G H RAISONI PUBLIC SCHOOL,
SUKALI
CHEMISTRY
INVESTIGATORY PROJECT ON
Study of digestion of starch by
salivary amylase and effect of pH
and temperature on it.
Submitted by: Prathamesh Katole
Class: XII ( C )
Session – 2024-25
Guided by: Ms Neha Kumbhare
ACKNOWLEDGEMENT
First of all, I am immensely indebted to almighty god for his blessings and grace
without which I would not have undertaken the task and my efforts would never
have been a success. I humbly consider it as a privy love and honour to
Mrs. Meenakshi Bhatia, Principal of GHRPS Sukali for her appropriate
direction, valuable suggestion, under judging assistance so generously extended
to me.
I wish to express my deepest feeling of gratitude to Ms Neha ma’am
Chemistry Project Guide, GHRPS Sukali for her erudite involvement and
sustained guidance which has been pivotal in my project work. Their minute
observation, precious incites, critical comments have indeed greatly helped to
shape my ideas. The guidance and support received from my entire classmate
was vital for the success of this project. I also own a sense of gratitude to my
parents for encouragement and support throughout the project.
By,
Prathamesh Katole
G H RAISONI PUBLIC SCHOOL,
SUKALI CERTIFICATE
This is to certify that, a student of class XII ( C ) has successfully completed
the research on the topic of Study of digestion of starch by salivary amylase and
effect of pH and temperature on it, under the guidance of Ms. Neha
Kumbhare for the partial fulfilment of AISSCE as prescribed by the CBSE in
the year
2024-2025.
Internal Examiner Signature:
External Examiner Signature:
Principal Signature:
INDEX
Introduction
Aim
Theory
Procedure
Observations
Results
Precautions
Bibliography
INTRODUCTION
Every health book insists on the chewing of food. The act of chewing
stimulates the excretion of saliva. Saliva mixes up with the food and
helps its digestion. 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-saccnaricies maltose and glucose;
proteins into amino acids and fats into fatty acids and glycerol. Thus,
saliva not only helps in digestion of food but also convert into
energy generating substances. Further, enzyme and their activity are
very sensitive to temperature and pH. Even a slight variation in these
two factors, can disturb the action of enzymes. In other words,
digestion of food by salivary amylase is also affected by temperature
and pH and can be verified experimentally. For example, hydrolysis of
starch can be verified by testing it with iodine solution. Starch forms
blue coloured complex with iodine. If no starch is present in a system it
will not give blue colour with iodine.
EXPERIMENT: 1
AIM: To study the digestion of starch by saliva
APPARATUS:
Beaker,
Starch,
Test Tube,
Dropper,
Iodine Solution,
Stopwatch
PROCEDURE:
1. Collection of Saliva: -
Rinse mouth thoroughly with cold water and ensure that it does not contain
any food particles. Now take about 250ml of lukewarm water in the mouth
and keep for about three minutes so that saliva mixes up well with it. Spit this
into a beaker. Filter, if there is any suspended impurity clear filtrate is saliva
solution 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 solution in a test tube. Add2ml of saliva solution
into it. Mix the solution well by shaking the tube carefully and start a
step watch.
b. After one minute, take out two drops of the mixture solution from the
test tube with the help of dropper and transfer it into another test tube
containing about 1ml of 1% iodine solution. Note the colour produced, if
any.
c. Repeat this test after every one minute taking two drops of the mixture
solution and fresh 1% iodine solution continue until the test shows no
blue colour.
d. Record the time and blue colour intensity
Time Passed after 1 Minute 2 Minute 3 Minute 4 Minute
Mixing
Colour Intensity Deep Blue Light No Blue
Blue Blue
OBSERVATION:
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 hydrolyzed.
CONCLUSION:
Starch gets Hydrolyzed by salivary Amylase
EXPERIMENT: 2
AIM: To study the effect of temperature on the digestion of starch by saliva
APPARATUS:
Test Tube,
Dropper,
Iodine Solution,
Thermometer.
PROCEDURE:
1. Take three test tubes and label these 1, 2 and 3.
2. Take 5ml of the starch solution, 2ml of the saliva solution 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°C and test tube number 3 in boiling
water.
4. After 5 minutes, observe the colour change on mixing two drops of the
mixture of every tube with one ml of 1% iodine solution. Note the
intensity of blue coloured form.
OBSERVATION:
Time Passed after Intensity of blue colour
mixing saliva
Test Tube 1 at Test Tube 2 at Test Tube 3 in
solution with
room temp. 50°C Boiling water
starch solution (in
mins)
5 Light Blue Blue Deep Blue
6 No Blue colour Light Blue Blue
7 - Faint Blue Blue
8 - No Blue Colour Blue
9 - - Blue
10 - - Blue
CONCLUTION:
Temperature affects the digestions of starch by Saliva.
EXPERIMENT 3:
AIM: To study the effect of Ph on the salivary digestion of starch.
APPARATUS:
Test Tube,
Dropper,
Starch Solution,
Dilute HCL,
Dilute NaOH,
Iodine Solution,
Thermometer.
PROCEDURE:
1. Take three test tubes and label these 1, 2 and 3.
2. Add 5 ml of starch solution, 2 ml of saliva solution in each test tube.
3. Now add 2 ml of water in test tube number 1, 2 ml of Dilute HCL in test
tube number 2 and 2 ml of Dilute NaOH in test tube number 3 and shake
carefully.
4. Keep the three test tubes in water at room temperature for about 10
mins.
5. Add 2 drops of the solution of each test tube with 1% iodine solution
and observe the colour change.
Test Tube Solution Taken Colour produced (in test tube)
with 1% iodine solution
1 Starch + Saliva + Water No Blue Colour
2 Starch + Saliva Blue Colour
3 Starch + Saliva + dil. NaOH Blue Colour
OBSERVATION:
CONCLUION:
Hydrolysis of starch by the enzyme does not take place in the acidic or
alkaline medium
PRECAUTION:
1. All apparatus should be clean and washed properly.
2. Add equal drops of iodine in all the samples while testing for starch.
3. Temperature variation affects enzyme activity, so take the readings at a
constant temperature for all the samples.
4. Delay in sampling or the reaction time may affect the result. So, iodine
drops must be added at fixed intervals in all samples.
BIBLIOGRAPHY:
• www.google.com .
• www.icbse.com
• www.Wikipedia.org
• NCERT Chemistry XII
• Comprehensive Practical Manual
THANK YOU!!
-Prathamesh Katole
