Where's the best place to store bread? Mold growth on breadFeatured science projectScience project video

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Daily recording of data and results is required.
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Safety concerns:
Some people have mold allergies. Anyone with a mold allergy should not do this experiment. Any members of the household with mold allergy should avoid handling the moldy bread samples.


Ewwww, the bread molded again!? You may have had this happen in your home. Now your family can't eat that loaf of bread. Mold spores are everywhere and when the conditions are just right, they multiply. So, where is the best place to store bread to avoid mold growth? Is it sunny or dark places? Warm or cool places? Or perhaps it matters if it's dry or moist conditions?


If bread is stored in a cool, dry, well-lit place it will be less likely to become moldy then if stored in a warm, moist, dark location.


In this kids science project, you will see if mold (or mould) grows fastest on bread in several opposite conditions: dry or moist, warm or cool, and dark or light. You will find out what conditions cause bread to mold the fastest and what conditions help prevent that from happening.


Mold is an important part of nature, and mold is everywhere. Mold on foods can be green, white or black, and usually indicates the food is spoiled. That is because mold is part of a process called decomposition, the process of breaking down and recycling plant and animal material. The interesting thing about mold is that it is a type of fungus related to yeast and mushrooms. There are thousands of mold spores in our surroundings, and they are found everywhere - on door handles, in the shower, and even in the air. Most mold spores cause no harm unlike bacteria or viruses. In fact, mold can be very useful! One mold variety was used to create an antibiotic called penicillin, and yeasts are used to make bread and ferment wine.

Mold is a living organism. Like all living things, mold has a life cycle. In the first stage of its life cycle, mold is microscopic and dormant, or sleeping. It is waiting for the right conditions to start to grow and multiply. Mold at this stage is called spores.

anatomy of mold (mould)

When these spores settle on your bread, they grow, using the nutrients in the bread to multiply. But, mold grows best where it is dark, warm (room temperature) and moist. When the mold spores find a host (like bread) in just the right conditions (dark, warm and moist places), they grow, and grow, and grow! Trillions of mature mold spores now form a colony that we now see on the bread.

moldy bread science experiment

Can we eat the moldy bread then? If mold was used to make medicine like penicillin, we should be able to eat the moldy bread without falling sick, right? Well, there are some types of mold that won't harm most normal, healthy people (whose immune systems are functioning normally), other than the fact that mold tastes horrible. However, there are some types of mold that will actually make you sick, and it's hard to tell the difference between harmful and safe mold.

There is another factor to consider. Bacteria can potentially grow alongside the mold that is harmful. Salmonella and e coli grow well in warm, moist conditions too, and these bacteria can make you very sick. Also, some people may have an allergic reaction to mold if they have a sensitive immune system or respiratory system.

It's best to throw moldy bread away to avoid falling sick.

Scientific Terms

mold , fungus , spore , nutrients , moist , moisture , conditions


6 slices white bread (from the same loaf)

  • water
  • plastic sandwich-size zipper bags
  • 1 teaspoon
  • refrigerator
  • 1 permanent marker
  • paper/notebook
  • pencil and colored crayons, markers or pencils
  • camera (optional)


1. Label six (6) plastic sandwich-size bags with the following conditions and current date:

  • #1 dry/warm/light
  • #2 moist/warm/light
  • #3 dry/warm/dark
  • #4 moist/warm/dark
  • #5 dry/cool
  • #6 moist/cool

2. Place one (1) slice of bread into each plastic bag marked "dry", avoiding contact with any water.

3. Sprinkle three (3) slices of bread with 2 teaspoon of water. Place in the bags labeled with the word moist (#2, #4 and #6).

4. Seal all six (6) plastic bags. Make sure each is thoroughly closed.

5. Place the bags with a slice of bread in the following locations:

On the kitchen counter (where it gets at least 5 hours of natural sunlight):

In a closed, dark

kitchen cupboard:

In the refrigerator:

#1 dry/warm/light

#3 dry/warm/dark

#5 dry/cool

#2 moist/warm/light

#4 moist/warm/dark

#6 moist/cool

6. Inform everyone living in your house about your experiment. Tell them to avoid touching, smelling or eating any of the bag of bread.

7. Each day, for seven (7) days, record any mold growth. Describe the size and color of the mold colonies. Take a photograph or draw detailed, colored pictures.

8. After you record your findings on day 7, carefully throw away all bag of bread. Do not open the bags to avoid any mold spores making you sick.

9. Evaluate which conditions (you labeled your bags with these conditions) made the bread grow mold the fastest and which grew mold the slowest. Write a statement that tells the conditions in which mold grows the fastest. Write a second statement that tells the best place to store bread.


1.The bread slice in bag #4 that was in moist, warm and dark conditions should have begun to mold first and most rapidly. If it did not, and instead, the bread in bags placed on the kitchen counter began to mold first, check whether these bags were placed in such that they received enough natural sunlight during the day.

2. The bread slice in bag #5 that was in dry and cool conditions should have molded the least or not at all. Why do you think that happened? Where should bread be stored to keep it from molding?

Questions & Answers

In what conditions does mold grow the best?

If the bread does not receive enough natural light each day, it is more apt to mold as mold spores thrive in dark conditions.

Does mold grow fastest when it is dark? warm? cool? or moist?

Mold grows best in warm, moist, dark conditions. The bread in bag

Where and how should bread be stored to keep mold from growing?

Make it Your Own

In this science experiment for 2nd to 4th graders, you placed one type of bread in contrasting warm and cool areas, dark and light areas, and you also added moisture. Here are some questions to think about to make this experiment your own.

Does keeping bread frozen help keep mold growth from happening? Add a frozen sample to compare.

Do certain types of bread grow mold faster than other types? Try putting moistened white, whole wheat and sourdough bread in a warm, dark place to see which type grows mold the fastest.

What other types of food tend to mold? Put an orange, an apple, jelly, lunch meat, and cheese in a dark, warm place and compare it to the same food kept in the refrigerator. Be sure to put each in a container to avoid mold spores (and the smell) from making anyone sick.


Florida Solar Energy Center (2007). Mold Growth. Retrieved on November 11, 2013 from http://www.fsec.ucf.edu/en/consumer/buildings/basics/moldgrowth.htm