Effect of Mold Growth on Various Types of Cheese
The Experimenter

Researched by Whitney B.


The first purpose of this experiment was to compare the mold growth on Mozzarella, Colby jack, pepper jack, and cheddar cheese.

I became interested in this idea when I went to get some cheese for dinner and it had mold all over it.

The information gained from this experiment could help people decide what kind of cheese to buy for mold resistance. This would be valuable to hunters, back packers, and those who live far from a store. People who run restaurants or other big kitchens (like schools or hospitals) would also be interested. People who sell or distribute cheese would also want to know. 


My hypothesis was that mozzarella cheese would support the most mold growth of the three types.

I based my hypothesis on the World Book Encyclopedia article, “Cheese”, by Robert T. Marshall, “softer cheese will support more mold growth”.


The constants in this study were:
  • The brand of cheese
  • The size of the cheese squares tested
  • The temperature the cheese is stored
  • The container cheese is held in during the experiment
  • The type of mold used to inoculate cheese

The manipulated variable was the type of cheese.

The responding variable was the amount of mold grown.

To measure the responding variable I used a transparent plastic grid marked with square centimeters to measure the mold growth daily.

5cm x 5cm x 1cm of Mozzarella cheese
5cm x 5cm x 1cm of cheddar cheese
5cm x 5cm x 1cm of Colby jack cheese
5cm x 5cm x 1cm of Monterey jack cheese
Felt pen
Transparent plastic sheet with 1cm x 1cm grid
Rubber glove
sterilized knife
2 vials
Rhizopus stolonofer +
9in x 12in aluminum pans
Cutting board


1. Wash hands
2. Wash materials with Rubbing Alcohol
3. Cut 4 pieces of wax paper 17cmx23cm and place in four “9inx12in” aluminum pans.
4. Cut the cheddar cheese into six slices, 5cmx5cmx1cm.
5. Put on lab coat, goggles, and rubber gloves.
6. Add water to the mold spores purchased from a biological supply house and make a mold suspension with water.
7. Dip the cheese into the mold suspension.
8. Place cheese on the wax paper.
9. Label the cheese slices “trial one” through “trial six”.
10. Place a 6cmx8cmx1.5cm-wet sponge in the center of each pan to avoid dehydration.
11. Cover tightly with plastic wrap.
12. Store cheese at 22 degrees in a safe place at school.
13. Repeat steps 1-8 for each of these other groups, Mozzarella, Colby jack, and Monterey jack cheese.
14. Measure the mold growth on all the cheese with the transparent grid every day for one week.
15. Record in data table.


The original purpose of this experiment was to compare the mold growth on Mozzarella, Colby jack, pepper jack, and cheddar cheese.

The results of the experiment were that the highest average amount (on the final day) of mold growth was 6 sq cm on mozzarella cheese. The lowest amount was pepper jack cheese; it only had 0.3 sq cm of mold growth.

See my table and graph. Click below.



My hypothesis was that mozzarella cheese would support the most mold growth of the three types.

The results indicate that this hypothesis should be accepted; mozzarella cheese was first to mold and had the most mold growth.

Because of the results of this experiment, I wonder if the results would be different if the cheese was stored at room temperature, 3 degrees Celsius.

If I were to conduct this project again I would have a lot more trials, run my experiment for more days, and I would use more types of cheese. I would also keep everything more accurate.


Mold is a fungus that grows on organic foods such as cheese when in bad storage or moist areas.

Mold is a term used to describe a type of fungus that is often fuzzy looking. It mainly grows on organic materials and in damp conditions. Mold lives almost anywhere on land and water. Some molds feed on plants and decaying animals. There are over 100,000 species of mold, about 1,000 are found in the United States.

How Does Mold Grow
Mold produces tiny spores. To reproduce, mold spores float through the air in- door and outside. When a spore lands on a damp spot it begins to grow. Indoor spores can grow on wood, paper, fabric, carpet, food, and other organic items. All mold needs water to grow. Mold can grow anywhere there is water, high humidity, or dampness.

Mold and Human Health
Mold is a natural part of our environment; but human health problems may result when exposed to too much mold. Inhaling too much mold may cause illness, asthma, infections, allergic reactions, or it may bring a toxic effect from certain chemicals in mold spores.

