Does Oat Milk Go Bad? How Long Does Oat Milk Last?

Oat milk is a dairy-free alternative that is full of nutrients like fiber and vitamin B.  You can store it on the pantry shelf or in the fridge, but how long does it last there?  Read on and find out.

Quick Answer

How long oat milk lasts depends on if it’s the kind that comes from the dairy section or found on the regular shelf, and whether the container has been opened.  The kind that’s found on the shelf, or the shelf-stable kind, can last one to three months after the “best by” date.  The cold type of oat milk lasts five to seven days after its “best by” date if unopened, and four to seven days after you opened it.


Here’s a handy guide to storing oat milk, making it last as long as possible, and how to know when it’s time to throw it out.

Does Oat Milk Go Bad? How Long Does Oat Milk Last?

Oat milk’s “best by” dates and how long it lasts can vary depending on the type you’ve bought.  Different companies tend to use different ingredients or recipes.  Always check the date before you buy it.

How Long Does Oat Milk Last Outside?

Certain kinds of oat milk are sterilized as they’re packaged, making them shelf-stable.  This means you can store them in the pantry, at least until they’re opened.  Shelf-stable oat milk lasts anywhere from one to three months after its “best by” date.

The container needs to be kept away from any sources of light, and especially heat.  Generally, the back of any cupboard or pantry works fine.

If you’re using the kind of oat milk that must be kept cold or if you’ve opened a container of the shelf-stable oat milk, you want to put it back in the refrigerator within two hours.

How Long Does Oat Milk Last in the Fridge?

If you haven’t opened it yet, refrigerated oat milk, the kind you see in the dairy section lasts five days to one week past its “best by” date.

When you open it, the seal is broken and airborne contaminants can get in.  This is why your milk only lasts around four to seven days after it’s been opened.

Unlike store-bought oat milk, homemade oat milk doesn’t have access to the same preservatives.  So, any oat milk made at home will only last around five days when stored in the fridge.  But on the bright side, you can always make more with the right ingredients!

How Long Does Oat Milk Last in the Freezer?

Oat milk, both shelf-stable and non, lasts around six months in the freezer, but the longer it’s frozen the more its texture will change.  The ingredients settle and it becomes grainy.

You must store oat milk at a constant temperature, so keep it in the back of the freezer, away from any light or heat sources and smelly foods.  Make sure that there is around an inch or so of extra room in the container because the milk expands when it’s frozen.

Don’t forget to use a label or marker to write down the date you froze it, just in case you forget what day you put it in and leave it for too long.

Oat milk can last anywhere from a few days to months if you store it in the right place, but it doesn’t last forever.  The best thing you can do is check it before you use it for any signs that it’s gone bad.

How To Tell If Oat Milk Has Gone Bad

Oat milk doesn’t go bad all at once; it gradually starts showing signs and eventually becomes too gross to eat.  Here is what to look for:

Smell: Take a whiff of the oat milk.  Does it smell off?  If it doesn’t smell good, then it’s time to toss it.  I’ve also heard of oat milk losing its smell altogether when it goes bad, although I’ve never personally experienced this.

Taste: When in doubt, try the taste test.  Oat milk starts tasting sour as the milk breaks down.

Mold: If you see any green or blue spots, that means that airborne spores have gotten into the milk, usually from leaving the container open or from small defects in the packaging.

Changing color: Oat milk is normally a creamy or light brown color, but it turns yellow when it spoils.  If you see yellow spots or if it’s a solid yellow, throw it out!  As a side note, I hear that some brands of oat milk are more of a yellowy color than the rest.  If that’s the case, check the “best by” date and look for other signs of decay.

Lumps: Does the milk seem thicker, or are there any lumps in it?  When oat milk goes bad, it gets thick up to the point where the milk starts to congeal and you’ll see lumpy patches.

How To Store Oat Milk?

No matter where you store it, oat milk needs to be kept in an air-tight container, usually, the original container works the best.

Before opening: You need to keep oat milk unopened until you’re ready to use it.  Depending on which kind you got, you can store it in a pantry or in the refrigerator.  Storing unopened oat milk in the freezer isn’t a good idea, since oat milk expands when it freezes, running the risk of the container breaking.

After opening: When you open oat milk, it needs to be stored in the refrigerator or freezer.  Even the shelf-stable kind.  The milk should not be drunk straight from the container, since that promotes germ growth and mold, but poured into a cup to use.  Don’t forget to put the cap back on tightly when you’re finished with it.  If the container doesn’t have a replaceable cap, you can pour the milk into an air-safe container before putting it into the fridge.

Can You Freeze Oat Milk? How?

Oat milk can be kept in the freezer and will stay fresh for months.  Here are some tips for freezing it.

  • You can divide the milk into smaller portions by pouring it into an ice cube tray before it’s frozen. Then wrap the ice cube tray in plastic wrap or wait until the milk is frozen and put the cubes into freezer-friendly plastic bags.  This means smaller portions which are easier to use and thaw
  • For larger portions, use an air-tight container. Generally, the original container will do if it’s got a resealable opening.  Leave some room for the milk to expand, too
  • Don’t thaw the milk out until you’re ready to use it. Oat milk can’t be re-frozen after it’s thawed out
  • Oat milk becomes grainy when it’s frozen, due to the ingredients settling. If you want to take some of the graininess out, you can strain the thawed milk through a cheesecloth

How To Thaw Oat Milk?

The best way to thaw oat milk is to move it from the freezer to the refrigerator.

  • Leaving the milk in the fridge overnight is the most convenient way to thaw it. Then in the morning, it’ll be ready to use
  • Thawed oat milk is a better choice for cooking than for drinking or flavoring drinks due to the grainy texture

Frequently Asked Questions About Oat Milk’s Shelf Life

Do oat milk’s ingredients separate when frozen?

Basic oat milk usually doesn’t separate in the freezer, since the ingredients have blended well.  It can separate when placed in hot, acidic drinks like coffee or tea or other similar situations.  The ingredients will also settle towards the bottom, requiring the container to be shaken.  Some brands have added ingredients like rapeseed oil that tends to separate when frozen, which you can fix by whisking the thawed milk ingredients back together.

How do I tell if oat milk is shelf-stable?

Normally you find shelf-stable oat milk on, well, the shelf at the supermarket and non-shelf stable in the dairy or frozen foods department.  If you aren’t sure and the milk has been out of the fridge for long enough that it doesn’t feel cold, take a look at the package.  If it says something like “keep refrigerated,” then it’s the kind that you need to keep cold and should probably be thrown away.  Shelf-stable oat milk usually has “refrigerate after opening” on the package.

Wrap Up

As a final precaution, all of the dates given here are estimations.  Maybe your oat milk won’t last as long as predicted, maybe it will last even longer.  If you aren’t sure about the milk, it’s wiser to err on the side of caution and throw it out.

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