There are two types of cheese molds: desirable and harmful. Desirable molds create the crust on brie, camembert, and other soft cheese - and the veinlike mold inside Roquefort and other blue cheese. Without these beneficial molds, the cheese would not properly ripen or taste as good.

Harmful molds are virtually everywhere and attack both soft and hard cheese. Their high toxicity level can make you sick, or worst. They normally arrive airborne, landing uninvited on the cheese at the factory, on the truck, at the store, or in your home. These harmful molds quickly multiply on the cheese surface and bore into the cheese with their threadlike filaments called hyphae.

A contaminating mold's hyphae penetrate considerably faster in a soft than a hard cheese, owing to less physical resistance and more moisture, which aids the mold's growth. Hyphae are not always easy to spot, so it is wise to discard a soft cheese that shows any sign of contamination.

You can usually save part of a hard cheese if the mold covers just a small surface area and there is no evidence of hyphae penetration. Cut away the afflicted area to a distance of 1 inch in all directions (including down) from the mold. Do not let the knife blade touch the tainted area.