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In this article, I show you exactly how to freeze your leftover buttermilk and ensure that the defrosted product is (almost) as good as new.

In a rush? Here’s the short answer.

The best way to freeze buttermilk is in a freezer bag with any excess air removed. You can also freeze buttermilk in an ice cube tray for convenient portions. Buttermilk freezes for up to 3 months at best quality. Thawed buttermilk may appear grainy but this can be rectified by whisking or stirring.

The experiment

I froze several portions of buttermilk in various vessels, including an ice cube tray, an airtight container, and a freezer bag.

The aim? To find the freezing method that causes the buttermilk to split the least, with the lowest amount of effort.

The buttermilk was frozen, defrosted, and then put through a series of tests.

These include:

Blind taste tests
Texture
Appearance

fresh buttermilk in an airtight container — Fresh

frozen buttermilk in an airtight container — Frozen

thawed, grainy buttermilk in an airtight container — Thawed (unwhisked)

Can you freeze buttermilk and does it freeze well?

Buttermilk freezes really well. You may notice some separation upon thawing, but you can fix this with a quick whisk and it isn’t a problem for most applications. I recommend freezing your leftover buttermilk portioned into the quantities you most often use, making it a convenient grab-and-go for cooking or baking.

Keep the buttermilk in airtight packaging and use it within 3 months.

The buttermilk will remain safe to eat beyond 3 months, but the quality will start to deteriorate.

The separation you see is the whey and fats separating from the water.

This gives the buttermilk a ‘split’ look.

Because of this splitting, defrosted buttermilk might not be that appealing for cold applications like salad dressings, but it’s perfect for baking.

Always make sure your buttermilk is still fresh before freezing it. Gone-off buttermilk will still be gone off if you freeze it.

How to freeze buttermilk

You can freeze leftover buttermilk in zip-lock bags with the air removed or in an ice cube tray. Both options make it easy to portion your leftover buttermilk for future use. Give it a good shake before transferring into storage, and lay your baggies flat to make defrosting easier and faster.

Method

Give your buttermilk a good shake to combine (especially if it’s been standing in the fridge).
Mark your zip-lock bags with the date.
Portion your buttermilk into quantities convenient for cooking or baking.
Transfer each portion into a zip-lock bag, removing as much air as you can while sealing. You can also use airtight containers.
Lay your bags flat on a cookie tray and pop them in the freezer.
Once frozen solid, you can stack them to save space.
Use within 3 months (if possible).

Alternatively:

Transfer your leftover buttermilk into ice-cube trays (or muffin trays).
Once frozen solid, pop the cubes into a marked zip-lock bag and remove the air. To remove the air, suck it out with a straw, or dunk the open freezer bag in a bowl of water.
Use within 3 months.

Tip: one standard ice cube is equal to two tablespoons.

Marking your zip-lock bags before filling them is easier than trying to do so when they’re full.

It’s a handy way to remember to use your buttermilk!

Portioning the buttermilk out before you freeze it means you don’t end up having to defrost more than you need.

To keep more than one portion in a freezer bag, fold the bag over while it’s freezing.

This will create two blocks of buttermilk.

Removing excess air from your zip-lock bags reduces the risk of premature freezer burn and makes them easier to stack.

Thin blocks of buttermilk will thaw faster and take up less space in the freezer.

How to thaw frozen buttermilk

Your best bet is to thaw frozen buttermilk overnight in the fridge. If you’re in a hurry, you can pop it into a cold water bath (still sealed) for half an hour until it’s completely defrosted. Before using your buttermilk, give it a hearty whisk to bring it back together.

whisking buttermilk — Whisking thawed buttermilk

close up of thawed, whisked buttermilk on a spoon — Whisking thawed buttermilk

You can also use the defrost setting on your microwaves for a few seconds, but I wouldn’t recommend this unless you have no other option.

Heat can change the taste and texture of your buttermilk and make it curdle.

How long does buttermilk last?

	Opened	Unopened
Fridge	up to 14 days	7-14 days after the expiration date
Freezer	3 months	3 months

Buttermilk can last up to 14 days after opening if stored in the fridge.

But you do need to keep an eye on it.

If it goes lumpy, moldy, or develops a sour odor, it’s probably starting to go off.

The buttermilk will last longer if you ensure to keep it tightly sealed and avoid fluctuations in temperature (i.e don’t leave the fridge door open for too long).

In the freezer, you can keep buttermilk indefinitely, but it tastes best if used within three months.

Unopened buttermilk can be used 7 to 14 days after the expiration date but should also be vetted for any signs of sourness.

How can you tell if buttermilk has gone bad?

Signs that buttermilk is turning bad (apart from the obvious expiration date) include lumpiness, a strong sour smell, a change in color, and visible mold. In fact, if it starts to look different or smell than when you bought it, the chances are it’s not okay to use anymore.

Buttermilk can be tricky to judge as it always has a tangy smell and a slightly sour flavor.

However, it can cause nasty foodborne illnesses, so it’s good to keep an eye out for any signs it’s going off.

Any change in the buttermilk’s appearance and smell means its bacterial cultures are adapting and changing, which is not a good thing.

Does freezing buttermilk kill the cultures?

Freezing buttermilk does not kill its cultures. They become inactive when they freeze but will reactivate as soon as your buttermilk is thawed, provided it is thawed correctly and without direct heat.

The active cultures in buttermilk will still make perfect sour cream, cheese, or whatever you feel like!