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What to Know About Molds on Food

Reviewed by Poonam Sachdev on November 10, 2021

Mold is a type of fungus that causes food spoilage. It has a nasty taste and texture. Sometimes, mold may have white or green fuzzy spots, especially when it's growing on bread. 

Mold may only appear on the surface, but it has roots underneath. Even if you take the top part of the mold off, its roots will still be in the rest of the food item. 

What are Molds?

Molds are fungi, most of which are visible to the human eye when they form groups. Scientists don't know the exact number of mold types present on Earth. There likely are more than 300,000. Most molds are thread-like organisms that produce spores. 

Air, insects, or water may transport these spores from one place to another. While bacteria are single-celled, molds have multiple cells. Under the microscope, the body of a mold has: 

  • Roots invading the food on which the mold is growing 
  • A stalk that resembles a tree's trunk
  • Spores, resembling flowers, that grow on the end of these stalks 

It's these spores that give each mold a characteristic color.

What Are the Best Conditions for Mold Growth?

Mold grows best in humid and warm environments. Mold can survive on foods with a high acid content, such as fruits, pickles, jams, salt meats, and tomatoes. Some types can also grow in a refrigerator.

Mold can start growing on your food well before you buy it.  It can grow during the food processing or production processes, like harvesting and storage. 

Research shows that foods with preservatives in them are less prone to mold growth. These foods also have a lower likelihood of bacterial growth. Fresh food that has a high water content is more susceptible to mold growth. 

Is Mold Dangerous?

Some molds are dangerous because they can cause respiratory problems. Some types may also lead to allergic reactions. A few molds also produce poisons, called mycotoxins, that can make you very sick. 

Mycotoxins are produced by molds present on nut crops and in grain. But they could also come from molds growing on fruits, like apples. Another type of toxin, called aflatoxins, can even cause death.

What Happens If You Eat Moldy Food?

Some foods are naturally moldy. For instance, blue cheese has a moldy appearance and taste because it comes from a strain used to make the penicillin antibiotic. Similarly, country-cured ham also has mold growing on it since it goes through a long drying and curing process. However, the USDA recommends you use a stiff vegetable brush to scrape off the mold before eating the ham.

Foods that have molded because of age or because they weren’t stored correctly include bread, fruit and jarred sauces.

If you ingest mold, you may have no reaction. On the other hand, some types can be very toxic, causing an instant allergic reactions. Other types do not cause any harmful reactions. 

You may be tempted to cut around the mold and eat the rest of the food. This is not a good idea. If there's mold on food, its roots are inside. And, there's most probably bacteria growing there, too. While mold is visible, you can't see bacteria with the naked eye. 

If you see fungus on food, it's best to discard the food item. 

How Do I Prevent Mold on Food?

Mold needs a specific type of environment to thrive. If you prevent the formation of this environment, you can stop mold growth. 

  • Keep the food covered when you're serving it. This will prevent the mold spores in the air from contaminating your food. 
  • Cover foods with plastic wrap if you want to keep freshly cut vegetables and fruits moist. Do the same with salads. 
  • Don't keep half-used cans of perishable food items in the fridge. Mold can also grow on foods in your refrigerator. Instead, put the leftover food in an airtight container and refrigerate it. 
  • Don't leave perishable items uncovered in your refrigerator for over two hours. 
  • Don't keep leftover food in the fridge for more than three or four days. Otherwise, there's a higher risk of mold growth. 

Since food molds are everywhere, including the air around us, there's really no way to remove them. Instead, you can prevent the growth of fungus on food and practice safe cooking. 

Show Sources

SOURCES: 
Cleveland Clinic: "What Happens if You Accidentally Eat Moldy Food?."
Food Safety and Inspection Service: "Molds on Food: Are They Dangerous?"
Microorganisms: "Antifungal Microbial Agents for Food Biopreservation-A Review."
University of Minnesota Extension: "Are molds on foods dangerous?"
U.S. Department of Agriculture: "How can you protect food from mold?"
USDA: "What should I do about mold on a country ham?"

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