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Chemistry

Project

Session : 2020-2021

A Project Report On

“digestion of starch by salivary amylase

and effect of temperature

and pH on it”

Submitted by Samuel Kumar Class – XIIth (Science) Roll no. (cbse) – ______

Under the Guidance of

Mr. S.P. Gupta Sir PGT (Chemistry)

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Table of Contents

 Certificate  Declaration  Acknowledgement  Aim of Project  Objective of the Project Report  Introduction  Apparatus Required  Procedure  Observation  Conclusion  Precaution  Bibliography

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Kendriya Vidyalaya Khagaria

Certificate

This is to certify that SAMUEL KUMAR student

of class XIIth (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

Mr. S.P.GUPTA (PGT Chemistry).

The report is the result of his efforts & endeavours.

The report is found worthy of acceptance as final

Project report for the subject Chemistry

of class XIIth (sci.).

Signature of Chemistry Teacher Signature of External Examiner

--------------------------- --------------------------

Signature of Principal

-----------------------------

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Declaration

I hereby declare that the project work entitled

“ To study the digestion of starch by

salivary amylase and effect of temperature

and pH on it ” , submitted to Department of chemistry,

Kendriya Vidyalaya Khagaria is prepared by me.

SAMUEL KUMAR Class: XIIth (Science)

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Acknowledgement

I would like to express a deep sense of thanks and gratitude

to my project guide Mr. S.P. Gupta sir for guiding me immensely

through the course of the project. He always envinced keen

intrest in my project. His constructive advice & constant

motivation have been responsible for the successful completion

of his project.

My sincere thank goes to our principal sir for his co-ordination

in extending every possible support for the completion

of this project.

I must thanks to my classmates for their timely help and

support for completion of this project.

Last but not the least, I would like to thank all those who had

helped directly or indirectly towards the

completion of this project.

SAMUEL KUMAR

Class- XIIth (Science)

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AIM

“ To study the digestion of

Starch by salivary amylase

and

effect of temperature

and pH on it. ”

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Objective of the Project Report

The main objective of this chemistry project report is

“To study the digestion of starch by salivary amylase

and effect of temperature and pH on it” .

1. To study the digestion of starch by saliva.

2. To study the effect of temperature on the digestion of

starch by saliva.

3. To study the effect of pH on the salivary digestion of

starch.

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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 effected 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.

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Apparatus Required

The requirements for experiment of chemistry project report

Are as follow:

1. Test tubes

2. Test tube stand

3. One dropper

4. Beaker

5. Stop watch

6. Starch

7. Iodine solution

8. Thermometer

9. Dilute HCl solution

10. Dilute NaOH solution

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Experiment 1

Aim:- To study the digestion of starch by saliva

Procedure for Chemistry Experiment 1 is:

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. Add

2ml 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.

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c.

d. 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.

e. Record the time and blue colour intensity.

Observation

Time Passed after

Mixing

1

minute

2

minute

3

minute

4

minute

Colour Intensity Deep

Blue

Blue Light

Blue

No Blue

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 effect of temperature on the digestion 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 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.

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Observation

Time passed after

mixing saliva

solution with starch

solution (in min)

Intensity of blue colour

Test tube 1 at

room

temperature

Test tube 2 at 50°𝑪 Test tube 3 in

boiling water

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

Conclusion

Temperature affects the digestion of starch by

saliva.

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Experiment 3

Aim:- To study the effect of pH on the salivary digestion of

starch.

Procedure for Chemistry Experiment 1 is:

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

2. Add 5ml of the starch solution, 2ml of the saliva solution

in each test tube.

3. Now as 2ml of water in test tube number 1 2ml of Dilute

HCl in test tube number 2 and 2ml of Dilute NaOH

solution in test tube number 3 and shake carefully.

4. Keep the three test tubes in water at room temperature

for about 10 minutes.

5. Add 2 drops of the solution of each test tube with 1%

iodine solution and observe the colour change.

Observation

Test tube Solution taken

Colour produced (in test

tube) with 1% iodine

solution

1 Starch + saliva + water No blue colour

2 Starch + saliva +dil. HCl Blue colour

3 Starch + saliva + dil. NaOH Blue colour

Conclusion

Hydrolysis of starch by the enzyme does not take place in

the acidic or alkaline medium.

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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.

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Bibliography

1. Wikipedia-the free encyclopedia

2. http://www.google.com/

3. http://en.wikipedia.org

4. www.icbse.com

5. Comprehensive Chemistry

6. Chemistry NCERT Class XIIth

7. Dinesh chemistry

Thank you!!

-Samuel kumar