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Transcript of cafiene
Submitted By :- Sharu Sharma
Roll No.:-
Session :- 2010-2011
This is my duty to record my sincere thanks and deep sense
of gratitude to my respected teacher Mr. Surinder Sir in for
his valuable guidance, interest and constant encouragement
for the fulfillment of the project. I am highly obliged to our
lab teacher who provided me with the required apparatus and
chemicals.
CERTIFICATE
This is to certify that Sharu Sharma of class 12th of Army
Public School Janglot has successfully completed this
project.
Roll No. Class : 12th
Session 2010-11 Board: CBSE
CORRESPONDING TO SCHOOL
Roll No Class. 12th
Session 2010-2011
Candidate has done the experiment recorded in this project in
the lab and signature affixed on the recorded experiment are
genuine.
Teacher Incharge Principal
Determine the presence
of caffeine Present in
Different Samples of Tea
INTRODUCTION
Tea is the most
commonly and
widely used soft
beverage in the
household. It acts as
a stimulant for
central nervous system and skeleta l muscles. That is why
tea removes fatigue, tiredness and headache. It also
increases the capacity of thinking. It is also used for
lowering body temperature. The principal constituent of
tea, which is responsible for all these properties, is the
alkaloid-caffeine. The amount of caffeine in tea leavers
varies from sample to sample.
Originally it was thought that caffeine is responsible for
the taste and flavour of tea. But pure caffeine has been
found to be a tasteless while substance. Therefore, the taste
and flavour of tea is due to some other substance present
in it. There is a little doubt that the popularity of the
xanthenes beverages depends on their stimulant action,
although most people are unaware.
Determination of
Caffeine in Tea
Samples of any
stimulation.
The degree to
which an individual is stimulated by given amount of
caffeine varies from individual to individual.
For example, some people boast their ability to drink
several cups of coffee in evening and yet sleep like a long,
on the other hand there are people who are so sensitive to
caffeine that even a single cup of coffee will cause a
response boarding on the toxic.
The xanthene beverages also create a medical problem.
They are dietary of a stimulant of the CNS. Often the
physicians face the question whether to deny caffeine-
containing beverages to patients or not. In fact children
are more susceptible than adults to excitation by
xanthenes.
For this reason, tea and coffee should be excluded from
their diet.
Determination of Caffeine in Tea Samples doubtful value.
It has a high tannin content may be as high as 50 mg per
cup.
CULTIVATION AND HARVESTING
Tea plantation in southern India
Camellia sinensis is an evergreen plant that grows mainly
in tropical and sub-tropical climates. Nevertheless, some
varieties can also tolerate marine climates and are
cultivated as far north as Pembrokeshire in the British
mainland and Washington in the United States.
Leaves of Camellia sinensis, the tea plant.
Tea plants are propagated from seed or by cutting; it takes
approximately 4 to 12 years for a tea plant to bear seed,
and about 3 years before a new plant is ready for
harvesting. In addition to a zone 8 climate or warmer,
tea plants require at least 127 cm. (50 inches) of rainfall
a year and prefer acidic soils. Traditional Chinese Tea
Cultivation and Studies believes that high-quality tea
plants are cultivated at elevations of up to 1,500 metres
(4,900 ft): at these heights, the plants grow more slowly
and acquire a better flavour.
Only the top 1-2 inches of the mature plant are picked.
These buds and leaves are called flushes. A plant will grow
a new flush every seven to fifteen days during the growing
season, and leaves that are slow in development always
produce better flavored teas.
CONTENT
Tea contains catechins, a type of antioxidant. In a freshly
picked tea leaf, catechins can compose up to 30% of the dry
weight. Catechins are highest in concentration in white
and green teas, while black tea has substantially fewer
due to its oxidative preparation. Research by the U.S.
Department of Agriculture has suggested that levels of
antioxidants in green and black tea do not differ greatly,
with green tea having an Oxygen Radical Absorbance
Capacity (ORAC) of 1253 and black tea an ORAC of 1128
(measured in μmolTE/100g).
Tea also contains theanine and the stimulant caffeine at
about 3% of its dry weight, translating to between 30 mg
and 90 mg per 8 oz (250 ml) cup depending on type,
brand and brewing method. Tea also contains small
amounts of theobromine and theophylline. Due to modern
day environmental pollution fluoride and aluminum
have also been found to occur in tea, with certain types of
brick tea made from old leaves and stems having the
highest levels. This occurs due to the tea plant's high
sensitivity to and absorption of environmental pollutants.
Dry tea has more caffeine by weight than coffee;
nevertheless, more dried coffee is used than dry tea in
preparing the beverage, which means that a cup of brewed
tea contains significantly less caffeine than a cup of coffee
of the same size.
Tea has negligible carbohydrates, fat, and protein.
Although tea contains various types of polyphenols and
tannin, tea does not contain tannic acid. Tannic acid is
not an appropriate standard for any type of tannin
analysis because of its poorly defined composition.
