What You Need To Know About Moldy Food

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I’m sure you’ve lifted the lid on leftovers or unscrewed the cap on your jam jar only to find a fun little science experiment staring up at you. Oops. Looks like you’ve got yourself some moldy food. Now what?

Today I am going to explore the wide world of food mold. Why? Because mold on food is actually not a well understood issue. There are a lot of people out there cutting the mold off of a piece of bread and thinking that is a safe practice.

Let’s dive in to moldy food shall we?

A stainless steel pot of soup with mold growing on the top. A ladel lies next to the pot. There is a caption reading "what you need to know about moldy food."

Types Of Food Mold

Wait what? There are more than one type of mold that grows on food?

Just like there are hundreds of thousands of types of mold that make a home alongside us in this world, there are many types of mold that can grow on food.

The most common types of food mold are:

  • Alternaria – most common on meat and poultry
  • Aspergillus – this is one of the worst offenders when it comes to food mold. It can grow on any food under any condition and it is extremely toxigenic. Aspergillus niger shows up as the black flecks on things like onions and banana skins. It can also impact a sour lemon-like taste to things. The vivid green Aspergillus flavus, which favors peanuts and tree nuts, is down right deadly.
  • Botrytis cinereal – it is that fluffy greyish mold that devours fruit at lightening speed. It especially loves berries. Unfortunately, it is usually present on the fruit when you purchase it. This is because it has a chance to develop on the fruit while they are growing in damp conditions in the fields. Hence why berries turn so quickly.
  • Cladosporium – most common on meat and poultry
  • Fusarium verticilliodes – part of a huge genus that produces some truly terrible mycotoxins. It usually presents as that pink slimy stuff on things like corn. It can survive processing (into corn chips and tortillas) to cause things like estrogenic effects and immune suppression. Hence, Fusarium is highly regulated to try to keep it out of our food supply.
  • Geotrichum – most common on meat and poultry
  • Monilia – most common on meat and poultry
  • Manoscus – most common on meat and poultry
  • Mortierella – most common on meat and poultry
  • Mucor circinelloides – loves fruit, vegetables, and dairy especially yogurt. It can survive in your digestive track for a long time.
  • Neurospora – most common on meat and poultry
  • Penicillium chrysogenum – a common bread mold that is NOT the same species as cheese mold. This penicillium is famous for making many toxins.
  • Penicillium digitatum – it loves citrus and is responsible for that greenish mold that grows on it.
  • Rhizopus stolonifer – a blackish fuzzy mold common on bread products. It is known for getting to the bread early, eating it like crazy, and growing incredibly fast. Mold loves starch and sugar and bread offers both.
  • Sclerotinia sclerotiorum – a white mold that love cruciferous vegetables like cauliflower. It causes that dark, greasy looking spot.
  • Thamnidium – most common on meat and poultry
  • Wellemia Sebi – thick, brownish blobs that are often found growing on super sugary items like jams, maple syrup, and even ice cream toppings like caramel sauce. It is slow growing and you may never see it if you eat your jar of jam within a few weeks.

Any type of mold can grow on food but the list above are the worst offenders.

How Does Mold Grow On Food?

Mold spores fly around in the air, make a home in soil, chill out on tree branches and leaves, and generally can be found just about anywhere outdoors. Mold spores can land on fruits and vegetables being grow outdoors and begin to grow.

Indoors, spores are also floating about and easily land on the food you are preparing and storing in your home. They also make a home in food during the production process and while in storage.

Food mold feeds itself by producing chemicals that make the food break down and start to rot.  As the bread rots, the mold grows.  

Does Heat Kill Mold On Food?

Some types of mold are heat-sensitive and destroyed by heat treatments at temperatures of 140-160°F (60-71°C). On the flip side, some molds make heat-resistant spores and can survive boiling or baking. As such, it is generally understood that boiling moldy food or baking moldy food does not kill mold. Remember, while the mold may go dry from being heated, the toxins in it do not. Heating foods will not stop the mycotoxins from spreading.

What Happens If You Eat Moldy Food?

Mold can be very dangerous if eaten. The most common forms of food mold reactions are respiratory distress, such as asthma, and lung/bronchial irritations.

Some severe reactions to food molds can produce intestinal issues, damage to tissues and organs, and more. The molds themselves can produce very serious medical conditions that may require hospitalization.

What To Do If There Is Mold On Your Food

There is honestly only one thing to do if you find mold on your food. THROW IT AWAY! Do not cut off the moldy piece. If you see mold on your food that means it has already rooted inside your food. That piece of bread with a pea sized patch of mold already has mold roots / threads growing throughout it (you can learn more about that on my Mold Facts page). The strongest concentrations of the mold toxins are around these threads. Just because you can’t see mold, doesn’t mean it isn’t there. And just because you cut off the mold you CAN see doesn’t mean that is the only mold there.

