Science experiment on white vs. wheat bread mold

Updated July 18, 2017

If you have ever left bread sit around for too long, you probably have experience with bread mould. Several species of mould grow on bread. These moulds occupy the air around us. Bread mould takes nearly no effort to grow and is a favourite science project for school science fairs.

Mold Basics

Mold is a fungus, not a plant. Fungi do not photosynthesise sunlight. They must feed on something for survival, like bread. Many mushrooms consume rotting wood, for example, and there are even fungi that feed on flesh. Molds emit spores -- somewhat like seeds -- and these travel through the air. Mold seems to grow out of nowhere. That is because the microscopic mould spores drift all around us, just waiting to find something damp and delicious to latch onto, like bread. Mouldy bread is a common problem, and one that bakers through the centuries have had to deal with. Many large bread manufacturers mix chemicals and other preservatives into their breads to slow the growth of mould.

White Bread and Wheat Bread

There are some major differences between white bread and wheat bread. Wheat bread is made out of unrefined whole grains. Bread labelled "white wheat bread" is still wheat bread, but it is made with another type of grain. White bread, on the other hand, is baked with refined grains. The refining process removes certain parts of the grain as well as some important nutrients. The nutritional quality of these two types of bread is different, for humans and mould.

Experimenting with White and Wheat Bread

You can conduct a simple experiment that illustrates how the different ingredients of white bread and wheat bread affect mould growth (if at all). Take a slice of wheat and a slice of white bread and put them on separate plates. Using a teaspoon, add a little water to the bread so they are damp, but not soaking. Place the plates in a warm, dark, out-of-the-way location (such as the top of the refrigerator). Every day, add a little more water so that the bread stays damp. Note how long it takes bread mould to grow on each slice of bread.


Since bread mould is so easy to grow, this experiment is open for tinkering. Try seeing what happens when you put a slice of each in the refrigerator versus a windowsill. Place different samples in the dark and others under light. You can also experiment with bread baked fresh from your own oven. Make white bread with plain, white flour and wheat bread with whole wheat flour. See how home-baked bread compares with preservative-laden, store-brought bread. This experiment can be about more than just mould. It touches on hot concepts like food preservation and chemicals in our bread, as well.

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About the Author

Based in Chicago, Barry Eitel has been writing about the city and the arts since 2005. He has written for several websites, including Chicago Theater Blog and PlayShakespeare. Eitel has a Bachelor of Arts in philosophy from Loyola University Chicago.