Moldy Cheese: “Grate” or Gross?

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National Moldy Cheese Day is celebrated each year on October 9th, a day for all cheese lovers to come together and celebrate delicious moldy cheeses such as Brie, blue, Roquefort, and Camembert. These cheeses are delicious, but what about the moldy American slices in the back of my fridge? So why are some types of mold okay, but others aren’t? Today, I’m coming to the rescue of cheese lovers everywhere to answer this question and a few more of the most common questions surrounding moldy cheese and its food safety guidelines.

Why Is There Mold in Some Cheeses Anyway?

The simple answer is … some types of mold taste good! Most cheeses are made by adding bacteria, but only a select few have mold added to them. There are different strains of mold used in different types of cheeses, and each has a different effect on the taste of the cheese. For blue cheese, molds called Penicillium glaucom or P. roqueforti help to give blue cheese its bold, tangy flavor. Without mold, you would be left with a block of plain, salty fermented milk and a plate full of Buffalo wings begging for a punchier dip. Molds, like P. candidum, are used in Brie cheese and help form an earthy-tasting rind around the cheese, as well as helping a wheel of Brie go from a crumbly, dry cheese to a creamy and deliciously spreadable one.

Why Is Mold in Some Cheese Safe To Eat?

We’ve all had to throw out food that we didn’t eat in time and we’ve all been disgusted by the mold colonies that have formed on the forgotten foods in our fridge. But there’s a difference between mold injected into sophisticated, expensive, aged cheeses and the do-it-yourself mold on your old leftovers. The difference is a naturally occurring chemical called a mycotoxin. Mycotoxins are produced by certain molds and can cause gastrointestinal disturbance, immune suppression, kidney damage, and can even be carcinogenic. However, mold strains injected into cheeses do not produce mycotoxins, making them perfectly safe to sprinkle on your salad and spread on your baguettes.

How Do I Know If My Moldy Cheese Is Safe To Eat?

The first step to determining whether your moldy cheese is safe is knowing what cheeses intentionally have mold on them, and eating only molds that are already present in those cheeses when you buy them. For example, it is safe to eat the moldy rind of a Camembert wheel, but you should not eat leftover Camembert that has grown gray, fuzzy mold on the surface. However, if an unusual mold grows on a block of cheddar, it does not necessarily mean you need to toss it. On blocks of hard cheese such as Parmesan, Gouda, or cheddar, mold is unable to penetrate the surface of the cheese, and it can be made safe to eat by cutting off a 1 inch section of cheese around the mold spot. When rescuing your cheese from unwanted mold, be sure that the knife you use to cut the cheese does not touch the mold to avoid cross-contamination of the rest of the cheese.

Bonus Fact: Moldy or not, soft cheeses are not safe for pregnant women. The CDC recommends avoiding soft cheeses such as Queso Fresco, feta, Brie, and blue-veined cheeses while pregnant because these cheeses are often made without pasteurization. Pasteurization is a process used to heat milk and kills bacteria like Listeria monocytogenes, which can be particularly dangerous for pregnant women.

In short, mold in cheese can be safe and absolutely delicious. But let your cheesemonger do the molding, while you do the eating.