ORIGIN AND HISTORY
Tea weighing station north of Batumi, Russian Empire
before 1915
Tea plants are native to East and South Asia and probably
originated around the point of confluence of the lands of
northeast India, north Burma, southwest China, and
Tibet. Although tales exist in regards to the beginnings of
tea being used as a beverage, no one is sure of its exact
origins. The usage of tea as a beverage is first recorded in
the Chinese classics Shennong Ben Cao Jing. It was
already a common drink during Qin Dynasty (around
200 BC) and became widely popular during Tang Dynasty,
when it was spread to Korea and Japan. Trade of tea by
the Chinese to Western nations in the 19th century spread
tea and the tea plant to numerous locations around the
world.
After all our main stress is on the presence of caffeine in
xanthene beverages and so in this project we will study
and observe the quantity of caffeine varying in different
samples of tea leaves.
DETERMINATION OF CAFFEINE IN TEA SAMPLES
THEORY
The most important methylated alkaloid that occurs
naturally is caffeine. Its molecular formula is CsH10
N4
O2
.
Its IUPAC name is 1, 3, 7-trimethylxanthene and common
name is 1-methylated thiobromine.
Purely it is white, crystalline solid in the form of needles.
Its melting point is 1230
c. It is the main active principle
component of tea leaves. It is present in tea leaves up to 3%
and can be extracted by first boiling the tea leaves with
water which dissolves many glycoside compounds in
addition to caffeine. The clear solution is then treated
with lead acetate to precipitate the glycoside compounds
in the form of lead complex. The clear filtrate is then
extracted with extracts caffeine because it is more soluble
in it then water.
USES OF CAFFEINE
1. In medicine, it is used to stimulate, central nervous
system and to increase flow of urine.
2. Because of its stimulating effects, caffeine has been
used to relieve fatigue. But it is dangerous and one
may collapse if not consumes it under certain limit.
3. Caffeine is also used in analgesic tablets, as it is
believed to be a pain reliever. It is also beneficial in
migraines.
EFFECTS OF CAFFEINE
1. It is psycho – stimulant.
2. It improves physical and mental ability.
3. Its effect in learning is doubtful but intellectual
performance may improve where it has been used to
reduce fatigue or boredom.
4. When administered internally, it stimulates heart
and nervous system and also acts as diuretic. On the
contrary their excessive use is harmful to digestion
and their long use leads to mental retardation.
DETERMINATION OF CAFFEINE IN TEA SAMPLES
PROCEDURE
1. First of all, 50 grams of tea leaves were taken as
sample and 150 ml of water was added to it in a
beaker.
2. Then the beaker was heated up to extreme boiling.
3. The solution was filtered and lead acetate was added
to the filtrater, leading to the formation of a curdy
brown coloured precipitate.
4. We kept on adding lead acetate till no more
precipitate has been formed.
5. Again solution was filtered.
6. Now the filtrate so obtained was heated until it had
become 50 ml.
7. Then the solution left was allowed to cool.
8. After that, 20 ml. of chloroform was added to it. Soon
after, two layers appeared in the separating funnel.
Determination of Caffeine in Tea Samples
1. We separated the lower layer.
2. The solution then exposed to atmosphere in order to
allow chloroform to get evaporated.
3. The residue left behind was caffeine.
4. Then we weighed it and recorded the observations.
Similar procedure was performed with different samples of
tealeaves and quantity of caffeine was observed in them
Determination of Caffeine in Tea Samples
I.Red Label Tea (Brooke Bond)
Weight of china dish 46.60gms
Weight of china dish with precipitate 47.20gms.
Amount of caffeine 0.60gms
2.Yellow Label Tea (Lipton)
Weight of china dish 46.60gms
Weight of china dish with precipitate 47.15gms.
Amount of caffeine 0.55gms
3.Green Label Tea (Lipton)
Weight of china dish 46.60gms.
Weight of china dish with precipitate 47.05gms.
Amount of caffeine 0.45gms.
1. Quantity of caffeine in Red label tea is 60mg. /sample
of 50 gm.
2. Quantity of caffeine in yellow label tea is
55mg./sample of 50 gm.
3. Quantity of caffeine in green label tea is
45mg./sample of 50 gm.
Graphically plotting various tea samples in accordance
with the amount of caffeine present in them we present a
stunning find:
60 mg 55 mg 45 mg
RED LABEL YELLOW LABEL GREEN LABEL
Graphically Represent Amount of Caffeine Present in
Different Samples of Tea
Green Label > Yellow Label > Red Label
0.60
0.55
0.45
Amount of Caffeine in mg
Red Label Tea (Brook Bond)
Yellow Label Tea (Lipton)
Gree Label Tea (Lipton)
References Books:-
Pradeep’s New Course Chemistry – XII
By S.N Khetarpal, S. N. Dhawan, P.N. Kapil
Lab Manual – Comprehensive
Modern abc of Chemistry
By : S.P Jauhar
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