How to Make Mold on a Bread: 10 Steps

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How to Make Mold on a Bread: 10 Steps
How to Make Mold on a Bread: 10 Steps

Want to experiment with fungus for school? Growing mold on bread is not only a good science fair project, it's also an activity that will teach you how to keep bread fresh at home. With a little humidity, heat and time, you'll soon have a green sandwich that will impress and disgust everyone.


Part 1 of 2: Growing mold

Make Mold Grow on Bread Step 1

Step 1. Gather the necessary materials

To grow mold on a loaf of bread, you will need: a slice of bread (any type), a plastic zipper bag, a spray bottle, and water. As much as any type of bread will do, packaged loaves contain preservatives that delay the appearance of mold. Fresh bread will give quicker results.

  • The spray bottle isn't exactly necessary, but it's a great way to evenly coat the bread with a thin layer of water.
  • Fill the bottle with water before starting the experiment.
  • In the absence of a plastic bag, use any clear container with a lid. Transparency is important for mold observation, while the lid is important for mold containment. Any plastic or glass pot should do, but be aware that you will need to discard the container at the end of the experiment.
Make Mold Grow on Bread Step 2

Step 2. Sprinkle water on the bread

The idea is to form a thin layer of liquid over the dough, without soaking the bread. A single spray is enough to stimulate mold growth. Other options to keep the environment moist:

  • Place a wet paper towel inside the plastic bag next to the bread.
  • Pour some water over the bread.
  • Sprinkle the water on the bag instead of the bread.
Make Mold Grow on Bread Step 3

Step 3. Close the container

Place the damp bread in the plastic bag and close it tightly. The idea is to keep the seal until the end of the experiment, to avoid exposure to mold spores that will grow on the bread.

People who have allergies should not do this experiment as it can cause problems

Make Mold Grow on Bread Step 4

Step 4. Store the bread in a moist, slightly warm place

Mold thrives most in humid, relatively warm environments, so find the ideal spot in your home for the experiment. As you have already moistened the dough, just find a warm place.

Mold is a heterotrophic substance, meaning it does not need sunlight to feed. It feeds on bread, breaking down starch into smaller sugars. That's why mold tends to develop in dark, damp environments

Make Mold Grow on Bread Step 5

Step 5. Observe mold growth

Make daily checks, monitoring the growth of mold on the bread. Depending on the type of bread used, mold should start appearing after the fifth day; in most cases it is normal for mold to be visible between the seventh and tenth day. Remember that fresh breads mold faster than packaged breads.

If the bread becomes dry, start again with a more moist dough. Do not add more water to the bread as opening the container can release mold spores into the air, causing allergies or respiratory problems. Some spores contain mycotoxins capable of causing neurological problems

Make Mold Grow on Bread Step 6

Step 6. Dispose of the bread correctly

At the end of the experiment, throw the bread in the trash, still in the closed bag. Do not open the container in which you stored the bread, or you could end up releasing mold spores into the environment, causing possible health problems.

Wash your hands after handling the plastic bag

Part 2 of 2: Experimenting with Different Growing Conditions

Make Mold Grow on Bread Step 7

Step 1. Prepare multiple samples

To analyze mold growth under different conditions, you will need more than one sample. Moisten as many loaves as needed for testing, placing one in each separate bag.

  • For example, if you want to analyze three different temperatures, prepare three samples.
  • Make some predictions before the experiments. Make hypotheses as to how fast the mold will grow under each of the test conditions and write them down in a small notebook to compare the results later.
Help Back Problems With Pilates & Yoga Step 3

Step 2. Vary the amount of water in each would to see how moisture affects mold

The other conditions (lighting and temperature) must be the same, so that it is possible to analyze only the effect of water on mold growth. Prepare one slice without water, one slightly moistened and one soaked.

Check the samples daily to see if mold growth occurs differently between them

Make Mold Grow on Bread Step 8

Step 3. Place the bread samples at different temperatures to see what effects it has on mold

To analyze mold growth at different temperatures, store one sample at room temperature, one in the freezer, and one in the refrigerator.

  • To minimize variation, it is good to use the same amount of water on all pieces of bread and store the room temperature sample in the dark, as cooled samples will already be in the dark.
  • Check the samples every day to see which mold grows the fastest.
Make Mold Grow on Bread Step 9

Step 4. Store samples in locations with different lighting levels to analyze the effect of light on mold

If you want to test whether or not lighting plays a role in mold growth, place one bag in a dark room and the other in a well-lit place.

  • To minimize variations, make sure the temperatures of the two environments are similar. Also use the same amount of water for both loaves; otherwise, it will be difficult to know whether the difference in growth rate is due to lighting, water or temperature.
  • Analyze samples daily for differences in growth rate.


  • Wash your hands after completing the experiment.
  • At the end of the experiment, throw the bread in the trash, still in the closed bag.
  • Do not open the bag or let anyone else eat the bread.
  • If the bread gets dry, it will end up hard and tasteless, not moldy.


  • Not eat, smell or even take the bread out of the bag. Mold releases small spores into the air that can trigger allergies in people and spread mold around the environment, contaminating unwanted things.
  • Penicillin grown in bread cannot be used to treat illnesses or infections.
  • Bread mold is quite toxic to dogs, so don't let your pet come into contact with the dough or anything that has touched the bread.

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