When Does Cheese Spoil?
Although mold is usually a warning sign that food needs to be thrown away, this isn't always the case with cheese. Some cheeses, such as blue cheeses, use molds as part of their manufacturing process and the molds add layers of flavor essential to a cheese's character.
Pay closer attention to expiration dates and mold on soft cheeses because they spoil more quickly.
How Long Cheeses Stay Fresh
Standard American cheese slices should last about six months in the refrigerator. For block cheeses, the softer the cheese, the shorter its life. Fresh mozzarella generally will last a week to 10 days before it starts to spoil. Use cream cheese up to two weeks after its "best before" date. The freshness of cottage or ricotta cheese also can be based on the expiration date, but use it within a week. You have about two weeks from the day you open it to use soy cheese. Soft cheeses, such as brie and Camembert will keep for around 10 days. Harder cheeses made from cow's or goat's milk will keep for about six months unopened or about a month if they've been exposed to the air.
To keep cheese fresher longer or at least to its standard "shelf life," you can wrap it tightly in plastic and store it in the cheese tray of your refrigerator. It's best to try to get as much air as possible out of the packaging after opening and refrigerating. For cheeses that come in a liquid, such as mozzarella, change the water every couple of days.
You don't need to get rid of a hard cheese if it has been left out of the refrigerator. Many fine cheeses should be brought to room temperature before you serve them to bring out their full flavor. The exception is soft cheeses, which should stay refrigerated. If soft cheeses have been out for more than four hours, throw them out.
What to Do if You See Mold
Mold on a brick of cheese doesn't necessarily mean you need to throw it out. Because cheese is created under a controlled molding process, you can slice a 1-inch around the area where the mold has formed and it will be edible. This does not apply to cream cheese, cottage cheese, ricotta cheese or mozzarella. If those types of cheese have visible mold or smell moldy, throw them away. Vegan cheese is made from a different process, so when it's moldy, it should be thrown out.
If the cheese smells bad, throw it out and do not taste it. Trust your senses. Cheeses made with mold, including unpasteurized Camembert, blue cheese, brie, feta and Mexican soft cheeses may carry the risk of Listeria monocytogenes. If you are pregnant or have a weakened immune system, talk to your doctor before you eat these types of cheeses.