Once opened, Kefir (fermented milk) keeps about 1–2 days in the fridge. Unopened, it keeps about 1 week.
1–2 days opened in the fridge, against 1 week sealed in the fridge. Green is what this situation leaves you; husk is what it spends.
| Situation | Keeps for |
|---|---|
| Unopened · fridge | 1 week |
| Opened · fridge | 1–2 days |
| Freezer | Not recommended |
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 1–2 days refrigerated at 40°F (4°C) or below, according to USDA FoodKeeper v128. Refrigerate it once it's open.
Yes — keep Kefir (fermented milk) at 40°F (4°C) or below once it's open. Refrigerate at 40°F (4°C) or below.
Look for: Sour or off smell; Mould or fuzzy spots; Curdled, slimy, lumpy, or separated texture; Yellowing or other discoloration. Those are the general signs for dairy & eggs — USDA FoodKeeper v128 publishes no spoilage note for Kefir (fermented milk) specifically. Never taste something to test it — when in doubt, throw it out.
USDA FoodKeeper v128 does not recommend freezing Kefir (fermented milk) — it survives but the texture or quality suffers badly.