Chemistry

Project
Session : 2023-2024

A Project Report
On
“digestion of starch by salivary
amylase and effect of temperature
and pH on it”

Submitted by - S u n n y
Class – XIIth (Science)

Under the
Guidance of Ms.
Chetna Sehrawat
PGT (Chemistry)

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 Table of
Contents
➢ Certi icate
➢ Declaration
➢ Acknowledgement
➢ Aim of Project
➢ Objective of the Project Report
➢ Introduction
➢ Apparatus Required
➢ Procedure
➢ Observation
➢ Conclusion
➢ Precaution
➢ Bibliography

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 Certi icate
th
This is to certify that Sunny student of class XII (Sci.)
has successfully prepared the report on the Project
entitled “To study the digestion of starch by salivary
amylase and effect of temperature and pH on it” under
the guidance of Ms. Chetna Sehrawat (PGT
Chemistry).The report is the result of his efforts &
endeavours. The report is found worthy of acceptance
as nal Project report for the subject Chemistry of class
XII(sci.).

_______________________ _____________________________
Signature of Teacher Signature of Examiner

____________________________
Signature of Principal

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 Acknowledgement
I would like to express a deep sense of thanks and gra tude to
my project guide Ms. Chetna Sehrawat for guiding me immensely
through the course of the project. He always evinced keen interest
in my project. His construc ve advice & constant mo va on have
been responsible for the successful comple on of his project.

My sincere thank goes to our principal sir for his co-ordina onin
extending every possible support for the comple on
of this project.

Sunny
Class- XIIth (Science)

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 AIM

“ To study the diges on

of Starch by salivary
amylase and
e ect of
temperature and pH
on it. ”

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 Introduction
Every health book insists on the chewing of food. The act of
chewing s mulates the excre on of saliva. Saliva mixes up
with the food and helps its diges on. That is, the enzyme
ptyalin or amylase present in human saliva hydrolyzes the
big molecules of food into many molecules.

For example, starch into mono-saccharides maltose and

glucose; proteins into amino acids and fats into fa y acids
and glycerol.
Thus saliva not only helps in diges on of food but also
convert into energy genera ng substances. Further, enzyme
and their ac vity are very sensi ve to temperature and pH.
Even a slight varia on in these two factors, can disturb the
ac on of enzymes. In other words, diges on of food by
salivary amylase is also e ected by temperature and pH and
can be veri ed experimentally.
For example, hydrolysis of starch can be veri ed by tes ng it
with iodine solu on. Starch forms blue coloured complex
with iodine. If no starch is present in a system it will not give
blue colour with iodine.

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 Apparatus Required
The requirements for experiment of chemistry project reportAre
as follow:
1. Test tubes
2. Test tube stand
3. One dropper
4. Beaker
5. Stop watch
6. Starch
7. Iodine solu on
8. Thermometer
9. Dilute HCl solu on
10. Dilute NaOH solu on

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 Experiment 1
Aim:- To study the diges on of starch by saliva

Procedure for Chemistry Experiment 1 is:

1. Collec on of Saliva:- Rinse mouth thoroughly with cold

water and ensure that it does not contain any food
par cles. Now take about 250ml of lukewarm water in
the mouth and keep for about three minutes so that
salivamixes up well with it. Spit this into a beaker. Filter, if
there is any suspended impurity clear ltrate is saliva
solu on and contains enzyme ptylin.
2. Preparation of starch solution:- Take about 0.5g of starch
in 100ml beaker and add enough water to make a paste.
Dilute the paste by adding 50ml water and boil for about
5 minutes.
3. Digestion of starch:-
a. Take 5ml of the starch solu on in a test tube. Add
2ml of saliva solu on into it. Mix the solu on well
by shaking the tube carefully and start a step watch.
b. A er one minute, take out two drops of the mixture
solu on from the test tube with the help of
dropperand transfer it into another test tube
containing about 1ml of 1% iodine solu on. Note
the colour produced, if any.

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 d. Repeat this test a er every one minute taking two
drops of the mixture solu on and fresh 1% iodine
solu on con nue un l the test shows no blue colour.
e. Record the me and blue colour intensity.

Observation
Time Passed 1 2 3 4
a erMixing minut minut minut minut
e e e e
Colour Intensity Deep Blue Ligh No
Blue t Blue
Blu
e

Absence of blue colour on addition to iodine solution means

absence of starch in the mixture solution. That is whole of the
starch has got digested or hydrolysed.

Conclusion
Starch gets hydrolysed by salivary amylase

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 Experiment 2
Aim:- To study the e ect of temperature on the diges on of
starch by saliva.

Procedure for Chemistry Experiment 2 is:

1. Take three test tubes and label these 1,2, and 3.

2. Take 5ml of the starch solu on, 2ml of the saliva solu on
and 5ml of water in each test tube. And shake the test
tubes carefully.
3. Place test tube number 1 in water at room temperature,
test tube number 2 in a beaker containing water at
50°Cand test tube number 3 in boiling water.
4. A er 5 minutes, observe the colour change on mixing
two drops of the mixture of every tube with one ml of 1%
iodine solu on. Note the intensity of blue coloured form.

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 Observation
Time passed a er Intensity of blue
mixing saliva colour
olu on with
Test tube 1 at
starchsolu on (in room Test tube
Test tube 2 at
min) temperatu 3 iboiling
50°
re wate

5 Light blue Blue Deep

blue

6 No blue Light blue Blue

colour

7 - Faint blue Blue

8 - No blue colour Blue

9 - - Blue

10 - - Blue

Conclusion
Temperature a ects the diges on of starch by
saliva.

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 Experiment 3
Aim:- To study the e ect of pH on the salivary diges on of
starch.
Procedure for Chemistry Experiment 3 is:
1. Take three test tubes and label these 1,2, and 3.
2. Add 5ml of the starch solu on, 2ml of the saliva
solu onin each test tube.
3. Now as 2ml of water in test tube number 1 2ml of
DiluteHCl in test tube number 2 and 2ml of Dilute NaOH
solu on in test tube number 3 and shake carefully.
4. Keep the three test tubes in water at room
temperaturefor about 10 minutes.
5. Add 2 drops of the solu on of each test tube with
1%iodine solu on and observe the colour change.

Observation
Colour produced (in test
Test Solu on taken tube) with 1% iodine
tube solu on
1 Starch + saliva + water No blue colour
2 Starch + saliva +dil. HCl Blue colour
3 Starch + saliva + dil. Blue colour
NaOH

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 Conclusion
Hydrolysis of starch by the enzyme does not take place
inthe acidic or alkaline medium.

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 Bibliography
1. Wikipedia-the free encyclopaedia
2. h p://www.google.com/
3. h p://en.wikipedia.org
4. www.icbse.com
5. Comprehensive Chemistry
th
6.Chemistry NCERT Class XII
7. Dinesh chemistry

Thank you!!

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