It’s lunchtime, your stomach is growling and you’ve decided to make a sandwich. But as soon as you head to the pantry and open the bread bag, you see it: a whitish, greenish spot. Ugh — it’s mold.

Some foods are not worth saving once the first hints of mold appear, according to the pros. Some foods can harbor hidden mold even when they look fine. Items like bread, soft cheeses, berries, and ...