How long does buttermilk last?

Buttermilk keeps 1 to 2 weeks in the fridge from the day you buy it, and about 3 months in the freezer.

Food	Fridge	Freezer
Buttermilk	1–2 weeksfrom purchase	3 monthsfrom purchase

Fridge at 4 °C (40 °F) or colder, freezer at −18 °C (0 °F). Freezer times are for best quality: food kept frozen stays safe, but slowly loses taste and texture. These times are USDA guidance, not a guarantee. When in doubt, throw it out.

How to tell if buttermilk has gone bad

Buttermilk is naturally tangy and thick, so look for changes: a much stronger, rancid smell.
Chunks that don't stir back in, or a very thick, almost solid texture.
Mold, or a pink, gray or green color.

How to store buttermilk

Keep buttermilk on a shelf at the back of the fridge, tightly closed.
Shake it before use: it separates naturally.
Most recipes need only a cup, so freeze the rest in measured portions.

Can you freeze buttermilk?

Yes, for about 3 months. Freeze it in measured portions, or in ice cube trays, leaving room for it to expand. Thawed buttermilk separates and is thinner, so shake it well and use it in baking, pancakes and marinades rather than drinking it.

Questions

How can you tell if buttermilk is bad when it's already sour?

Fresh buttermilk smells tangy, like yogurt. Spoiled buttermilk smells sharply rancid, grows mold or turns lumpy and discolored.

Can you use buttermilk after the date?

Buttermilk kept cold often stays good a little past its date for baking, if it smells normal and shows no mold.

What can replace buttermilk?

Stir 1 tablespoon of lemon juice or white vinegar into 1 cup (240 ml) of milk and let it stand for 5 to 10 minutes.

Add buttermilk to ShelfLife, and get a reminder to use or freeze the rest of the carton.

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