Does Buttermilk Go Bad?

So there’s this bottle of buttermilk sitting in the fridge for a couple of weeks already. It’s a few days past the date on the label, and you’re not sure if it’s safe to use. Does buttermilk go bad?

Or maybe you’re one of the people who buy buttermilk only for cooking and baking (pancakes, anyone?). If that’s the case, you’ve probably seen it go bad too many times.

The cartons and bottles it’s sold in are quite large, and you only need a small amount for a recipe. Is there a way to extend its shelf life? You thought about freezing it, but aren’t sure how to go about that, and if it will be useful after thawing.

If you’d like to learn a bit more about storage, shelf life, and going bad of buttermilk, this article is for you.

Buttermilk in a jug
Buttermilk in a jug

How To Store Buttermilk

You should store buttermilk in the fridge, pure and simple. Like half and half, or kefir, buttermilk spoils at room temperature quite quickly.

Once you open the bottle or carton of buttermilk, make sure always to keep it sealed tightly when not in use.

The fewer temperature fluctuations, the better for this dairy product. If you expect to have it opened for more than a week, don’t store it on the fridge door, but put it somewhere in the back instead. The temperature near the door is relatively high, plus it changes each time you open the fridge.

Pouring buttermilk into a glass jug
Pouring buttermilk into a glass jug

Can You Freeze Buttermilk

If you know you won’t be able to use the leftover buttermilk before it goes bad, freezing it is an option.

Unlike butter, which freezes well, freezing buttermilk has its pros and cons. The main issue with freezing this dairy product is that it changes the texture after thawing. Like yogurt, it separates once thawed, so it won’t work in uncooked recipes or as a drink.

However, you can still use it in cooked recipes, and baking in particular. The fact that it separated isn’t noticeable in such a recipe, and the acid content stays the same so it will do its job in baking (e.g., activating baking soda).

Frozen buttermilk cubes
Frozen buttermilk cubes

When it comes to how to freeze buttermilk, I suggest using an ice cube tray. This is a tried and tested way of freezing liquids that allows you to thaw as much as you need easily. If the cubes are too small, use a muffin tin instead.

Alternatively, you can pour the buttermilk into an airtight container and chuck it in the freezer. If you choose this solution, bear in mind to leave an inch of headspace in the container. Buttermilk expands when frozen.

If you want to learn more, check out my article on freezing buttermilk.

How Long Does Buttermilk Last

Like other dairy products, buttermilk usually comes with a sell-by date. That date basically informs the seller how long they can keep the product in their inventory. It’s not an expiration date by any means. On the contrary, the buttermilk should retain freshness for about a week or even up to two weeks past that date.

That’s, of course, a rough estimate. Unfortunately, you have no idea how the buttermilk was stored before it was placed on the shelf, or if it was refrigerated at all times. Therefore, every now and then your buttermilk will go bad much sooner, even before the date on the label.

Pile of pancakes
Pile of pancakes (made with buttermilk)

Once you open the container, the degradation process accelerates slightly. Because of that, you should finish the bottle within a week or two of opening. Yes, even if the sell-by date is almost a month from now. If you expect to keep the buttermilk around for longer, it’s better to freeze it right away.

When it comes to frozen buttermilk, like with other frozen products, the sooner you use it, the better. While frozen buttermilk doesn’t spoil, its quality very slowly deteriorates. And after like 3 to 6 months of freezing you might notice that the quality is worse than it usually was. That’s a typical effect of long-term freezing.

Buttermilk (unopened)Sell-by + 1 – 2 weeks
Buttermilk (opened)1 – 2 weeks

Please note the periods above are estimates. Plus buttermilk is a product that requires refrigeration, so if it was mishandled before it got to you, it would go bad much sooner.

Buttermilk in jug top down
Buttermilk in jug top down view

How To Tell If Buttermilk Is Bad

Deciding if buttermilk is bad isn’t exactly hard science. Of course, there are some sure signs that this dairy product is spoiled. Mold on the surface or on the neck of the bottle or carton is one. A thick, chunky texture that makes it difficult or even impossible to pour is another. And there are changes in color or an off smell that also scream “spoiled!”.

As usual, there are also more subtle changes to look out for. For example, over time the smell and taste become sourer and less buttery. And there’s no good way of telling if it’s sour enough to call it spoiled and get rid of it. Here things come down to personal preference.

Pouring buttermilk into an ice cube tray
Pouring buttermilk into an ice cube tray

Because of that, if you’re about to use buttermilk that already sits in the fridge for over a week, check its quality beforehand. If you find it good enough, feel free to use it. If it’s not up to your standards, cut your losses and throw it out. There’s no point in ruining a perfectly good dish with sour buttermilk.

Last but not least, if this dairy product is a month past the sell-by date or opened for over 2 weeks, just throw it out. Technically, it could still be safe to eat, but there’s no point in risking foodborne illness. As I often remind you: better safe than sorry.