Moldy Cheese Day

What the day is

Moldy Cheese Day is observed on October 9. It is a quirky, unofficial food day with no recorded founder, and it works as an excuse to talk about something cheese lovers already know: some of the best cheeses in the world are made with mold on purpose.

The distinction matters, because the day is not a dare to eat the forgotten block at the back of the refrigerator. Cheese mold falls into two very different groups, the kind cheesemakers cultivate and the kind that simply grows where it should not.

Origin and background

Blue cheeses get their veins from molds in the Penicillium family, most often Penicillium roqueforti. The cheese is pierced with needles so air can reach the interior, and the mold grows along those channels. Roquefort, one of the oldest blue cheeses, is traditionally ripened in the natural limestone caves at Roquefort-sur-Soulzon in southern France. Brie and camembert are different: their white, bloomy rind is Penicillium camemberti, which also softens the cheese from the outside in.

Unwanted mold is another matter. The United States Department of Agriculture advises that on hard cheeses such as cheddar or parmesan you can cut away at least an inch around and below the moldy spot and keep the rest. Soft cheeses, shredded cheese, sliced cheese and cream cheese should be thrown out, because mold can spread invisibly through them. Cheese that was never meant to be moldy but is fuzzy with blue or green growth is a candidate for the trash.

How to take part

• Build a board with a blue cheese, a bloomy-rind cheese and a hard aged cheese, and compare them side by side.
• Pair blue cheese with something sweet, such as honey, pears or walnuts, which balances the sharpness.
• Check the refrigerator for the accidental kind, and use the one-inch rule only on hard cheese.
• Visit a cheese counter and ask for a taste of something you have not tried.
• Cook with blue cheese in a salad dressing, on a burger or melted into a sauce.