Does Buttermilk Go Bad? How Long Does Buttermilk Last?

Buttermilk is commonly used in cooking recipes like pancakes, biscuits, or soda bread.  It’s a milk product, so it’s usually kept in the fridge.  But how long can it last?

Quick Answer

Buttermilk comes in a liquid or a dried powder.  An unopened container of liquid buttermilk can last a week or two at most past its “best by” date.  Once opened, the buttermilk can survive for one to two weeks.  Opened or not, buttermilk lasts up to up to three months in the freezer.  Dried buttermilk lasts three to five years unopened under ideal storage conditions, and six months to a year once it’s been opened.


Here is a quick guide to how long your buttermilk will stay good, and how to know when it’s going bad.

Does Buttermilk Go Bad? How Long Does Buttermilk Last?

Buttermilk contains lactic acid that prevents bad bacteria from forming, similar to yogurt.  In fact, there are two kinds of buttermilk: cultured buttermilk that you can find in a store, and traditional buttermilk, which is what powdered buttermilk is made from.  Most people use cultured buttermilk.

How Long Does Buttermilk Last Outside?

Since buttermilk is a milk product, it can’t stay outside of a refrigerator for very long.  The normally recommended time to leave a cold dairy product like milk out of the fridge is two hours, buttermilk probably lasts a bit longer due to its acidity, but it should be checked for any signs of going bad.

Powdered buttermilk doesn’t have to be stored in a fridge, since it’s evaporated.  It can last three to five years if kept in the original unopened container in a cool, dry place.

Once the original container has been opened, it lasts six months to a year.  Keeping the milk in an air-tight container with an oxygen absorber is the best way to make it last.

How Long Does Buttermilk Last in the Fridge?

Store-bought Buttermilk can last up to two weeks past its “best-by” day if kept in the refrigerator.  That, however, is the maximum.  It’s more likely to last one week.

Homemade buttermilk doesn’t last as long since it hasn’t been put through the same sterilization processes.  Your homemade milk will last two to three days if kept in an air-tight container.

When you store it in the fridge, place the container as far back as you can.  Buttermilk does better in a constant temperature.  Make sure you open the container as little as possible, to reduce any exposure to warmth or light.

How Long Does Buttermilk Last in the Freezer?

If you really want your buttermilk to last, then the freezer is your best bet.  It can last up to three months in the freezer if stored in an air-tight container.  Don’t forget to put a label on the container, so you know how long it’s been there.

Buttermilk, like most dairy products, changes its texture when it’s frozen.  This is because the ingredients tend to separate.  It’s still safe to eat and especially to use in baking, and you can recombine the ingredients by mixing them together, but directly drinking it won’t be quite the same.

When you freeze your milk, don’t forget to leave a bit of room for expansion.  Milk products expand when frozen, and need some room to grow.

As with any dairy product, the amount of time buttermilk can last is only an estimate.  Maybe it will last longer, or not as long.  The only way to find out is to check for signs of it going bad.

How To Tell If Buttermilk Has Gone Bad?

Here are some signs that your buttermilk is going bad.  Remember that if you have any doubts about if your buttermilk then it’s probably a good idea to throw it out.

It smells funny: If your buttermilk smells a bit off, it’s time to throw it out.  The proteins inside the milk have started to break down and curdle.

Thickness or Lumpiness: While small lumps are common in buttermilk, it tends to become thicker and lumpier as time goes by.  If it’s at the point where it’s difficult to pour or you see large lumps then it’s probably time to throw it out.

Different color: Over time the buttermilk will start turning darker.  This is another sign that the milk is starting to break down.

Mold: Look at the buttermilk before you pour it.  Do you see any green or blue spots in it?  Mold comes in through exposure to air.

It tastes funny/losing its flavor: If you don’t see any immediate signs of the buttermilk going bad, try a taste test.  Just like with its smell, the taste of the buttermilk will change as time goes by.  It will lose its buttery flavor and start tasting sourer and sourer.

How To Store Buttermilk?

Buttermilk can be stored in the refrigerator, freezer, or in the pantry if it’s a powder.  Here are some tips to store it.

Pantry: If you store powdered buttermilk, make sure it’s in a cool, dry place without any heat or light sources around.  You want to avoid humidity since that makes the powder clump together, too.  An air-tight container is the best way to store it, which means you can use the original container or something like Tupperware.  Do NOT store liquid buttermilk like this.

Refrigerator: Keep the buttermilk as far back in the fridge as you can.  Avoid putting the milk on the door, since the door is often exposed to the warm air outside.  Once you open the container, use the milk as little as possible to minimize any contact with air.  Keep the lid tightly closed and pay attention to the “best by” date.

Can you freeze Buttermilk?

Buttermilk doesn’t exactly freeze very well; the ingredients tend to separate and the milk won’t have the same texture once thawed, but it can be used for cooking.

  • Ice cube trays work very well for freezing buttermilk. Just put a small portion into each section, wrap the whole thing in plastic wrap, and you’ll have an easy time getting the amount you need.  You can also use silicone muffin trays for larger portions
  • Another thing you can do is put it into resealable plastic freezer bags with the freezing date written on them. Some people like to combine this with the ice cube trays by popping the milk cubes out of the tray and putting them into the freezer bags
  • If you’re using a freezer bag, you can write out how much buttermilk is in each bag. This way you won’t have to worry about using too much

How to Thaw Buttermilk?

Buttermilk can be thawed out in multiple ways:

  • Place the buttermilk in a microwave-safe bowl before putting it in the microwave Set it for ten seconds on low power.
  • If you don’t have a microwave, you can place the container in water for a few minutes. Alternatively, you can move the buttermilk to the refrigerator.   Whichever option you go for, don’t forget to give it a good mixing if the ingredients have separated

Frequently Asked Questions About Buttermilk’s Shelf Life

Does traditional buttermilk have a different shelf life from cultured buttermilk?

As far as I can tell, they have the same shelf life.  Traditional buttermilk comes from making butter, so presumably, it would have a similar shelf life.  Pay attention to the “best by” date on the package it came in.

What happens if I eat or use buttermilk that’s gone bad?

Bad buttermilk doesn’t taste very good.  If you’ve kept it up to this point, the proteins in the milk will have broken down making the buttermilk unpleasant to drink.  This also goes for using it in baking.  The buttermilk could also make you sick with a bad stomachache, at least.  If it’s gone bad then definitely throw it out.

What is acidified buttermilk, and does it have a different shelf life to cultured buttermilk?

Acidified buttermilk is a substitute used for recipes, and it’s not actually buttermilk.  It’s made by adding vinegar or lemon juice to regular milk, so it has a similar shelf life, around four to seven days.

Wrap Up

The “best by” date on a container of buttermilk isn’t concrete; rather it’s when the buttermilk’s quality can’t be assured anymore.  Buttermilk degrades gradually, and so checking for signs of it going bad is always a good idea.

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