All About Parmesan
Your complete guide to parmesan - discover how to store it properly, identify when it's gone bad, and find the best substitutes for your recipes.
How Long Does Parmesan Last?
Storage times and freshness tips for parmesan in different conditions.
Safety first: This guide provides general information. When in doubt, throw it out! Trust your senses and err on the side of caution. If something smells, looks, or tastes off, don't consume it.
frozen grated3-4 months
Signs of Spoilage
Freezer burn (dry, discolored clumps) affecting texture and flavor. No typical spoilage signs like mold once frozen.
How to Check
Visual inspection: Check for freezer burn. The cheese might be slightly drier.
Storage Tips
Store in an airtight freezer-safe bag or container. Can be used directly from frozen in cooking or as a topping without thawing.
shelf-stable grated (unopened, pantry)Until 'best by' date (typically 6-12 months)
Signs of Spoilage
Extreme clumping that won't break apart, strong rancid or chemical smell, significant discoloration, or very rarely, mold if moisture has somehow entered.
How to Check
Visual inspection: Check for hard, solid clumping or unusual colors. Smell test: Should have a mild, cheesy aroma. A rancid, sour, or chemical smell indicates spoilage.
Storage Tips
Store in a cool, dry place away from direct sunlight. This product is designed for pantry storage due to its processing and low moisture content.
shelf-stable grated (opened, pantry)1-3 months
Signs of Spoilage
Hard, solid clumping that cannot be broken up, rancid or chemical smell, mold (rare but possible if moisture is introduced).
How to Check
Visual inspection: Look for hard clumping or any visible mold. Smell test: A rancid, sour, or chemical smell indicates spoilage.
Storage Tips
Keep the lid tightly closed to prevent moisture and air exposure. While designed for pantry storage, some prefer to refrigerate it once opened, which can extend its freshness but may lead to more clumping due to condensation.
pre-grated/shredded (refrigerator, opened)1-2 weeks
Signs of Spoilage
Significant clumping, sour or ammonia-like smell, visible mold (often green or blue spots).
How to Check
Visual inspection: Look for mold, unusual discoloration, or very hard clumping. Smell test: Any off-smell (sour, ammonia, musty) indicates spoilage.
Storage Tips
Store in an airtight container or seal the original bag tightly, pressing out excess air. The large surface area and exposure to air accelerate spoilage.
unopened block/wedge (refrigerator)6-12 months (often good past 'best by' date)
Signs of Spoilage
Significant discoloration (beyond normal aging), widespread soft mold (unlikely if sealed), strong ammonia-like or putrid smell, excessive sliminess.
How to Check
Visual inspection: Check for any unusual growth or extreme discoloration. Smell test: A fresh, nutty, pungent aroma is normal; a strong ammonia or sour smell is a red flag.
Storage Tips
Parmesan, being a hard, aged cheese, has a very long shelf life. Keep it in its original vacuum-sealed packaging until ready to use. Store in the coldest part of your refrigerator.
opened block/wedge (refrigerator)3-6 weeks
Signs of Spoilage
Visible mold (white, green, black, pink, or fuzzy growth), slimy or greasy texture, strong sour or ammonia-like smell, very hard and dry to the point of being crumbly and unworkable.
How to Check
Visual inspection: Look closely for any fuzzy mold. For hard cheeses, small spots of surface mold can often be safely cut off (remove at least 1 inch around and below the mold). Touch test: It should feel firm, not sticky or slimy. Smell test: A pleasant, pungent, nutty aroma is good. A sour, ammonia, or 'off' smell means it's likely spoiled.
Storage Tips
Wrap tightly in parchment paper, then in plastic wrap or aluminum foil. This allows the cheese to breathe slightly while preventing it from drying out too quickly or absorbing fridge odors. Store in the cheese drawer or a less cold part of the refrigerator.
freshly grated (refrigerator)5-7 days
Signs of Spoilage
Clumping together, sour or ammonia-like smell, visible mold growth (even small spots), discoloration.
How to Check
Visual inspection: Check for clumping, any unusual colors, or mold. Smell test: Should smell fresh and nutty. An off, sour, or strong ammonia smell indicates spoilage.
Storage Tips
Store in an airtight container or a sealed bag. Due to the increased surface area, freshly grated Parmesan spoils much faster than a block. It's best to grate only what you need.
pre-grated/shredded (refrigerator, unopened)Until 'best by' date (typically 1-2 months)
Signs of Spoilage
Excessive moisture or significant clumping (beyond normal anti-caking agent effects), sour or ammonia smell, visible mold.
How to Check
Visual inspection: Check for mold or unusual clumping. Smell test: Should have a mild, cheesy aroma. Any sour or off-smell is a sign of spoilage.
Storage Tips
Always check the 'best by' date. Store in the refrigerator. The anti-caking agents used in some pre-grated cheeses help prevent clumping but do not stop spoilage.
frozen block/wedge3-6 months (quality might degrade after this, but remains safe)
Signs of Spoilage
Severe freezer burn (large dry, discolored patches) affecting texture and flavor, though it's still safe to eat. No typical spoilage signs like mold once frozen.
How to Check
Visual inspection: Check for excessive freezer burn. Texture might become more crumbly after thawing.
Storage Tips
Wrap the block or wedge tightly in plastic wrap, then aluminum foil, or place in a freezer-safe bag. Thaw in the refrigerator. Can be grated directly from frozen for convenience.