This week we had the lab practice to proof the presence and action of salivary amylase and the effect of pH.
The previous concepts needed were: Starch / Amylase / Iodine test
- Starch (or amylum) is a carbohydrate consisting of a large number of glucose units joined together.
- Amylase is an enzyme that breaks starch down into sugar. Amylase is present in human saliva, where it begins the chemical process of digestion. Amylase splits starch to maltose.
- The Iodine test is used to test for the presence of starch.
Iodine solution (or lugol) reacts with starch producing a blue black color.
In the picture you can see two test tubes with the different iodine test results: positive (black) and negative (some orange)
The amylase action in a clear video:
And here the worksheet for this practice
One advice, it is better to chew for a couple of minutes the piece of bread inside your mouth in order to get a clear negative iodine test result.
Spitting is always funny.
This group performed a very good work in the laboratory.+
Next image is useful to sum up the practice and show the results (the picture was taken the day after the practice so the iodine test results are more clear in colour).
The important objective of this practice was to understand and be able to explain the Iodine test results in the four different test tubes.
These were some useful websites to prepare this practice: