Mold growth on food is an alarming sign that often raises concerns about safety. While moldy food might seem harmless on the surface, it can pose significant health risks depending on the type and extent of contamination. Understanding how molds behave and the toxins they may produce is crucial in determining whether food should be salvaged or discarded.
Molds are microscopic fungi that thrive on organic matter, including plant and animal-based foods. They reproduce by releasing spores into the air, which can settle on food and grow under suitable conditions. Mold structures include threadlike root systems that penetrate deep into the food, a stalk that rises above the surface, and spores that form at the tips. These spores are often what give mold its distinctive fuzzy or colored appearance.
Unlike bacteria, which are single-celled, molds are multicellular and can often be seen with the naked eye. However, the dangerous part lies beneath the surface—mold roots can extend far into the food, carrying toxins with them that are not always visible.
Not all molds are dangerous, but some can cause allergic reactions and respiratory issues, especially in sensitive individuals. More critically, certain molds produce mycotoxins—toxic compounds that can lead to serious health issues if ingested. One of the most notorious mycotoxins is aflatoxin, a potent carcinogen found mainly in grains, nuts, and some produce. Aflatoxins have been linked to liver damage and are a major concern in food safety worldwide.
Mold presence on food is not always limited to the surface. In many cases, especially in moist or soft foods, the mold’s root system and associated toxins may spread throughout the product. Even if you cut away the visibly moldy part, invisible contaminants may remain.
Molds are incredibly adaptable. While they thrive in warm, humid environments, many molds can survive in the refrigerator and even in salty or sugary foods. This means mold can grow on items like cured meats, jams, jellies, and cheeses stored in the fridge. Moreover, mold spores are airborne and can spread rapidly from one item to another, especially in enclosed spaces like pantries and refrigerators.
In the U.S., regulatory agencies such as the FDA and USDA monitor food products for harmful molds and mycotoxins, especially aflatoxins in peanuts and corn. Despite these controls, it’s important for consumers to remain vigilant, as mycotoxins are considered unavoidable contaminants in some crops.
To minimize mold growth, cleanliness is key. Regularly cleaning your refrigerator, using airtight containers, and maintaining low indoor humidity (ideally below 40%) can help prevent mold proliferation. Utensils, dishcloths, and sponges should also be kept clean and dry to avoid spreading mold spores.
Not all molds are harmful. Some are intentionally introduced during food processing to produce cheeses like Roquefort, Brie, and Camembert. These molds are safe to eat and contribute to the flavor and texture of the cheese. However, if a mold appears that wasn’t part of the cheese-making process, the product should be discarded.
When dealing with moldy food, safety comes first. Never sniff moldy items, as spores can trigger respiratory problems. Foods with high moisture content—such as cooked meats, casseroles, soft cheeses, yogurts, and soft fruits—should be discarded entirely if mold is present, as the mold may have spread deeply. Hard foods with low moisture, like hard cheese and firm vegetables, may sometimes be salvaged by cutting off at least one inch around and below the moldy area, ensuring the knife doesn’t touch the mold itself to prevent cross-contamination.
Breads, baked goods, and nut butters are porous and can be deeply infiltrated by mold, making them unsafe to consume once mold appears. Moldy jams and jellies, even if they seem mostly intact, can harbor mycotoxins and should be thrown away rather than salvaged.
To protect food from mold contamination:
While some molds are useful and even necessary in food production, many are harmful and can pose serious health risks. Recognizing when food is unsafe and handling it correctly can prevent foodborne illness and keep your kitchen environment safe. When in doubt, it’s best to follow the rule: “When mold is in doubt, throw it out.”