What Makes Bread Get Moldy?
Mold is a type of fungus plant. It does not make its own food, but lives off some of the foods we like to eat. Bread is one of them. Molds grow from tiny specks called spores. These spores are too small for us to see without a microscope. They are carried about by air currents.
When the mold spores land on moist food, they quickly grow into fuzzy green or gray patches of mold. Molds grow in every color imaginable. (Look for black bread mold on old bread.)
When the little mold plants have grown, they send out more tiny spores into the air. So when bread has become moldy, you know that mold spores have landed there.
Mold will not only live and feed on bread, it will also reproduce there. This is why you see bread mold spread throughout your loaf if you let it sit there long enough. Mold reproduces as long as it has a nutrient source – sometimes it can double in size in an hour’s time.