All About Aged parmesan
Your complete guide to aged parmesan - discover how to store it properly, identify when it's gone bad, and find the best substitutes for your recipes.
How Long Does Aged parmesan Last?
Storage times and freshness tips for aged 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.
Unopened Block in Fridge6-12 months
Signs of Spoilage
Pungent, sour, or ammonia-like smell (beyond its natural aroma), visible mold (uncommon if sealed properly), sliminess, or excessive hardening/drying out indicating moisture loss.
How to Check
Visually inspect the packaging for any signs of damage or bulging. Smell the cheese through the packaging if possible for any strong off-odors. The cheese should appear firm and consistent in color.
Storage Tips
Aged parmesan is a hard cheese with low moisture, making it less susceptible to rapid spoilage. Often, it can last well past its 'best by' date if kept sealed and refrigerated. Keep it in the coldest part of your fridge.
Grated/Shredded in Fridge1-2 weeks
Signs of Spoilage
Visible mold, strong sour or ammonia-like smell, clumping (if it was originally loose), significant change in color (darker yellow/orange), or a noticeably drier, harder texture.
How to Check
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Visual Inspection: Look for any fuzzy mold spots or discoloration.
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Smell Test: A strong sour or off-putting ammonia scent is a clear indicator of spoilage.
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Texture Test: It should have a consistent texture; excessive clumping or an unusually dry, hard feel can indicate it's past its prime.
Storage Tips
The increased surface area of grated or shredded cheese makes it more prone to spoilage. Store in an airtight container or a sealed bag to minimize air exposure and prevent moisture loss. Always use clean utensils when scooping.
Frozen (Block or Grated)6-12 months
Signs of Spoilage
While mold won't grow in the freezer, signs of spoilage after thawing include a significantly altered, mealy, or crumbly texture (beyond the expected change from freezing), freezer burn (dry, discolored patches), or an off-flavor/smell that wasn't present before freezing.
How to Check
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Visual Inspection (after thawing): Check for excessive freezer burn or any signs of mold that might have been present before freezing.
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Texture Test (after thawing): The cheese will likely be more crumbly or mealy; however, it should not be slimy or mushy.
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Smell/Taste Test (after thawing): It should still have a recognizable parmesan aroma, though possibly less intense. Any sour or off-flavors indicate spoilage.
Storage Tips
To freeze a block: Wrap tightly in plastic wrap, then foil, and place in a freezer-safe bag. For grated cheese: Place in a freezer-safe bag or container, removing as much air as possible. Thaw in the refrigerator. Frozen and thawed parmesan is best used for cooking, grating over hot dishes, or in sauces, as its texture may become more crumbly and less ideal for eating plain.
Opened Block in Fridge3-4 weeks
Signs of Spoilage
Visible mold (blue, green, black, or white fuzzy spots) beyond minor surface spots, strong unpleasant ammonia or sour smell, slimy or unusually soft texture, significant discoloration (darker yellow/orange in areas).
How to Check
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Visual Inspection: Look carefully for any mold growth, especially on cut surfaces or edges.
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Smell Test: Inhale deeply; it should have a pleasant nutty, salty, umami aroma. A sour, pungent, or ammonia-like smell indicates spoilage.
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Touch Test: It should feel firm and dry, not slimy or unusually soft. If mold is present on a hard cheese, you can often cut off at least 1 inch (2.5 cm) around and below the moldy spot; however, discard if the mold is extensive, covers a large area, or penetrates deeply.
Storage Tips
To extend freshness, wrap the cheese first in parchment paper or cheese paper (which allows it to breathe), then tightly in plastic wrap, foil, or place in an airtight container. This prevents it from drying out while minimizing moisture buildup that can promote mold. Avoid wrapping directly in plastic wrap for extended periods, as it can trap moisture.