You just bought a piece of Parmesan and aren’t sure if it will go in the fridge or back in the pantry with the Kraft can. Or you’re at a party with Parmesan on the cheese board and wondering how long it can safely sit out. Does Parmesan cheese need to be refrigerated?
Short answer: Block and pre-grated refrigerated Parmesan cheese should always be refrigerated. Shelf-stable green cans do not require refrigeration before opening, but refrigerating after opening greatly increases its best quality and most labels recommend it. Parmesan is one of the most shelf-stable cheeses you can buy, but that doesn’t mean it never needs a refrigerator.
For a complete overview of how the shelf life of dairy and perishable foods compare, visit our complete food storage guide.
key takeaways
- Block Parmesan: Always keep in the refrigerator. Open lasts for 4 to 6 weeks. Wrap in parchment, not plastic.
- Pre-Grated Refrigerated Parmesan: Always keep in the refrigerator. Best within 3 to 5 days after opening; Maximum 7 days.
- Green Can (Shelf-Stable): Pantry before opening. Refrigerate after opening for best quality; Once opened it takes 10 to 12 months.
- Parmesan can be refrigerated up to 2 hours before serving On a cheese board. Hard cheese tolerates room temperature better than soft dairy.
- Never keep it on the refrigerator door. Fluctuations in temperature accelerate the deterioration of even hard objects.
- Parmesan freezes exceptionally well. Ingredients grated from a block go straight from the freezer to the pan without thawing.
Three-Product Refrigeration Guide
Refrigeration rules for Parmesan depend entirely on what type of product you have. Adopting the right rules for the right product can prevent both unnecessary waste and food safety errors.
| Type | before opening | after opening | shelf life after opening |
|---|---|---|---|
| Block or Wedge Parmesan | always refrigerate | Refrigerate; wrap in parchment | 4 to 6 weeks |
| Pre-grated refrigerated (bag or tub) | always refrigerate | Refrigerate; seal tightly | 3 to 5 days best quality; maximum 7 days |
| shelf-stable green can | the pantry is fine | It is recommended to refrigerate | Refrigerated for 10 to 12 months |
based on usda foodkeeper Guidance for hard cheeses and manufacturer’s recommendations. Green color can keep life safe according to Stilltasty. Always check for signs of spoilage before using.
Why does block Parmesan tolerate room temperature better than most cheeses?
The Science Behind the Stability of Parmesan
Parmesan (Parmigiano-Reggiano and similar older varieties) has an extremely low moisture content, typically 30% water, with a high salt concentration. Both factors create an inhospitable environment for the bacteria that cause most dairy spoilage. This is why a piece of Parmesan can sit on a cheese board at a dinner party for up to 2 hours without becoming dangerous, and why cheese was historically stored and transported at room temperature before modern refrigeration.
However, low moisture content does not mean protection from spoilage. Mold spores are everywhere in the air and can reside on the surface of Parmesan if given enough time at room temperature. Oxidation gradually reduces the flavor. And in a hot kitchen, degradation that would take weeks in the fridge happens in a few days. Refrigeration for block Parmesan is not about safety in the short term. It’s about preserving the complex nutty, crystalline flavor you paid for.
fda The 2-hour room temperature rule applies to all dairy, including hard cheeses. For serving on a cheese board, this gives you plenty of time for a dinner party or gathering. After 2 hours, put the cheese back in the refrigerator.
The Green Can: A Pantry Staple With Its Own Rules
Shelf-stable green canes (Kraft Grated Parmesan, Borden and similar brands) are a very different product from fresh Parmesan. It is dehydrated, heavily processed, contains anti-caking agents and preservatives, and contains virtually no moisture. Unopened, it’s actually shelf-stable for up to a year at room temperature.
Once opened, most labels recommend refrigerating for best quality. The dehydrated nature of the product means it will not spoil quickly even at room temperature, but refrigeration keeps the flavor sharper for longer periods of time and prevents the product from absorbing ambient moisture that could cause lumpiness.
