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Công nghệ sản xuất trà túi lọc (tea bag)
Background
Tea has existed as a beverage since 2000 B.C. The brewing, serving, and
drinking of tea are time-honored rituals throughout the world. While there is
general agreement that the tea trade began in China, both China and India
lay claim to discovering the dietary properties of tea leaves. The Chinese tell
the story of a mythical emperor named Shen Nung who was so particular
about his nutrition that he boiled his drinking water before he drank it. One
day, the story goes, the wind caught some of the leaves on the tree branches
that he had used to build a fire. The leaves floated into his boiling water and,
lo, tea was created.

In India, the discovery is attributed to Bodhidharma, an actual person who
founded the Ch-an School of Buddhism. In A.D. 527, after four years of a
self-imposed nine-year meditation, Bodhidharma grew sleepy. In an attempt
to stay awake, he began to chew on the twigs of a nearby tree and suddenly
found himself wide awake; he had discovered tea.
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The tea bush is a white-flowered evergreen in the Camellia family. Chinese
documents record it as indigenous to the Hunan province in southwest
China. In modern times, it is generally accepted that the original tea bush
grew in India and was brought to China. It thrives in a rocky terrain. In
approximately A.D. 350, tea cultivation was also reported in the Szechwan
province along the Yangtze River.
During the T’ang Dynasty in the eighth century, tea drinking achieved the
status of an art form. Tea merchants hired a man named Lu Yu to compile
the first written record of Chinese tea ceremonies. Entitled Ch’a Ching (The
Class of Tea), the three-volume work revolutionized the tea industry. The

tea. In spite of the tariff, or perhaps because of it, a great deal of tea was
smuggled into the country. The tea tax also figured prominently in the
American Revolution, as witnessed by the infamous Boston Tea Party when
rebellious colonists pitched a shipment of East India Company tea into the
harbor.
Until the early 20th century, tea was sold loose. Tea bags were invented
quite by accident in 1904 when Thomas Sullivan, an enterprising merchant,
wrapped samples of tea leaves in silk bags and sent them to prospective
customers, some of whom dipped the bags directly into boiling water. The
silk bags gave way to gauze pouches and eventually to specially treated filter
paper.

Herb teas, caffeine-free and cultivated from a variety of plant leaves,
flowers, roots, bark, and seeds, have become enormously popular over the
last 20 years. Although they were probably brewed as early as prehistoric
times, herb teas were primarily consumed for medicinal purposes.
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Raw Materials
Tea bags are composed of two main ingredients: processed tea leaves and
filter-paper bags. The top tea leaves and leaf buds are hand-picked from the
plant. The leaves are then subjected to several processes including withering,
rolling, drying, cutting, and blending. The intensity and duration of each
process differs according to the type of tea.

The filter paper is made primarily of abaca, the leafstalk of Philippine
bananas also known as Manila hemp.
The Manufacturing Process
Withering
1 Traditional withering practices call for manually spreading the leaves in

brewing time.
Blending
5 The leaves are blended according to company recipes to achieve a uniform
taste and texture. Most teas are a blend of between 20-40 types of tea leaves.
The blending process may also include the addition of natural flavorings
such as cinnamon, orange peel, nutmeg, cloves, chocolate, licorice root,
peppermint, ginger, crushed hibiscus flowers, fennel seeds, and chicory root.
Measuring
6 The processed and blended tea leaves are stored in hoppers that hold up to
800 pounds (363 kg) of tea. Flow tubes connect each hopper to a doser
wheel. The doser wheel resembles a Ferris wheel with small chambers in the
place of seats. Air pushes the leaves through the flow tube and into the
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wheel which separates the tea into the chambers in pre-measured amounts,
usually two grams.
Tea bag assembly
7 Two large rolls of filter paper are fed over the top and underneath the
doser wheel. As each chamber arrives at the bottom of the doser wheel, it
releases the tea onto the bottom paper layer of paper as it moves along a
conveyer belt. The top layer of paper is lowered onto the lower layer so that
each measure of tea is sandwiched between the two layers.
8 A conveyer belt moves the three components to a heat-sealing drum fitted
with an indentation pattern. The drum quickly seals the paper along the
indentation lines. The timing of this process is closely monitored because
too much heat would adversely affect the tea.
9 The sealed paper continues along a conveyer belt until it reaches a
perforation blade that is calibrated to cut the paper into precise squares.
After a string and tag are stapled to the bag, they are dropped into pre-
printed boxes.