Cheese is a delicious, popular dairy product. Yet, if you’ve ever noticed fuzzy spots on your cheese, you may wonder whether it’s still safe to eat.
Mold can grow in all types of food, and cheese is no exception.
When mold appears on food, it typically means that you should throw it out. However, that may not always be the case with cheese.
This article explains whether moldy cheese is safe to eat — and how to distinguish the good from the bad.
Molds are a type of fungus that produces spores. They’re transported through air, insects, and water and can be found everywhere in the environment, including your refrigerator — though they grow best in warm, moist conditions (1).
Mold is a sign of spoilage in most foods. It tends to be fuzzy and green, white, black, blue, or grey.
When it starts growing, it’s usually visible on the food’s surface — though its roots can penetrate deeply. It changes the food’s appearance and smell, producing a sour or “off” odor (1).
Although molds are generally dangerous to eat, some types are used in cheesemaking to develop flavor and texture. These kinds are perfectly safe to consume.
Mold is a fungus that’s characterized by fuzzy, off-color spores. Though it’s normally a sign of spoilage when it grows on food, some types are used to produce certain cheeses.
Cheese is made by curdling dairy milk using an enzyme known as rennet, then draining off the liquid. The curds that are left behind are salted and aged.
Differences in cheeses’ taste, texture, and appearance depend on the type of milk, bacteria present, length of aging, and processing methods. In fact, particular kinds of cheese require mold during their production.
The most common types of mold used to grow cheese are Penicillium (P.) roqueforti, P. glaucum, and P. candidum. These molds help develop unique flavors and textures by eating the proteins and sugars in the milk, resulting in chemical changes (1, 2,
For instance, mold is what creates the distinct bluish veins in blue cheese. It’s also what gives Brie its thick outer rind and soft, creamy interior (2).
Mold-grown cheeses include (1, 2):
- Blue cheeses: Roquefort, Gorgonzola, Stilton, and other blue varieties
- Soft-ripened cheeses: Brie, Camembert, Humboldt Fog, and St. André
While soft-ripened cheeses are made by mixing mold into the milk during processing, blue cheeses generally have spores injected into the curds themselves (1).
Particular cheeses require molds to mature and develop their unique flavors. These include blue cheeses like Gorgonzola, as well as soft-ripened kinds like Brie.
Mold on cheese isn’t always an indicator of spoilage.
The molds used to produce certain varieties are different than the ones that sprout on your old cheese and bread.
Those used to manufacture cheese are safe to eat. They’re characterized by blue veins inside the cheese or a thick, white rind on the outside — whereas typical mold is a fuzzy growth that varies in color from white to green (1).
Besides appearance, odor can also indicate mold. Yet, because some cheese is naturally stinky, it’s best to smell it after purchasing to establish a baseline. This way, you can evaluate its freshness moving forward.
Keep in mind that dangerous spores can also occur on mold-grown cheeses. They’re similar in appearance to those that grow on other foods.
When to throw out moldy cheese
If you spot mold on your cheese, you don’t necessarily have to throw it out.
It’s rare for spores to spread far beyond the surface of hard cheeses, such as Parmesan, Colby, Swiss, and Cheddar. This means that the rest of the product is likely safe to eat. To salvage it, trim at least 1 inch (2.5 cm) around and below the mold (1, 4).
However, this technique doesn’t apply to soft cheeses or shredded, crumbled, or sliced varieties.
Any signs of mold on these kinds, which include cream cheese, cottage cheese, and ricotta, mean that it should be thrown out at once — as the spores can easily contaminate the entire product (4).
While mold is used to produce blue and soft-ripened cheeses, it’s a sign of spoilage on other varieties. Soft cheeses should be thrown out if spores appear, while hard ones can be salvaged by cutting around the molded area.
Molds can carry harmful bacteria, including E. coli, Listeria, Salmonella, and Brucella, all of which can cause food poisoning (
The symptoms of food poisoning include vomiting, stomach pain, and diarrhea. In severe cases, it may lead to death.
Dangerous molds can also produce mycotoxins, the effects of which range from acute food poisoning to immune deficiency and even cancer. In particular, the carcinogen aflatoxin has been shown to increase your risk of liver cancer (1,
The best way to minimize your risk of mycotoxin exposure is to avoid eating moldy food and practice safe food storage (
Harmful mold can carry bacteria and mycotoxins that may cause food poisoning, immune deficiency, and even cancer.
Exercising proper storing techniques can help prevent cheese from spoiling.
When selecting regular cheese, make sure it doesn’t have any cracks or mold growth. The texture should be smooth without any hardened or yellowed spots (4).
When purchasing mold-grown cheeses, keep an eye out for any fuzzy, off-color spots. Treat the blue-veined areas as a baseline to evaluate whether any unusual colors or textures appear.
You should refrigerate your cheese at 34–38°F (1–3°C). Wrapping your cheese tightly in plastic wrap can also help prevent mold spores (4).
Mold growth can be prevented through proper cheese storage. Wrap it in plastic wrap and make sure your refrigerator temperature is 34–38°F (1–3°C).
Cheese is a unique food in that some types are made with mold — a fungus that’s normally best to avoid.
Still, it’s important to know which types to eat, as moldy cheese can still be dangerous.
Blue and soft-ripened cheeses are grown with specific molds and safe to eat. However, if mold appears on soft, shredded, sliced, or crumbled varieties, you should discard them immediately.
Meanwhile, hard cheeses like Parmesan, Swiss, and Cheddar can be salvaged by cutting away the molded area.
As mold can cause food poisoning and other adverse health effects, you should always exercise caution and inspect your cheese thoroughly prior to eating it.