrant bouquet.

Uda Pussellawa

Uva

Dimbula

Sabaragamuwa

Ruhuna

China

  • Black Teas – Lapsang Souchong
  • Black Teas – Keemun from Chi-men (Anhwei Province)
  • Black Teas – Yunnan
  • Green Teas – Gunpowder
  • Green Teas – Chun Mee
  • Green Teas – Oolong
  • Green Teas – Tie Kuan Yin
  • Green Teas – Pouchong
  • White Teas – Pai Mu Tan Imperial
  • White Teas – Yin Zhen
  • Puerh Tea
  • Compressed Teas – Tuancha
  • Compressed Teas – Tuocha
  • Flavoured and Scented Teas – Jasmine
  • Flavoured and Scented Teas – Rose Congou
  • Flavoured and Scented Teas – Earl Grey
  • Flavoured and Scented Teas – Osmanthus
  • Flavoured and Scented Teas – Magnolia
  • Flavoured and Scented Teas – Orchid
  • Flavoured and Scented Teas – Chloranthus
  • Flavoured and Scented Teas – Lichee

Japan

  • Enshu
  • Sencha
  • Gyokuro

By the size of the processed leaf

Teas are also classified by the size of the processed leaf: Traditional operations result in larger leafy grades and smaller broken grades.

The leafy grades

Leafy grades come mainly from the tougher and mature leaves.

  • Flowery Pekoe (FP)
  • Orange Pekoe (OP)
  • Pekoe (P)
  • Pekoe Souchong (PS)
  • Souchong (S)

Whole leaf grades

The grades for whole leaf orthodox black tea are: Ceylon orange pekoe (OP) grades’

  • OP1—slightly delicate, long, wiry leaf with the light liquor
  • OPA—bold, long leaf tea which ranges from tightly wound to almost open
  • OP—main grade, in the middle between OP1 and OPA, can consist of long wiry leaf without tips
  • OP Superior—primarily from Indonesia, similar to OP
  • Flowery OP—high-quality tea with a long leaf and few tips, considered the second grade in Assam, Dooars, and Bangladesh teas, but the first grade in China
  • F OP1—as above, but with only the highest quality leaves in the FOP classification
  • Golden Flowery OP1—higher proportion of tip than FOP top grade in Milima and Marinyn regions, uncommon in Assam and Darjeeling
  • Tippy Golden F OP—the highest proportion of tip, main grade in Darjeeling and Assam
  • TGF OP1—as above, but with only the highest quality leaves in the TGFOP classification
  • Finest TGF OP—highest quality grade (Note: “Special” is occasionally substituted for “Finest”, with a number 1 at the end to indicate the very finest), often hand processed and produced at only the best plantations, roughly one quarter tips
  • SFTGFOP(1)—sometimes used to indicate the very finest

Broken grades

Broken grades usually have substantial contributions from the more tender shoots. In modern commercial grading, 95 to 100 percent of production belongs to broken grades, whereas earlier a substantial quantity of leafy grades was produced. This shift has been caused by an increased demand for teas of smaller particle size, which produce a quick, strong brew.

  • Broken Orange Pekoe (BOP)
  • Broken Pekoe (BP)
  • BOP Fanning
  • Fannings
  • Dust

Broken leaf grades

  • BT—Broken Tea: Usually a black, open, fleshy leaf that is very bulky. Classification used in Sumatra, Sri Lanka, and some parts of Southern India.
  • BP—Broken Pekoe: Most common broken pekoe grade. From Indonesia, Ceylon, Assam and Southern India.
  • BPS—Broken Pekoe Souchong: Term for broken pekoe in Assam and Darjeeling.
  • FP—Flowery Pekoe: High-quality pekoe. Usually coarser with a fleshier, broken leaf. Produced in Ceylon and Southern India, as well as in some parts of Kenya.
  • BOP—Broken Orange Pekoe: Main broken grade. Prevalent in Assam, Ceylon, Southern India, Java, and China.
  • F BOP—Flowery Broken Orange Pekoe: Coarser and broken with some tips. From Assam, Ceylon, Indonesia, China, and Bangladesh. In South America coarser, black broken.
  • F BOP F—Finest Broken Orange Pekoe Flowery: The finest broken orange pekoe. Higher proportion of tips. Mainly from Ceylon’s “low districts”.
  • G BOP—Golden Broken Orange Pekoe: Second grade tea with uneven leaves and few tips.
  • GF BOP1—Golden Flowery Broken Orange Pekoe 1: As above, but with only the highest quality leaves in the GFBOP classification.
  • TGF BOP1—Tippy Golden Flowery Broken Orange Pekoe 1: High-quality leaves with a high proportion of tips. Finest broken First Grade Leaves in Darjeeling and some parts of Assam.

