Does Parmesan Cheese Go Bad?

So you’ve bought a big block of parmesan on a sale to use as a topping for your casseroles. And as the cheese sits in the fridge, after a few weeks, you start wondering: does parmesan cheese go bad?

Or maybe you’ve chosen the more convenient approach and went with shredded or grated parmesan that you can use right away. And now you’re not quite sure how long will the opened parmesan last or if you should refrigerate it or not.

Either way, if you’d like to learn a few things about storage, shelf life, and going bad of parmesan, this article is for you. In it, we cover both chunks of parmesan as well as its grated and shredded variation.

If that’s something you’d like to learn more about, read on.

How To Store Parmesan Cheese

Let’s start with storing a block (or a chunk) of parmesan. It’s not much different than storing any other hard cheese.

When it comes to where to keep it, you should place it in the fridge once you get home, possibly into the vegetable crisper that’s usually fairly humid. The blocks are usually vacuum-sealed, and there’s no point in opening the package before you need the cheese.

Once you open the package, there are a few options when it comes to storage. Wrapping the package (or only the cheese) in aluminum foil is one. Alternatively, you can wrap the cheese with cheese paper, wax paper, or parchment paper.

Fortunately for us, someone run a test of various storage methods, to tell us what’s the best option. Based on this article from Cook’s Illustrated simply putting the cheese in a freezer bag and sealing it tightly gives great results. Oh, and remember to squeeze as much air from the bag as you can before fastening the seal.

Cheese-topped pizza pie
(credit: Jamie Goodwin)

When it comes to shredded and grated parmesan, there are a lot of products out there. And not all of them are created equal.

Basically, you can find both refrigerated and unrefrigerated versions of these. So the best place to store an unopened package is to store it the same way it was stored in the supermarket.

Once you open it, no matter which variety we’re talking about, its place is in the fridge and tightly sealed. And remember always to use clean utensils when scooping the cheese, to prevent any microbial contamination.

Parmesan Reggiano cheese
Image used under Creative Commons from Robin Ellis

Can You Freeze Parmesan?

If you want to store a block of parmesan for a prolonged period, you can freeze it. No additional prep required, just make sure the cheese is well wrapped (e.g., in a freezer bag) before you put it into the freezer.

Thaw the cheese in the fridge overnight. Please note that if you plan on using the cheese grated or shredded, it’s better to prepare it before freezing. After thawing it might not be that easy to grate/shred it.

You can freeze shredded or grated parmesan as well. Again, make sure the cheese is well protected from cold air before you chuck it into the freezer.

Warning

Please note that the frozen cheese might get sticky. Because of that, it probably won’t be that easy to grab just a few spoonfuls for a casserole topping.

To work around that, consider portioning the cheese into a few freezer bags. This way you can easily grab only a small amount. Thaw in the fridge or transfer directly onto the dish you’re cooking.

Cooked pasta topped with parmesan
(credit: Filip Mishevski)

How Long Does Parmesan Cheese Last

Parmesan is a hard cheese, and as such a product it lasts quite some time.

Unopened, the parmesan should last about 7 to 9 months. Of course, the label should include a “use-by” or “best if used by” date, or something like that. And since parmesan is a long-lasting cheese, it should still be okay for a few weeks past that date.

Once you open the package, the parmesan should retain freshness for about 4 to maybe 6 weeks.

Spaghetti carbonara
(credit: Bruna Branco)

When it comes to shredded or grated parmesan that’s sold refrigerated, it should have a “use-by” date too. Since the product is shredded, its quality degrades faster. Thus it should keep for about a week past that date, and that’s it.

Once you open the package, use the cheese within 3 to 5 days for best quality, and maybe up to 7 days for an okay quality.

Last but not least, there’s also the grated parmesan that comes in unrefrigerated canisters. It usually lasts about a year, or even more. That parmesan always comes with a best-by date, and you can easily assume that it will keep at least a month past that date. The cheese is dehydrated, so it’s not prone to bacteria growth, hence the long shelf life.

Once you open the package, keep the canister in the fridge. It should last at least a couple of months, but check the label to make sure.

 PantryFridge
Parmesan (unopened) 7 – 9 months or Use-by + 1 month
Parmesan (opened) 4 – 6 weeks
Shredded/grated parmesan (sold refrigerated, unopened) Use-by + 7 days
Shredded/grated parmesan (sold refrigerated, opened) 3 – 7 days
Grated parmesan (sold unrefrigerated, unopened)Best-by + 1 month 
Grated parmesan (sold unrefrigerated, opened) 4 – 6 months

Please note the periods above are estimates only.

How To Tell If Parmesan Cheese Has Gone Bad

Usually, when cheese goes bad, it is easy to see the mold spots. With hard cheeses like Parmesan, the mold spots can be removed, and you can eat the rest. But what if the cheese is grated or shredded?

When grated, Parmesan is white to beige in color. If you are wondering if your grated cheese has spoiled, open the container and check the color and smell. Parmesan going bad will smell funny, and the color will look different. Instead of looking white or beige, the color of the cheese will be more of a yellow or darker beige.

For shredded parmesan, texture change is a good sign of it going bad. If the shredded parmesan feels spongy or wet to the touch, discard it. Same thing if it smells off or “funny.”

For both grated and shredded parmesan, throw the whole package out if there are any signs of mold.