Having said that, the USDA does have a slightly more relaxed stance on certain food mold. Here are a few instances where they believe it is safe to remove the mold and eat the rest of the food:

  • Small mold spots can be cut off FIRM fruits and vegetables with low moisture content. It’s difficult for mold to penetrate dense foods.
  • Mold generally cannot penetrate deep into hard cheeses.
  • Hard salami and dry cured country hams may develop mold on their exterior. This can be scrubbed off.

How Should You Dispose Of Moldy Food?

Put the moldy food in a small plastic bag or wrap it in plastic and dispose it in a covered trash container so it is out of reach of children and pets, the USDA says. I concur. Don’t just throw it in the trash and never compost moldy food.

What Foods Are High In Mold?

All foods can grow mold. Foods with high water content are the most vulnerable to visible mold growth. Fruits, vegetables, bread, and cheese are the most common foods that develop mold quickly.

There are also quite a few other foods that are high in mold (and yeast) but in general we don’t normally see the mold growth. These are:

  • Alcoholic drinks including beer, wine, cider, whiskey, brandy, gin and rum
  • Vinegar and foods containing vinegar (apple cider vinegar is safe)
  • Mayonnaise
  • Pickles
  • Soy sauce
  • Mustard
  • Relishes
  • All types of mushrooms and truffles
  • Processed and smoked meats including sausages, hot dogs, corned beef, pastrami, smoked fish, ham, bacon
  • All packaged fruit juices may potentially contain molds
  • Dried fruits

Mold isn’t the only issue for food however. Mycotoxins are a HUGE issue in our food supply and can wreak havoc on our health. The list of foods that can be contaminated with mycotoxins is extensive so I suggest you just read my post about mycotoxins here.

What About Blue Cheese and Other Moldy Foods That Are Sold In The Grocery Store?

Yes, molds are used to make certain kinds of cheeses and can be on the surface of cheese or be developed internally. Blue veined cheese such as Roquefort, Blue, Gorgonzola, and Stilton are created by the introduction of P. roqueforti or Penicillium roqueforti spores. Cheeses such as Brie and Camembert have white surface molds. Other cheeses have both an internal and a surface mold. The molds used to manufacture these cheeses are considered safe to eat.

Koji molds, including Aspergillus oryzae, are used to ferment soybeans to make soy sauce. They are also used to make vinegar, as well as fermented beverages, including the Japanese drink sake. Again, these molds are considered to be safe for consumption.

If you have a mold allergy or suffer from mold related illness I advise you to avoid foods made from molds.

How To Prevent Moldy Food

  • Purchase small amounts of food and eat it within a few days of purchase.
  • Rinse or soak all fruits and vegetables in EC3 Mold Solution before consuming. This will tackle any invisible mold, mold spores, and mycotoxins that may be lurking. You only need to use 1 teaspoon per 16 ounces of water.
  • Do not purchase any food item that has visible bruising, abrasions, or has a rotten spot.
  • Immediately freeze leftovers. Mold spores can begin to root on food exposed to air after 20 minutes. The mold will not be able to grow if the food is frozen immediately after being prepared. Mold will begin to grow if leftovers are placed in the refrigerator.  
  • When serving food, keep it covered to prevent exposure to mold spores in the air.
  • Empty opened cans of perishable foods into clean storage containers and refrigerate them promptly.
  • If you do have a food mold incident in your pantry or refrigerator, clean the area where the food was stored to prevent the spread of spores. Also check nearby items that moldy food may have touched and discard anything that came in immediate contact with the moldy food item.
  • Mold grows on wood cutting boards. Opt for a glass cutting board instead. Mold from the wood cutting board with transfer onto your food.
  • Mold spores from affected food can build up in your refrigerator, dishcloths, and other cleaning utensils. Clean the inside of the refrigerator every month. Keep dishcloths, towels, sponges, and mops mold free by promptly laundering them with EC3 Laundry Additive. You can also look into mold resistant products.
  • Follow these 27 tips to prevent mold house wide to reduce the number of air born mold spores.

Wrapping Up Moldy Food

See what I did there just now? Humor aside, food mold is no joke. It can wreak havoc on your health and also contribute to a more widespread mold issue if not dealt with properly. Practice good overall mold prevention, don’t knowingly consume food with mold on it, and always take care to dispose of it properly.

Top image is a pile of moldy strawberries. Lower image is a cheese platter with moldy cheese. Represents a guide to food mold.

Moldy Food Sources Used In This Article:

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  1. Anthony samanya says:

    Hello Jennifer, I love this article, I am interested in learning more about molds. I started reading more about molds when my wife thought we was getting sick from moldy foods whenever we visited her parents. We discovered that alot of her parent’s foods molded from over staying in the fridge. I have since devoted time to studying mold and hoping to find a solution for moldy foods some day. Is there any literature you would suggest for a good read on mold.

    1. Hi there! What specifically are you hoping to learn about? There is a lot of literature out there and I want to point you in the right direction. I do offer a recommended reading section on my website you can check out: https://moldhelpforyou.com/recommended-reading/