The Mouldy Foods You Can And Can't Eat

When you find a bit of mould on food, it might seem like it's OK to salvage some of it because the mould doesn't cover the whole thing. That seems like the logical step, right? It turns out that's not true for a lot of foods, like bread, because the mould can hide deep in the surface where you can't see it.

Photo by Michael Bentley/Flickr.

Mouldy bread seems easy to eat around. You can see it, cut it off, and move along with your day as if nothing happened. However, since mould is a type of fungi, it has a network of roots invisible to the naked eye. That means it gets way deeper into food than you can see. Even still, with bread in particular, if the mould is concentrated on one end of a long loaf, you can still eat the other end, but any slices nearby would likely still be affected. With other foods, it depends on a few factors.

Speaking with NPR, Marianne Gravely, a senior technical information specialist for the United States Department of Agriculture, lays it out like so:

Soft fruits, lunch meats and jams also must be tossed once moldy, she adds. But for those who mourn their castaway croissants, there's some good news: Tougher foods are salvageable even after fungus has invaded. Hard cheeses, salamis and vegetables like carrots, bell peppers and cabbage have tougher surfaces, making it more difficult for a mould's roots to move through. So you can excise the mould at the surface before it ruins the food's interior. For such foods, Gravely recommends cutting the mould out with a clean knife, allowing an inch of buffer on each side of a fuzzy patch.

The fact is, most foods you should just toss. Cooked foods, yoghurt, soft fruits, breads, sliced bread or anything in a jar should get thrown away. Vegetables with harder skins can survive that mould, though personally I can't remember a single time in my life I've ever even seen mould on a carrot or a capsicum. If you're allergic to mould, it's best to skip the whole thing altogether, since it's possible to inhale those mould spores without knowing it.

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    Is mould actually harmful? What are the effects?

      I don't think it's the mould itself that's harmful but what it leaves behind (i.e its poop). I'm not a scientist though.

        I mean, mould is a type of yeast, as are bread and brewing yeast. Also, penecillin is a by product of mould. I'm genuinely curious whether there are genuine ill effects from mouldy food, or if it's just a squeamishness

          Just like some mushrooms are edible and others are deadly, mould can also be toxic but the amount you have to ingest to kill you, or upset you may be a little or a lot. Depends on species.

            Sounds like good advice, though as askvictor said, some foods (like ripe cheeses) come with a good layer of mould built in!

      Things like plants, fungi, bacteria and algae can't run away when something tries to eat them. So they evolved to incorporate poisons in their bodies to make themselves a less attractive food source. The things that eat them then evolve to cope with these poisons so they can continue eating. It's an arms race. Many insects and some animals have evolved a similar strategy.

      The net effect is that these organisms are loaded with biologically active molecules. Plants were loaded with insecticides without anyone spraying them or before anyone even knew what an insecticide was. If not, insects would have eaten them and they'd be extinct. Cultivars - edible plants that we breed to eat - have had their levels of toxins reduced systematically over time so they are (surprise) safer for humans. We even enjoy the taste of many of the toxins plants produce to kill insects!

      In addition, unlike insects we have liver that neutralizes many of these nasty chemicals. However, it doesn't neutralise every possible toxin, and, the system isn't perfect there is alway a bit of leakage into the rest of the body.

      That's the general answer, but to get a specific answer you would ask what specific mould, grown in what conditions, and how much was ingested, and who ate it. The effect may be immediate, like food poisoning or death, or may accumulate over time as eg liver or brain damage.

      In general, moulds are known to be toxic so in general we should avoid them unless they are known to be ok. I love blue cheese but I've recently worked out that it can give me migraine so, for me, it contains a neurotoxin and I should avoid it. YMMV.

    When in doubt throw it out because our bodies are a long way past being adaptable to eat mouldy or rotting food unlike humans could eat such food way back in time.

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