Once opened, Marshmallows keep about 1 month in the pantry. Unopened, they keep about 1 year.
1 month opened in the pantry, against 1 year sealed in the pantry. Green is what this situation leaves you; husk is what it spends.
| Situation | Keeps for |
|---|---|
| Unopened · pantry | 1 year |
| Opened · pantry | 1 month |
Air and warmth are what shorten an opened item's life — the right container buys back the days the packaging gives up once the seal's broken.
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About 1 month in the pantry, according to USDA FoodKeeper v128.
Marshmallows are shelf-stable at room temperature: cool, dry pantry, sealed — refrigerating after opening is optional and mainly preserves quality. Refrigerating it mainly preserves quality rather than safety.
Look for: A rancid, paint-like, or musty smell; Bulging, leaking, deeply dented, or rusted cans; Insects or webbing in dry goods; Mould or discoloration. Those are the general signs for pantry staples — USDA FoodKeeper v128 publishes no spoilage note for Marshmallows specifically. Never taste something to test it — when in doubt, throw it out.