BIOLOGY
PROJECT
Acidity in Tea Leaves
Session: 2023-2024
Submitted by :
LAKSHAY
SHARMA Guided By: Ms.
ANU
Class: XII- A
Acknowledgment
I take this opportunity to express my gratitude towards my
chemistry teacher MS.Anu, for her precious and valuable
guidance which played a crucial role in not only my
investigatory project on the topic “Acidity of tea leaves”, but
also throughout the session with my studies. I am very grateful
to the school as well, for giving me this opportunity.
Last but not the least I would like to thank my parents and
friends for helping me in this project.
Index
1. Abstract
2. Theory
3. Requirements
4. Procedure
5. Observation
6. Result
7. Bibliography
Abstract
Aim: To compare the acid content of acid in different
samples of leaves.
Tea can be described as an agricultural plant that is industrially
important because of the produce of its leaves, when immersed
in hot water. Tea however is an aromatic beverage that can be
prepared in several different ways.
Each method of preparation has a certain effect on the acidity of
the beverage. My aim in this experiment is to capture the
difference in the acidity of the beverage by analyzing the
mixture in different ways.
Tea after water, is the world’s most popular beverage of
consumption, as it is not extremely expensive, and has a pleasant
texture and aroma. The leaves of the tea plant are oxidized and
cured. The leaves are then introduced into hot/boiling water,
which causes a release in the flavor and color contained in the
leaf of the plant. Some people prefer to drink tea in this form,
while others prefer it with milk. Some people add sugar. All
these activities cause different outcomes in the pH value of the
beverage.
Theory
Tea contains catechins, a type of antioxidant. In a freshly picked
tea leaf, catechins can comprisal up to 30% of the dry weight.
Tea also contains L-threonine, and the stimulant caffine at about
3% of its dry weight depending on the type, brand and brewing
method.
Tea also contains small
amounts of the bromine
and theophylline. Due to
modern environmental
pollution, fluoride and
aluminum have also been
found to occur in tea.
Tannic Acid in tea is
actually a myth, a rather
popular one. The acidity
of tea leaves is not due to
the tannic acid. Tea
contains polyphenols or
catechins which are a
specific type of tannin.
The oxalic acid present in the tea leaves is precipitated as
calcium oxalate by treatment of aqueous solution of tea with
calcium carbonate. Calcium oxalate is then hydrolysed with
conc. H2SO4 and recrystallized from water.
Requirements
1. 10gm of three different types of tea leaves
2. Calcium Carbonate (CaCO3)
3. Filter Paper
4. Funnel
5. Beaker
6. Tripod Stand
7. Bunsen Burner
Procedure
1. Weigh exactly 10gm of 1st sample of tea leaves.
2. Take 200ml of distilled water in a beaker.
3. Put tea leaves in above beaker boil it for 10 minutes.
4. Filter above boiled solution using funnel and filter paper in
another beaker.
5. In filtrate add 4gms of CaCO3 and boil it.
6. Filter above boiled
solution using funnel
and filter paper in
another beaker. There
will be a ppt. of
Calcium oxalate on the
filter paper.
7. Keep filter paper
aside and let it dry.
8. Weigh the ppt. of oxalic acid.
9. Repeat the above steps for the other two samples.
Observation
Sr. Weight of Weight of Percentage of
Brand of tea
no. tea leaves acid obtained oxalic acid
1 Red Label 10gm 0.91gm 9.1%
2 Twining’ 10gm 0.97gm 9.7%
3 Taj Mahal 10gm 0.80gm 8.0%
Result
Twining’s has high amount of oxalic acid among Red Label, Taj
Mahal, and Twining’s.
Thus, Twining’s has a good flavor.
Bibliography
www.wikipedia.com
https://www.healthline.com/health/food-nutrition
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