Chemistry Project Report on
To Study the Digestion of Starch by Salivary Amylase and
Effect of pH and Temperature on it
Submitted by :
Class XII (CBSE)
Sr. Sec. School
- Objectives of the Project
- Material Required
This is to certify that the investigatory Chemistry project
“To Study the digestion of starch by salivary amylase
and effect of temperature and pH on it”
has been completed under my supervision.
As a student of class XII, I did this project as a part of my studies
entitled “To Study the digestion of starch by salivary amylase and effect of
temperature and pH on it”
I owe a deep sense of gratitude to my chemistry teacher whose valuable
advice, guidance help me in doing this project from conception to completion.
At the same time I can't forget to express my thankfulness to Principal of
our School for extending his generous patronage and constant encouragement.
Finally, I am thankful to my parents for helping me economically and my
friends for giving me a helping hand at every step of the project.
(Signature of Student)
Objectives 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”
- To study digestion of starch by saliva.
- To study the effect of temperature on the digestion of starch by
- To study the effect of pH on the salivary digestion of starch.
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
hydrolyse the big molecules of food into many molecules. For example starch into
mono-saccharides maltose and glucose; proteins into amino acids and fats into
fatty acids and glycerol. Thus saliva not only helps in digestion of food but
convert it into energy generating substances. Further, enzymes and their
activity are very sensitive to temperature and pH. Even a slight variation in
these two factors, can disrupt the action of enzymes. In other words, digestion
of food by salivary amylase is also effected by pH and temperature 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.
Requirements for Chemistry Project Report
The requirements for experiment of Chemistry Project Report are as under :
- Test tubes
- Test tube stand
- One dropper
- Stop watch
- Starch and Iodine solution
- Dil. HCl and Dil NaOH solution.
Chemistry Experiment Procedure
Procedure for Chemistry Experiment is :
1) Collection of Saliva - Rinse mouth throughly with cold water and ensure
that it does not contain any food particles. Now take about 20ml of lupe warm
water in the mouth and gangle 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 ptyalin.
2) Preparation of starch solution - Take about 0.5g of starch in a 100ml
beaker and add enough water to make a paste. Dilute the paste by adding 50ml
water and boil for about 5 min.
3) Digestion of starch (a) take 5ml of the starch solution in a test tube.
Add 2 ml of saliva solution into it. Mix the solutions 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 a dropper and transfer it
into another test tube containing about one ml 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. Record the time and blue colour intensity.
|Time Passed after mixing
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
Procedure : Effect of temperature on the digestion of starch by saliva.
- Take three test tubes and label these 1, 2, 3.
- Take 5ml of the starch solution, 2ml of the saliva solution and 5 ml of
water in each test tube.
- Place test tube No. 1 in water at room temperature, test tube No.2 in a
beaker containing water at 500 C and test tube No.3 in boiling
- 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.
Starch get hydrolysed by saliva amylase.
Procedure : To study the effect of pH on the salivary digestion of
- Take three test tubes and label these 1, 2, 3.
- Add 5ml of the starch solution, 2ml of the saliva solution in each test
- Now add 2 ml of water inn test tube No. 1, 2 ml of dil HCl in test tube
No. 2 and 2ml of dil NaOH solution in test tube No. 3 and shake carefully.
- Keep the three test tubes in water at room temperature for about 10
- Add two drops of the solution of each test tube with 1% iodine solution
and observe the colour change.
Temperature effects the digestion of starch by saliva with increase in temp
salivary analyse get inactivated and process of digestion do not take place.
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