Prosciutto

Dry-cured hams behave unlike anything else in this category, and the storage advice depends heavily on how dry the product actually is.

Genuinely dry-cured, tightly wrapped prosciutto keeps a long time refrigerated — around 2–3 months, or the package date if it is shorter. Wrap the cut face directly against the meat in plastic or butcher paper. Air is the enemy: exposed slices oxidize and harden within a day.

Deli-sliced product sold moist is a different thing despite the same name, and should be treated as ordinary deli meat at 3–5 days. If you are unsure which you have, use the shorter window.

Freezing is possible for 1–2 months but is not recommended — the texture that justifies the price does not survive ice crystals.

Whole uncut legs are traditionally kept at cool room temperature, but that relies on a low-humidity environment and an intact rind; in an ordinary kitchen, refrigerate.

Prosciutto is preserved by dehydration and salt, not by refrigeration, which is a fundamentally different mechanism from everything else on this site. Months of salting and air-drying reduce the water activity to a level at which bacteria simply cannot grow. This is the oldest form of meat preservation there is, and it is why a whole leg can hang at room temperature for a year.

The consequence is that refrigeration is a quality measure as much as a safety one, and that the usual timelines do not transfer. It also means that once the product is sliced thin and exposed to humid refrigerator air, it starts moving back toward ordinary meat behavior.

White crystalline specks on the surface are usually tyrosine, an amino acid that precipitates out during long curing. They are a marker of proper aging, not mold, and they are harmless — they crunch slightly and taste faintly savoury.

What is not normal: a slimy or wet surface, a sour smell as opposed to the deep nutty funk of correct curing, and fuzzy colored mold on a cut face. Discard on any of those.