What you see: Mold on bread
What it is: Mold
Eat or toss: Toss. Since bread is soft, the mold could have spread into other parts of it. Even if you can’t see the mold, it could be there.
Sadly, this is a straightforward one. If you see mold on your bread, you should throw away the entire loaf.
That’s because even if you only see mold in one area, its network of roots could be penetrating deep within the soft habitat of the bread. You may not see those threads of mold, but they could be leaving behind some nasty things that could make you sick.
Airborne mold spores can trigger allergic reactions and respiratory issues, which is why you should never sniff a piece of moldy food. Some molds also produce toxins, which can make you sick in the near or long term. And if food has gotten to the point where it’s a friendly place for mold to take root, it may also be susceptible to other issues, like bacterial infection, which would further make it unsafe to eat.
So pitch the bread. But keep in mind that it’s primarily soft, moist foods that you should really worry about with mold. If you see a bit of mold on a hard cheese or a hard fruit or vegetable, for example, then it’s OK to just cut off the affected area. Such foods are too firm for the mold to cast out its spindly mold tentacles, so it’s unlikely to have penetrated past what you can see.
The U.S. Department of Agriculture breaks down what to do if you see mold on various types of food here.
Is it safe to eat moldy bread? NPR
Ask Well: Is it safe to eat moldy bread? New York Times
Molds on foods: Are they dangerous? USDA
Burning question: If you cut mould off of food is it OK to eat? - ABC (Australia)