Fannings grades

  • PF—Pekoe Fannings
  • OF—Orange Fannings: From Northern India and some parts of Africa and South America.
  • FOF—Flowery Orange Fannings: Common in Assam, Dooars, and Bangladesh. Some leaf sizes come close to the smaller broken grades.
  • GFOF—Golden Flowery Orange Fannings: Finest grade in Darjeeling for tea bag production.
  • TGFOF—Tippy Golden Flowery Orange Fannings.
  • BOPF—Broken Orange Pekoe Fannings: Main grade in Ceylon, Indonesia, Southern India, Kenya, Mozambique, Bangladesh, and China. Black-leaf tea with few added ingredients, uniform particle size, and no tips.

Dust grades

  • D1—Dust 1: From Sri Lanka, Indonesia, China, Africa, South America, and Southern India.
  • PD—Pekoe Dust
  • PD1—Pekoe Dust 1: Mainly produced in India.

Other terms

  • Musc.—Muscatel
  • Cl.—Clonal
  • Ch.—China varietal
  • Qu.—Queen jat
  • FBOPF Ex. Spl.—Flowery Broken Orange Pekoe Fannings (Extra Special)
  • FP—(Flowery Pekoe)
  • PS—Pekoe Souchong
  • S—Souchong
  • BOF—Broken Orange Fannings
  • BPF—Broken Pekoe Fannings
  • RD—Pekoe Dust/Red Dust
  • FD—Fine Dust
  • GD—Golden Dust
  • SRD—Super Red Dust
  • SFD—Super Fine Dust
  • BMF—Broken Mixed Fannings

By the manufacturing process

This is the most important classification, resulting in the three categories:

  • Fermented (black) Black tea, by far the most common type produced, is best made from Assam or hybrid plants. The infused leaf is bright red or copper coloured, and the liquor is bright red and slightly astringent but not bitter, bearing the characteristic aroma of tea.
  • Unfermented (green) Green tea is usually produced from the China plant and is grown mostly in Japan, China, and to some extent Malaysia and Indonesia. The infused leaf is green, and the liquor is mild, pale green or lemon-yellow, and slightly bitter.
  • Semi-fermented (oolong or pouchong) Oolong and pouchong teas are produced mostly in southern China and Taiwan from a special variety of the China plant. The liquor is pale or yellow in colour, as in green tea, and has a unique malty, or smoky, flavour.

References

Tea, Buzzle.com, http://www.buzzle.com/articles/tea/
Tea, Alltea.com, http://www.alltea.com/blog/2012/02/tea-facts
The Tea Man’s Tea Talk, Tea Talk, http://www.teatalk.com/ Tea, Wikipedia, http://en.wikipedia.org/wiki/Tea

History of the tea trade

According to legend tea has been known in China since about 2700 BC. For millennia it was a medicinal beverage obtained by boiling fresh leaves in water, but around the 3rd century AD it became a daily drink, and tea cultivation and processing began. The first published account of methods of planting, processing, and drinking came in AD 350. Around 800 the first seeds were brought to Japan, where cultivation became established by the 13th century.

Chinese from Amoy brought tea cultivation to the island of Formosa (Taiwan) in 1810. Tea cultivation in Java began under the Dutch, who brought seeds from Japan in 1826 and seeds, workers, and implements from China in 1833. In 1824 tea plants were discovered in the hills along the frontier between Burma and the Indian state of Assam. The British introduced tea culture into India in 1836 and into Ceylon (Sri Lanka) in 1867. At first they used seeds from China, but later seeds from the Assam plant were used.

The Dutch East India Company carried the first consignment of China tea to Europe in 1610. In 1669 the English East India Company brought China tea from ports in Java to the London market. Later, teas grown on British estates in India and Ceylon reached Mincing Lane, the centre of the tea trade in London. By the late 19th and early 20th centuries, tea growing had spread to Russian Georgia, Sumatra, and Iran and extended to non-Asian countries such as Natal, Malaŵi, Uganda, Kenya, Congo, Tanzania, and Mozambique in Africa, to Argentina, Brazil, and Peru in South America, and to Queensland in Australia.

References

History of Tea, Quatr.us answers questions, http://quatr.us/food/tea.htm