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KENDRIYA VIDYALAYA
AFS
KENDRIYA V HAKIMPET
BIOLOGY INVESTIGATORY PROJECT
2019-20
TO DETERMINE CONTENT OF CAFFEINE
IN DIFFERENT TEA SAMPLES
NAME OF THE STUDENT : AYUSHI MISHRA
CLASS & SECTION : XII – ‘A’
ROLL NO. :
CERTIFICATE
It is hereby to certify that, the original and genuine
investigation work has been carried out to
investigate about the subject matter and the related
data collection and investigation has been completed
solely, sincerely and satisfactorily done by
AYUSHI MISHRA of Class XII, Kendriya
Vidyalaya AFS Hakimpet, regarding the project
titled, “ TO DETERMINE THE CONTENT OF
CAFFEINE IN DIFFERENT SAMPLES OF
TEA.”
___________________ ________________
SIGNATURE OF INTERNAL signature of external
EXAMINER EXAMINER
_________________
SIGNATURE OF PRINCIPAL
ACKNOWLEDGEMENT
The successful completion of any task would be
incomplete without mentioning the names of those persons
who helped to make it possible. I take this opportunity to
express my gratitude in few words and respect to all those
who helped me in the completion of this project.
It is my humble pleasure to acknowledge my deep senses of
gratitude to my Biology teacher, Mrs. E. Vandana Reddy
for her valuable support, constant help and guidance at each
and every stage, without which this project would not have
come forth.
I also register my sense of gratitude to our principal,
Mr. K. N . Prasad for his immense encouragement that
has made this project successful. I would also like to thank
my friends and family for encouraging me during the course
of this project.
Last, but not the least, I would like to thank CBSE for
giving us the opportunity to undertake this project.
CONTENTS
Aim
Apparatus & Chemicals Required
Introduction
Theory
Procedure
Observation
Inference
Bibliography & References
AIM
TO DETERMINE THE
CONTENT OF
CAFFEINE IN
DIFFERENT SAMPLES
OF TEA….
APPARATUS REQUIRED
1 . Round Bottom Flask
2. Bunsen Burner & Match Stick
3. Beakers(250ml & 75 ml)
CHEMICALS REQUIRED
1.Basic Lead Nitrate
2. Lead Oxide
3. Chloroform
4. Distilled water
5. Animal Charcoal
6. Dilute Mineral Acid
INTRODUCTION
Tea is a highly popular drink all over the world. A cup of tea
is often taken as a mind-freshener. This can be primarily
attributed to the presence of a stimulant called
CAFFEINE in the tea. Besides this tea also contains
various polyphenolic compounds that act as flavourings
agents. Relative contents of these compounds result in
different varieties available under different brand names.
The quality of tea leaves also greatly influences the taste of
the tea .Tea is popular name of the tropical plant whose
botanical name is Camellia thea. India is the largest
producer of good quality tea and it is mainly grown in slope
of hills of Assam, West Bengal and Nilgiri Hills. A cup of
Indian tea contains 80mg of caffeine which is the
indispensable content of tea.
Caffeine is a nitrogenous organic compound of alkaloid
group. These groups of substances have a marked
physiological effect on the human body when taken in
considerable amount. It is widely used as a stimulant of the
central nervous system and also has hypotonic and sleep
inducing effect.
It occurs as a white powder that melts at around 2380C. It
is fairly soluble in hot water and on cooling the solution
gives crystals made up of caffeine monohydrate. In this case
the compound is less soluble in organic solvents than in hot
water. It is odourless but even a small amount has a very
bitter taste. Caffeine is the main flavouring agent in the tea
leaves. It is obtained from the decaffeination of tea dust and
also from coffee.
It exerts a simulative effect on the cerebral cortex but later
has a depressant and narcotic action. It is also useful in
cardiac dropsy. An abnormal sate arising from caffeine is
called caffeinism. The main symptoms are nervousness,
Insomnia and Tachycardia. It is used in medicines in
the form of chlorides and nitrates.
In this project we will do a careful study of different
brands of tea and will extract and carefully analyse
their caffeine content. The result would thus tell the
exact content of caffeine present in different samples
analysed.
Theory
The most important methylated alkaloid that occurs naturally
is caffeine. Its molecular formula is C8H10N4O2. Its IUPAC name
is 1, 3, 7-trimethylxanthene and common name is 1-methylated
theobromine.
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 .
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.
Procedure
In a litre round bottom flask take 40gm of first sample .
To this add about 250ml of distilled water and the contents
are refluxed for about an hour.
Separate the brown colour extracted by decantation followed
by filtration when still hot.
Dissolve Lead acetate into water in 250ml beaker.
The solution is boiled, and the lead oxide is added slowly to the
boiling solution with constant stirring.
It is filtered and again boiled.
The filtrate thus obtained is added dropwise to this extract till
no precipitation occurs.
The filtrate is treated with animal charcoal to decolourise
extract.
The clear solution is extracted with 100mg of chloroform after
separating by filtration.
The total solution is taken into distillation flask to remove the
solvent by distillation.
The residue left in the flask is dissolved in minimum amount of
hot water and the dissolved contents are transferred to the
boiling tube.
The solution is kept for slow crystallization.
When the white crystalline solid comes out of the solution it is
filtered, dried in desiccators and weighed.
The above procedure is repeated for all samples of tea.
The observations are carefully recorded.
OBSERVATION
About 40gm of each sample was taken. The contents of caffeine
of the samples were noted and their presence in terms of
percentage was calculated.
NAME OF CAFFEINE PERCENTAGE TASTE
THE TEA CONTENTS COMPOSITION
VARIETY
0.029 0.0725% MILD AND
RED SOOTHING
LABEL
0.05 0.0125% SLIGHTLY
TAJ STRONG
MAHAL
STRONG
TATA 0.036 0.09% PLEASANT
TEA
VERY STRONG
LIPTON 0.047 0.1175%
INFERENCE
From the caffeine content and the
taste of the tea as described above
shows that , greater the amount of
caffeine, the greater is the bitterness
and stimulating effect of the tea.
BIBLIOGRAPHY
Parts of this project have been referred from foreign
sources and have been included in this investigatory project
after editing.
References
The references of the sources are as follows:
Books:
Together With Lab Manual Biology - XII
Comprehensive Biology - 12
Internet sources:
www.wikipedia.org
www.google.com
www.yahoo.com
