Do Hand Soaps and Sanitizers Prevent the Growth of Bread Mold? (page 2)

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Author: Erin Bjornsson
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10 Food Experiments for Kids


Your results will vary, but you should notice the following patterns:

  • The open bags should have grown more mold than their sealed counterparts.
  • Damp bread should have grown the most mold.
  • The sealed and toasted specimen sprayed with hand sanitizer should have grown the least mold.
  • In general, toasted bread will have grown less mold than untoasted bread.
  • Soap will not have been as effective in preventing mold growth as then hand sanitizer, but it will have prevented more growth than the wet bread and the control group.


Molds need water and nutrients to grow. The wet, untoasted bread specimens will have grown the most mold because they fit these conditions the best. The high heat produced by toasting dries out and breaks down many of the nutrients in bread, so the mold will have less water and fewer nutrients to feed on.

The bags that were left unsealed for a week will have grown more mold than the closed bags because of how mold travels. Molds reproduce by releasing spores, which are the fungi-equivalent of seeds. Spores can travel easily through the air because they are so small. Their spores can often travel even farther by attaching to clothing or the fur of animals, and some can survive extreme conditions like the heat of a desert or the cold of Arctic regions. (Remember when we asked you why we’d want to put on gloves for this experiment? Wearing gloves prevents contamination of the bread by any germs we may have on our hands. Wearing gloves makes sure that mold is introduced to the bread naturally.)

The active ingredient in hand sanitizer is Ethyl Alcohol. Ethyl alcohol can kill bacteria directly, but can also prevent fungal growth because alcohol is a good drying agent. This means that alcohol sucks up the moisture that the mold uses to reproduce.

Many soaps do not contain alcohol, but they do contain other chemicals like acids and sulfates which can act as drying agents. Soap may also directly kill fungi if it contains certain antifungal chemicals. If you want to get serious with this project, do some research on the types of chemicals found in whatever brand of soap you used, and see if any of them are classed as antifungals!

There are four major types of bread mold. You may grow one, or you may grow them all. Which types of mold did your bread grow?

  • Rhizopus – gray or black, fuzzy
  • Penicillium – grayish green to white            
  • Aperaillius – green-blue to brown, grows fast in large clumps            
  • Fusarium – brownish or reddish, very fast growing

We may not want to eat mold, but mold can be a beautiful thing! Many molds are used to produce life-saving medicines, or clean up toxic oil spills from the environment. They are great for many biological and engineering purposes because they are simple and reproduce quickly.

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