The main purpose of this experiment was to see when/how Amylase enzyme in our salivary has an effect on the starch we digest. We will use Iodine to indicate the presence of starch. If the starch doesn't get hydrolyzed, we will get a blue color when we add the Iodine ions. If the starch gets hydrolyzed, no changes will be seen. We will also try to demonstrate the pH conditions needed by the enzyme to work, by using HCl.
Test tube rack
One clean Rubber band
1%starch solution (prepared before; 1 G soluble starch to 100 ml boiling water)
Iodine test solution
2 M HCI (hydrochloric acid)
1. We collected saliva from a person in our group.
2. We labeled the tubes with names: A, B, C and D
3. The salvia was equally spread on 2 of the tubes, A and B
4. 2 Drops of HCl acid in tube B and D
5. 10 drops of 1% starch in every tube.
6. Placed the tubes in water that was approximately 37 C, and they where there for about 15 mins.
7. Added Iodine to each tube and recorded the results.
Tube A: No changes at all, the color is still the same. pH Value is 8
Tube B: We got some blue, but a very little.
Tube C: Completely dark blue.
Tube D: Completely dark blue.
The starch got hydrolyzed to maltose, and maltose cant react with Iodine. Therefore we didn`t get the blue color. In the second tube, B, there was a slight color change. According to the groups conclusion the enzyme should not have managed to dissolve the starch, but it did. The HCl should have created an environment that has a lover pH value and the enzyme wouldn't do its job. The C and D tubes are control tubes, these where treated like the other tubes, just without the amylase enzyme. Both tubes got a blue color that proves the fact that the enzyme is really doing the job, nothing else.
Here we see that the Amylase enzyme turns the starch into maltose and helps our body to digest it. On the other hand, the enzymes only work within a certain pH value. If it`s any lower it doesn't work.