The question of whether to refrigerate opened green cans is primarily about quality, not safety. The extremely low moisture content and preservative content of the product means it can remain at room temperature without posing a food safety risk. Refrigerating maintains the best flavor during the 10 to 12 month open window.
Parmesan on a cheese board: how long can it stay out?
Block Parmesan on a Cheese Board One of the most forgiving cheeses in terms of room temperature tolerance. Here’s how to handle it right.
Indoor service at normal room temperature: Take the Parmesan out of the refrigerator 20 to 30 minutes before serving so it can come to temperature. The flavor of Parmesan opens up dramatically at room temperature compared to straight from the fridge. Return to the refrigerator after 2 hours. Rewrap it in fresh parchment paper instead of returning it to its original wrapping.
Outdoor Recreation Above 90°F: The FDA guideline has been shortened to 1 hour. Keep the Parmesan in the cooler until serving. Its lower moisture makes it more tolerable than softer cheeses, but the 1-hour limit is still a safe guideline in high heat.
Pre-grated or freshly grated Parmesan to prepare the dish: The small amount used to finish pasta or pizza spends so little time at room temperature that food safety is not a concern. The container goes back into the fridge immediately after use.
How to store Parmesan cheese correctly
Best Storage Practices
First, wrap the block Parmesan in parchment paper. Never wrap plastic directly on a surface. Plastic traps moisture and promotes mold on the surface. The parchment allows the cheese to breathe. Wrap in parchment, then squeeze out air and place in a loose zip-top bag.
Store in the cheese drawer or at the back of the main shelf. Constant cool and light humidity are ideal. The door is the worst place for anything.
Keep the green container tightly closed between uses. Moisture is the enemy of dehydrated Parmesan in shelf-stable cans. Whether refrigerated or not, firmly replace lid immediately after each use.
See also
Do not grate more than necessary at one time. Freshly grated Parmesan from a block is best used within 1 to 2 weeks. Grating on demand preserves the shelf life of the blocks and improves the fresh taste.
Freeze the extra before it runs out. Grate and freeze the Parmesan before the 6-week open block window closes. Frozen grated Parmesan goes straight from the freezer to the pan and doesn’t need to be thawed.
Save the peel. Wrap Parmesan rinds and place in a sealed bag in the freezer. Add to soups, stews and risotto for a deep flavorful richness that replaces long-boiled dishes.
Use clean, dry utensils at all times. Wet pots introduce moisture into both the block and the can, promoting mold and clumping, respectively.
Recipes that use Parmesan cheese
Frequently Asked Questions
Is it necessary to refrigerate a Kraft Green can after opening?
Most labels recommend refrigerating after opening for best quality, and this is a good practice. The product is shelf-stable before opening due to its extremely low moisture content and preservatives, but storing in the refrigerator after opening maintains the most intense flavor during a long unopened shelf life of 10 to 12 months. Some people keep the can in the pantry after opening without any problems – the product is dry enough that it is not a significant food safety concern. If you use it within a few months, pantry storage is fine. If you plan to keep it for about a year after opening, the refrigerator is a better option.
I left a piece of Parmesan on the counter overnight. Is it still safe?
Especially for block Parmesan, overnight is more favorable than overnight with soft dairy, but it’s still more than the FDA’s 2-hour safe guideline. Examine the cheese carefully: check for any mold growth, smell it for any rancid or sour notes, and check the texture. If it looks and smells completely normal, it is safe to use in a baked application where it will be heated. Don’t serve it on a cheese board or grate it on any dish without cooking it. If pre-grated Parmesan has been left out overnight, remove it.
Can I freeze Parmesan cheese?
Yes, and Parmesan is one of the best things to freeze. Its extremely low moisture content means that the ice crystals cause minimal damage to the texture during freezing. A block of Parmesan keeps for 12 to 18 months. Grated Parmesan keeps frozen for up to 6 months. Best practice: Grate the blocks and store in a zip-top bag before freezing. Frozen grated Parmesan goes straight from the freezer into hot pasta sauce, risotto or soup without thawing. It really is one of the most practical freezer items available.
Further reading
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