Parts of Mold

Except for one-celled fungi the main part of mold is thousands of thread like cells called hyphae. Hyphae form a tangled mass called mycelium. In most fungi mycelium grows beneath the surface on the material of what it feeds on.  Mold lacks chlorophyll and does not make its own food; instead it absorbs nutrients from its surroundings.

The Good and Bad About Mold

Some mold can be very bad for people. It can cause diseases such as ringworm. Ringworm is when a certain mold spore falls on a persons’ or animal’s body and begins to grow. There is another type of mold that cures ringworm. Mold will also spoil food. Even though mold causes diseases and spoils food it also has its upsides. Mold decomposes dead animals, leaves, plants, and fallen trees. Medicine is made from some kinds of mold. 

Cheese is a healthy food that is made from milk. Cheese originated about four thousand years ago by a nomad tribe in Asia. Through years of knowledge, cheese making spread to Europe. Cheese making came to America in 1611. Settlers from James Town got cows from England for milk. Several years later people learned how to turn perishable milk into solid food so it won’t spoil as easily.

How to Make Cheese
Cheese makers inspect the milk and remove the solid substance by processing the milk for clarification. The milk goes into the pasturizer to kill the bad bacteria. The milk gets put into metal cans that hold eight thousand to thirty-five thousand pounds of milk. It takes ten thousand, five hundred pounds for one thousand pounds of cheddar cheese. After the milk is processed it is treated to form a custard-like substance called the curd. The curd has liquid in it called whey. The whey is taken out before the cheese is made. Cheese makers make the curd by heating the milk from 86 degrees F to 96 degrees F. Aging or curing the cheese gives it flavor and texture. Cheese is aged in a storage or warehouse that has a controlled temperature. Aging time varies between different cheeses. The longer the cheese is aged the sharper the flavor is. After the aging process it is packaged in all different shapes and sizes. Some are packaged as a block or brick shape and others are cut or grated. No matter how the cheese is cut it is all sealed in foil or plastic wrap. Most cheese in the United States is made into process cheese, which is a blend of natural cheeses. Process cheese keeps better then natural cheese and melts more evenly when used in cooking. Most processed cheese is made with two or more kinds of cheese.

Types of Cheese
There are many types of cheese; each kind is separated into one of the following groups; soft, semi soft, semi hard, or hard. Brie, Camembert, cottage, and cream cheese are considered soft cheeses. Limburger and Roquefort are semi soft. Cheddar, Edam, and Swiss are all semi hard cheeses. Parmesan, Roman, Sapsago are hard cheeses. These are only a few of the many types of cheese. There is Mozzarella, American, Colby jack, Pepper jack, Monterey jack, and much more.

In conclusion mold has a toxic effect on people and food such as cheese, but it’s not all that bad. There are types that can be a very helpful medication. Cheese originated in America in the 1600’s and should be a delicious part of society for many more years to come.

Ammirati, Joe F. “Mildew,” World Book Online. November 10, 2004

Ammirati, Joe F. “Fungi,” World Book Encyclopedia, 1998

Ammirati, Joe F. “Mold,” World Book Encyclopedia, 2002

“Cheddar” Cheese Description. December 8,2004. <http://cheese.com/Description.asp?Name=Cheddar

Hutjens, Michael F. “Casein,” World Book Encyclopedia, 1998

Sachs, Jessica Snyder, New Book of Popular Science volume 4, Portland, Oregon: Timber Press, 1991, pp. 36-37

Marshall, Robert T. “Cheese,” World Book Encyclopedia, 1999

“Monterey jack” Cheese description. December 8, 2004. <http://cheese.com/Description.asp?Name=Monterey20%jack>

“Mold” Mold and Human Health. December 8, 2004 <http://www.epi.state.nc.us/epi/oii/mold/>

“Mold” Facts about mold. December 8,2004. <http://www.nyc.gov/html/ei/eimold=html

Reinhard Young Scientist, Living World-Plants, Chicago, IL, ZEFA Picture Library


I would like to thank the following people for helping make my project possible:
  •   My mom for transportation when I stayed after school to work on my project.
  •   Taylor for helping me find information on my topic.
  •   Mrs. Helms for helping me understand some of the information I didn’t know.   
  •   Mr. Newkirk for helping me set up my project and run my experiment.

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