Experiment 1: enzyme in Food

Amylase is offered by humans to facilitate digestion. Specifically, it is an enzyme the breaks down starch molecules right into glucose molecules. This is why world sometimes watch a sweet taste after ~ sucking on a strength containing food because that an extended duration of time. Amylase is found naturally in human being saliva and also the pancreas. However, it is additionally present in few of the common plant foods consumed by humans.

You are watching: Experiment 1: enzymes in food

This experiment tests for the existence of amylase in food by using Iodine-Potassium Iodide, IKI. IKI is a shade indicator used to detect starch. This indicator transforms dark purple or black color in color when in the visibility of starch. Therefore, if the IKI systems turns to a dark purple or black color during the experiment, one deserve to determine the amylase is not present (because existence of amylase would break down the strength molecules, and the IKI would certainly not readjust color).



(1) 2 oz. Bottle (Empty)(1) 100 mL graduated Cylinder30 mL Iodine-Potassium Iodide, IKIPermanent MarkerRuler2 Spray Lids30 mL starch (liquid)*Cutting Board


*2 Food assets (e.g., sweet potato, apple, potato, corn, etc.)

*Ginger Root*Kitchen Knife*Paper Towels (non-starch containing)*Saliva Sample *Tap Water

*You have to Provide


1. Eliminate the lid from the strength solution. Affix the spray lid to the strength solution.

2. Rinse the end the empty two ounce bottle v tap water. Usage the 100 mL graduated cylinder come measure and also pour 30 mL the IKI into the empty 2 ounce bottle. Affix the staying spray lid to the bottle.

3. Use a long-term marker to produce four quadrants that equal size by drawing two perpendicular currently that intersect in the facility of the record towel (Figure 3).


Figure 3: Paper bath towel set-up.

4. Spray the sectioned paper towel and another blank record towel v the starch solution. Permit the starch to dry for about one hour (this time interval might vary through location).

5. Once the paper towels are totally dry, brand the blank paper towel “saliva” and collection it aside come be supplied in step 14.

6. Usage the permanent marker to brand the peak left quadrant of the sectioned paper towel “positive control” and also the top right quadrant “negative control”.

7. Select two food items from her kitchen cabinet or refrigerator, and obtain a new ginger root sample.

Note: If ginger root is no available, use banana as a positive control. Be sure to change data tables and also labels accordingly.

8. Acquire a kitchen knife and also a cut board. Carefully cut your 2 selected food items and the ginger source to reveal the inner surfaces. Clean or rinse the knife in between cuts.

9. Collection up a positive control for this experiment. Use the irreversible marker to add the label “ginger root” under the positive manage label. Carefully rub an area in the positive manage quadrant with the fresh surface of the ginger source (which is recognized to contain amylase). Certain a an excellent application by firmly pressing the exposed surface of the root onto the paper towel. Permit the area rest.

10. Set-up a an adverse control because that this experiment in the “negative control” quadrant. Use your knowledge of the scientific method and experimental controls to develop this component. Recognize your an adverse control in Table 1.

Hint: What result would you expect if amylase to be not current when tested with IKI solution?

11. Usage the long-term marker to brand the bottom 2 quadrants v the surname of the 2 food item you decided to test for amylase.

12. Carefully, however firmly, rub the fresh/exposed area of the food items on the paper towel in their designated quadrants back and soon 10 - 15 times.

13. Enable the locations to dry because that at least five minutes.

14. While you wait, administer a saliva sample through spitting right into the center of the file towel labeling “saliva” that you all set with starch in step 5. Spread the saliva out by gently rubbing the halves the the file towel together.

15. After your food samples and controls have rested for at least five minutes, test them with IKI solution.

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Note: usage caution once spraying the IKI solution. Organize the IKI spray party 25 - 30 cm away indigenous the document towel, and also mist the IKI equipment over every quadrant.

16. Allow the IKI systems to dry. Watch where and also what color develops, and consider what these results indicate. Document your outcomes in Table 1.

Table 1: substance vs. Strength Presence


Resulting Color

Presence the Starch?

Positive Control: Ginger Root



Negative Control: Student need to Select



Food Product:



Food Product:






Post-Lab Questions

1. What were your controls because that this experiment? What go they demonstrate? Why to be saliva consisted of in this experiment?

2. What is the role of amylase? What go amylase execute to starch?

3. I m sorry of the foods items that girlfriend tested contained amylase? Which go not? What experimental evidence supports her claim?

4. Saliva does no contain amylase until babies are two months old. How can this impact an infant’s digestive requirements?

5. Over there is an additional digestive enzyme (other than salivary amylase) the is secreted by the salivary glands. Study to identify what this enzyme is called. What substrate does it act on? wherein in the body does it end up being activated, and also why?

6. Digestive enzymes in the gut incorporate proteases, i beg your pardon digest proteins. Why don’t these enzymes digest the stomach and little intestine, which are partly composed that protein?