When you see a spot of mold on bread, you are just seeing the tip of the iceberg so to speak, because mold has long threadlike roots that invade the food “and you might not be able to tell how far it’s gone,” said Marianne H. Gravely, an educator with the United States Department of Agriculture’s Food Safety and Inspection Service.
The U.S.D.A. recommends discarding bread and other baked goods with mold because the microscopic fungi can cause allergic reactions and respiratory problems in some people. A few molds, under certain conditions, may produce hazardous substances called mycotoxins. The worst of these, aflatoxins, may cause liver cancer and are found primarily in peanuts and corn during harvesting and storage. Their presence is monitored by government agencies.
If you want to preserve some of the bread, Ms. Gravely said, “cut away a big section surrounding the mold with a healthy margin around it to make sure you got all of it.”
But check the whole bread loaf carefully as there may be more mold you haven’t noticed in other spots. Mold is an indication the bread has probably been stored for too long and is “past its prime,” Ms. Gravely said. Foods that are moldy may also have bacteria that is invisible to the naked eye.
The exceptions are hard salami, which you can scrub the mold off, along with hard cheeses and firm fruits and vegetables, which should have a large section around the mold carved off and discarded. (Molds used in the manufacturing of cheese like Roquefort and Brie are safe to eat.)
Never sniff mold that you see on food – that can lead to respiratory problems if the mold spores are inhaled. Wrap moldy food in a bag or in plastic before throwing it out and discard it in a trash can with a lid. Clean the area where the item was stored and check other food items nearby to see if they have been contaminated, since molds can spread easily through the air or by contact with contaminated foods.