Many laundry detergents contain special enzymes that help to get laundry cleaner. Some of the most commonly used enzymes are: proteases to digest protein based stains, a-amylase to digest starch based stains, and lipases to digest fat or oil based stains. Other enzymes used in some detergents are Guardzyme (a peroxidase) to inhibit dye transfer and Carezyme to remove the fuzz that builds up on cotton clothes.

This laboratory activity is intended to allow students to investigate the effectiveness of enzymes in laundry detergents.

Materials:

6 – 6″X6″ pieces of cloth

all from the same original piece of material

all with a stain from the same source

5 – numbered samples of liquid laundry detergent (brands unknown)

1 – timer, watch, or clock with a second hand

6 – small containers to wash the cloths in

6 – plastic spoons

1 – permanent marker

Procedure:

1. Label each cloth with one of the detergent sample numbers. Label the last cloth with a C for control.

2. Place an equal amount of each detergent on each cloth and leave the last cloth untreated as a control.

3. Rub the detergents into the stains and then handwash each cloth separately, but in the same temperature water and for the same amount of time. For example, fill each container with very warm water from the tap, add one cloth to each, and stir or agitate the soaking cloths for 5 minutes.

4. Record your water temperature (hot, warm, or cold) and wash time in the results section.

5. Rinse each cloth thoroughly in cool tap water and lay them out for observation.

6. Fill in the results table for each cloth by circling the number that best shows how much stain was removed (1 meaning no stain was removed and 10 meaning all of the stain was removed).

Questions:

Why is a control needed?

Why should each cloth be washed separately?

Why should the time and temperature be kept constant?

Results:

What type of cloth was used? (cotton, poly/cotton blend, etc.)	______________________
Was the cloth new or used?	______________________
What was used to make the stain?	______________________
What temperature was the wash?	______________________
How long was each wash?	______________________

Detergent	Stain Removal
	No Stain Removed			Some Stain Removed			All Stain Removed
Control (no detergent)	1   2   3   4   5   6   7   8   9   10
1	1   2   3   4   5   6   7   8   9   10
2	1   2   3   4   5   6   7   8   9   10
3	1   2   3   4   5   6   7   8   9   10
4	1   2   3   4   5   6   7   8   9   10
5	1   2   3   4   5   6   7   8   9   10

Interpretation:

Which detergents worked best?

Which detergents worked worst?

Considering the source of the stain, make an educated guess as to what type of enzyme(s) each detergent may contain? (none, protease, lipase, &/or amylase)

Would these detergents give the same results with different types of stains? at different temperatures? with different wash times?

Would different results be expected with powdered detergents? Explain.

Get the list of the brand names of the laundry detergents that were used from the instructor. Which detergents have enzymes?

Instructors Notes For Enzymes & Laundry Detergents