The term ‘food mold’ is often associated with ‘danger’. But not all molds on food are harmful. Some are even essential to the production of the food we eat every day, such as cheese, miso, and tempeh.
But how can you tell the difference between harmless mold and dangerous contamination? And how can you prevent them from appearing on your food? When is mold harmful to eat?
This article gives you all the information you need to make the right choices and protect your health while reducing food waste.
What Is Mold?
Molds are microscopic fungi that develop in the form of filaments called mycelium. They often appear as fluffy or powdery spots of different colours. Mold on food can be white, green, blue, orange, or black…. There are many types of food mold, more than you might think!
Which Molds Are Safe to Eat?
✅ Aspergillus oryzae: used in the fermentation of miso and soy sauce.
✅ Penicillium roqueforti: gives Roquefort its unique flavour.
✅ Rhizopus: essential for fermenting tempeh.
✅ Penicillium nalgiovense: used for maturing certain salamis and hams.
So yes, molds can be safe to eat! Molds are the source of many fermented foods with recognized benefits for digestion and immunity.
Why Are Some Molds Harmful?
Some food molds are dangerous because they produce mycotoxins: toxic substances that may be harmful to health. According to a scientific study (ref.), prolonged exposure or exposure to high doses of these substances can lead to the following symptoms of mold poisoning:
- Digestive problems (nausea, vomiting, etc.)
- Weakening of the immune system, fatigue.
- Harmful effects on the liver and kidneys.
- Hormonal disorders.
When Should You Exercise Caution?
Here are the signs that should prompt you to be vigilant:
- Presence of coloured hairs or spots (mycelium).
- Unpleasant or pungent odour.
- Slimy texture.
📌 Mycotoxins are invisible and are very difficult to eliminate during cooking. So if you eat moldy food, you may experience these signs of food poisoning. (ref.)
When Should Moldy Food Be Discarded?
When mold appears on food, the appropriate reaction will depend on its texture and composition. Here are the best practices to adopt (ref.):
🚫 Discard immediately
These foods can be contaminated in depth, even if mold appears localized.
- Soft fruit and vegetables (tomatoes, cucumbers, peaches…)
👉 Mold on fruit poses a hazard, quickly seeping throughout the flesh. - Soft cheeses (brie, camembert, fromage frais…)
👉 Spores spread inside without being visible. - Bread and pastries
👉 Mold spores spread throughout the crumb, so don’t eat moldy bread, as it is harmful. - Jams, sauces, and compotes
👉 High risk of production of dangerous toxins.
✅ Can be eaten after taking some precautions:
- Firm fruit and vegetables (cabbage, carrots, bell peppers, …)
✂️ Cut at least 2.5 cm/1 inch around the affected area, as contamination remains on the surface. - Hard cheeses (Comté, Parmesan…)
✂️ In this case, it is safe to cut mold off cheese. Remove the moldy area generously, as the dense texture prevents the mold from penetrating deeper. - Dry-cured hams and meats
✂️ Scrape off surface mold before eating. These products often develop harmless surface mold.
⚠ When in doubt, don’t take any chances! Some molds are harmless, but others can produce toxins that are dangerous to your health.
How Can I Prevent Mold Growth?
Storage and Hygiene
- Store your food in airtight containers to limit exposure to air and moisture.
- Clean your fridge and cupboards regularly to avoid cross-contamination.
- Avoid excessively damp environments, which are conducive to mold growth.
Fermentation, a Natural Solution Against Mold!
Lacto fermentation is a natural and effective way of preserving food by preventing mold from proliferating (ref.). Several parameters come into play:
- An acidic environment: Lactic acid bacteria lower the pH, making the environment inhospitable to molds.
- A protective effect: The good bacteria take over and prevent undesirable microorganisms from developing.
- Natural antifungal compounds: Some bacteria produce substances that directly inhibit mold.
Key Points to Remember
- Not all molds on food are harmful, but some produce harmful toxins that can lead to poisoning.
- To identify toxic contamination, rely on your senses: contaminated food will have a suspicious colour, a pungent smell, and/or an unusual texture.
- It’s best to throw away any moldy food you’re not sure about, especially bread, fruit, or preparations with a high water content.
- Fermentation, good hygiene, and proper storage are your best allies in preserving food and limiting the spread of mold!
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