Before pasteurization became the norm in the food industry, the liquid that was remaining after butter was churned was nothing but good old buttermilk. The cream used to be set aside for maturing before the churning process and this caused proliferation of bacteria that converted the sugars present in the milk to lactic acid. Hence, the slightly sour yet buttery flavor of buttermilk. Today, buttermilk is cultured by introducing lactic acid bacteria in pasteurized milk.

Measuring cup with buttermilkImage used under Creative Commons from jeffreyw

Here are some facts about storing buttermilk and knowing when to chuck it out.

Buttermilk Storage

Buttermilk is a dairy product. So, just like any other dairy product it has to be refrigerated. Whether the carton of buttermilk is opened or not, don’t forget to keep it in your fridge.

However, if you want to prolong the shelf life of buttermilk, the best way to store it is by freezing it. Pour the buttermilk into an airtight container and then place the container in your freezer. This should allow you to store the unused buttermilk for about 2 months without worrying.

In case you use buttermilk regularly for cooking and baking, freeze it in portion-size containers. This will allow you to thaw the buttermilk as and when you require it. Just remember, once you freeze and thaw buttermilk, there will be a difference in its consistency and taste. Hence, use this method of storage only if you use the product for cooking purposes.

Buttermilk Shelf Life

The shelf life of buttermilk is dependent on a few factors, such as the method of processing the buttermilk, the sell-by date printed on the carton, how was the buttermilk stored and whether it was exposed to heat and light.

Opened Buttermilk: The shelf life of opened buttermilk when refrigerated is about 14 days. However, even after the expiration date the buttermilk is still good to go for another 7 days. You will not notice a difference in its taste, flavor and texture.

Unopened Buttermilk: On the other hand, if the buttermilk is refrigerated unopened, you can rest assured it will be alright for about a month. Sometimes, it can be good for use even after a month.

Just remember if you want to drink it, do so within two weeks of the manufactured date printed on the carton. Thereafter, use the buttermilk just for cooking.

If you are freezing buttermilk, make sure you use it within 3 months of freezing it. That is when you can be certain of the quality and flavor.

Jar with buttermilkImage used under Creative Commons from Rebecca Siegel

Has Your Buttermilk Gone Bad?

Due to the consistency and texture of buttermilk, many people find it difficult to identify when it has gone bad. However, here are some ways to identify spoiled buttermilk:

  • Greenish or dark mold formation on the surface of the buttermilk. You can also check the edges of the carton. If you notice mold on the edges, discard the buttermilk immediately.
  • Stir the buttermilk with a spoon and then check its consistency. If the consistency seems off or unlike what buttermilk should have, it is spoiled and shouldn’t be used.
  • Buttermilk has a naturally sour odor. However, when it gets spoiled, this odor becomes excessively strong. At times, it will smell like curdled milk. If you notice this, throw it away.
  • Lastly, though not advisable, you can taste the buttermilk. If the taste seems off or very sour, its gone bad and shouldn’t be used. Just remember you are risking diarrhea by tasting spoiled buttermilk!

The Bottom Line
Today, pasteurized milk is spoiled on purpose to create buttermilk. However, even this “spoiled” product can go bad. Under normal circumstances, you can keep opened buttermilk for about 2 weeks or 14 days and unopened for about a month. Buttermilk has a limited shelf life, but you can extend it to about 2 to 3 months by freezing it.