Moldie Oldies

• Many of the world's most revered cheeses are deliberately infected with mold spores, so it's clear that mold isn't necessarily a reason to discard your cheese. The problem is that not all molds are benign. Many have unpleasant flavors, and some provoke violent allergic reactions. Some molds also produce powerful and dangerous toxins, called mycotoxins, which can have serious health effects. Complicating the issue, the part of the mold you see isn't the whole organism. Mold sends root-like filaments, called hyphae, deep beneath the cheese's surface. Just scraping away the patches you see isn't enough to fix the problem.

That Important Inch

• The U.S. Department of Agriculture's food safety guidelines recommend cutting a full inch below the moldy spot, to remove not only the visible surface mold but the hyphae -- and any potential toxins -- beneath. With a very hard cheese such as Parmesan, or a moderately firm cheese such as cheddar, this is perfectly safe. The problem for Parmesan lovers is that costly Parmigiano-Reggiano and similar premium-priced cheeses often appear in slender wedges. It can be difficult to trim an inch from the sides of a wedge, but it's practical if your mold is only on the end of the cheese.

An Exception

• If you have a separate area in your refrigerator reserved especially for cheeses, you might not need to carve a costly gouge from your premium Parmesan. The fluffy white mold that gives Brie and Camembert their distinctive rinds will eagerly colonize Parmesan or any other cheese that's nearby. So will the blue or blue-green molds that give blue cheeses their flavor. These benign molds can simply be scraped away from the surface of your Parmesan. When it's cleaned, wipe the surface of the cheese with a few drops of vinegar on a clean cloth. Enclose the Parmesan in fresh wrappings, and return it to your fridge.

The Storage Issue

• Minimize the risk of your Parmesan getting moldy by following a few basic principles of cheese storage. If you ordinarily keep white-mold or blue-mold cheeses on hand, give them a storage area separate from non-moldy cheeses. Wash your Parmesan's storage area between uses with soapy water, then wipe it down with bleach or vinegar to kill any mold spores. The cheese itself is best when wrapped in cheese paper, or parchment paper if that's not available. Enclose the paper-wrapped cheese in a loose plastic bag to keep out any stray odors from your refrigerator.