Effect of Detergent on Gelatin


“How Good Is Your Enzymatic Detergent?


In nature there are enzymes called proteases that “digest” or degrade proteins. Some of these enzymes have been genetically engineered and added to our laundry detergents in the hope that they will “digest” the protein off of our clothing. Do they work? Do they assist in cleaning? In this experiment you can compare different detergents and their ability to “digest” protein.
What is gelatin? Gelatin consists of protein chains that are easily digested into their amino acid components. Gelatin is prepared from collagen, a protein found in animal tendons and skin and taken out during the meat rendering process. Boiling collagen reduces the  weight by about one-third and separates the protein strands by breaking bonds. When the boiled collagen is cooled, it does not revert back to collagen but sets to a gel we know as gelatin.

Purpose :
To test the effectiveness  of laundry detergent brands (and their enzymes) to digest protein (in the form of gelatin)


Hypothesis:   ____________ will decompose more gelatin in millimeters than ______________.

Gelatin in 4 test tubes  Wax Pencil/ Permanent marker
3 detergent brands
Distilled water
Test tube rack

Day 1
1. Pour 5 ml of melted gelatin into 4 test tubes. Let the gelatin solidify.
2. Make 10% solutions of the five non-liquid detergents selected for testing. (Mix 10 g of detergent in 90 mL of distilled water). Label the solutions carefully and note whether enzymes are listed as a component of each.
3. Mark the top level of the gelatin with a permanent marker. Add 15 drops of each detergent solution to the top surface of the hardened gelatin in a test
tube. To one tube add 15 drops of distilled water. Label carefully.
Day 2
4. After 24 hours examine the test tubes. Notice that the gelatin has been liquefied in some tubes.  Use a ruler to measure the depth of the liquefication. Measure from the mark where the hardened gelatin started down to where it is still hard. Measure to the nearest mm. Record.
Day 3
5. Measure the depth of liquefication again after 48 hours.

Data   1 data table, 1 graph (time vs. mm. liquefied)

Enzymes listed?Liquefied After 24 hours (mm.)Liquefied After 48 hours (mm.)
Distilled Water
Detergent 1 ?
Detergent 2 ?
Detergent 3 ?



1. What is the job of enzymes?


2. Why do laundry detergents often contain enzymes?


3. Why was gelatin used in this lab?


4. How is gelatin made?


5.  Name each of the laundry detergents you used and describe the effect each one had on the gelatin.




6.  Did any of the laundry detergents contain enzymes? If so, which one(s)?


7. Was your original hypothesis correct? Explain.