How can you tell if Parmesan (block) has gone bad?

Signs that Parmesan (block) has gone bad: Whiskered fuzzy mold, soft or slimy patches, ammonia smell; White surface crystals are flavor crystals — not mold.

What does the date label on Parmesan (block) mean?

Parmesan (block) usually carries a "Use By" date. The last date the manufacturer recommends for peak quality — for most foods this is still quality-based, not a safety cutoff (infant formula is the one exception). See our date-labels guide for the full breakdown.

Dairy

How long does Parmesan (block) last?

Q: How long does Parmesan (block) last?

In the fridge: 2 months. In the freezer: 1 year. Sealed / unopened: Same. Wrap tightly in plastic wrap or wax paper. Harder cheeses keep longer.

High confidence Safety concern

How long does Parmesan (block) last? fridge 2 months, freezer 1 year. Plus spoilage signs, sources, and an unopened-vs-opened note.

Fridge

2 months

Pantry

Refrigerate only

Freezer

1 year

Sealed / unopened: Same

Signs Parmesan (block) has gone bad

Whiskered fuzzy mold, soft or slimy patches, ammonia smell.
White surface crystals are flavor crystals — not mold.

Discard immediately if

Mold on soft cheese (brie, cream cheese, ricotta) — discard the whole block
Sour or rancid smell
Texture is unusually dry, cracked, or slimy

Why guidance varies

Dairy spoilage depends on initial pasteurization, fridge temperature, and how often the container is opened; manufacturer-printed dates assume continuous storage at 40°F (4°C) or below.

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Sources for this answer

A USDA FoodKeeper — Storage windows and refrigeration guidance for this category.
A USDA FSIS — Food Product Dating — Date-label interpretation and food-safety baseline.

Reviewed: 2026-05 · Rule: if manufacturer storage instructions are stricter than category guidance, the manufacturer instructions win.