ACKNOWLEDGEMENT

This is to certify that KUNAL CHUGH has made a project on study of digestion of starch by salivary amylase and effect of pH and tempersture on it under the guidance of Mrs. Rakhi Gakhar.

I thank Mrs. Rakhi Gakhar for the help and guidance provided to me in completing the project.

I would also like to thank the principal for permitting the use of the resources of the school for performing the experiments.

Name of the Student: KUNAL CHUGHRoll Number: 5634780

. Teacher’s Signature

INDEX1) Introduction2) Objective 1: To study the digestion of starch by saliva3) Objective 2: To study the effect of temperature on the

digestion of starch by saliva.4) Objective 3: To study the effect of pH in salivary

digestion of starch.5) Bibliography

INTRODUCTIONEvery health book insists on chewing of food. The act of chewing stimulates the excretion of saliva. Saliva mixes up with food and helps it digestion. i.e. the enzyme ptyalin or amylase present in human saliva hydrolyses the big molecules of food into many smaller molecules for e.g. starch into monosaccharide maltose and glucose, proteins into amino acids and fats into fatty acids and glycerol. Thus saliva not only helps in digestion of food but converts 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 affected by pH and temperature and can be verified experimentally. For e.g., hydrolysis of starch can be verified by testing it with iodine solution. Starch forms blue colored complex with iodine, if no starch is present is present in the system it will not give blue color with iodine.

OBJECTIVE 1: To study the digestion of starch by saliva.

APPARATUS:1. Test Tubes2. Test tube stand3. One dropper4. Beakers5. Stop watch

CHEMICALS:1. Starch2. Iodine solution.

PROCEDURE:1) Collection of saliva

Rinse your mouth thoroughly with cold water and ensure it does not contain any food particles. Now take about 20ml of luke warm water in the mouth and gargle 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 minutes.

3) Digestion of starch. (a) Take 5 ml of the starch solution in a test tube. Add 2 ml of the saliva solution into it. Mix the solutions well by shaking the tube carefully and start a stop watch. (b) After one minute take out two drops of the mixture solution from one test tube with the help of a dropper and transfer it into another test containing about one ml of 1% iodine solution. Note the color produced, if any. (c) Repeat this test every one minute taking two drops of the mixture solution and fresh 1% iodine solution. Continue until the test shows no blue color. Record the time and blue color intensity.OBSERVATION: Room Temperature =37 Degree Celsius

Time passed after mixing

1 min 2 min 3 min ……….. ‘t’ min

Color intensity Deep blue

Blue Light Blue

……….. No blue color.

Absence of blue color 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 saliva amylase.

OBJECTIVE 2: To study the effect of temperature on the digestion of starch by saliva.APPARATUS:

1) Test tubes2) Test tube stand3) One dropper4) Beakers5) Thermometer

CHEMICALS: 1) Starch2) 1% iodine solution.

PROCEDURE:1) Prepare the starch and saliva solutions as described in objective 1.2) Take three test tubes and label these as 1,2 and 3.3) Add 5 ml of the starch solution, 2 ml of the saliva solution and 5 ml,

water in each test tube.4) Mix the solution of each tube, well by shaking it carefully.5) Place test tube no. 1 in water at room temperature, test tube no. 2 in a

beaker containing water at 50 degree Celsius and test tube no. 3 in boiling water.

6) After 5 minutes, observe the color change on mixing two drops of the mixture of every tube with one ml of 1% iodine solution (similar to objective 1). Note the intensity of blue colored form.

OBSERVATION: Room Temperature=37 degree Celsius.

Time passed after mixing

Intensity of blue color in test tube no. 1

Intensity of blue color in test tube no. 2

Intensity of blue color in test tube no. 3

5 minutes Light blue Blue Deep Blue6 minutes No blue color Light Blue Blue7 minutes No blue color Very light blue Blue8 minutes No blue color No blue color Blue9 minutes No blue color No blue color Blue10 minutes No blue color No blue color Blue

Absence of blue color means absence of starch in the mixture. In other words, digestion of whole of the starch.CONCLUSION: Temperature affects the digestion of starch by saliva.

OBJECTIVE 3: To study the effect of pH on the salivary digestion of starch.APPARATUS:

1) Test tubes2) Test tube stand3) One dropper4) Beakers

CHEMICALS:1) Starch 2) 1% iodine solution3) Diluted HCl4) Diluted NaOH solution.

PROCEDURE: 1) Prepare the starch and saliva solutions as described in objective 1.2) Take three clean test tubes and label these 1,2, and 3.3) Add 5 ml of the starch solution and 2ml of the saliva solution in each

test tube.4) Now add 2ml of water in test tube no. 1-2 ml of dilute HCl. In test

tube no. 2 and 2 ml of dilute NaOH solution in test tube no. 3 and shake carefully.

5) Keep the three test tubes in water at room temperature for about 10 minutes.

6) Test two drops of the solution of each test tube with 1% iodine solution and observe the color change.

OBSERVATION:ROOM TEMPERATURE= 37 degree Celsius.

Test Tube no. Color produced with 1% iodine solution

1. (starch + saliva) No blue color2. (starch + saliva + dilute HCl) Blue color3. (starch + saliva + dilute NaOH) Blue color

CONCLUSION: pH effects the digestion of starch by saliva. That is amylase hydrolysis of starch does not take place in the acidic or alkaline medium.

BIBLIOGRAPHY

Oxford Encyclopedia Internet Websites

- www.google.com - www.wikipedia.com - www.amazon.com

Chemistry lab manual NCERT biology