When you find a bit of mold on food, it might seem like it’s okay to salvage some of it because the mold 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 mold can hide deep in the surface where you can’t see it.
Moldy 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 mold is a type of fungus, 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 mold 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 mold’s roots to move through. So you can excise the mold at the surface before it ruins the food’s interior. For such foods, Gravely recommends cutting the mold 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, yogurt, soft fruits, breads, sliced bread, or anything in a jar should get thrown away. Vegetables with harder skins can survive that mold, though personally I can’t remember a single time in my life I’ve ever even seen mold on a carrot or a bell pepper. If you’re allergic to mold, it’s best to skip the whole thing altogether, since it’s possible to inhale those mold spores without knowing it.