Does Oat Milk Go Bad? How To Keep It Fresh For Longer

Written by: Mike Marshall
oat milk in a jar

Oat milk is a great alternative to cow milk, at least taste-wise. But does oat milk go bad, just like dairy products?

If you’re new to using oat milk, this question is probably on your mind. 

But don’t worry, you’ve come to the right place. In this article, we’ll cover everything there is about oat milk – from shelf life to storage methods. 


Then keep reading.

How Long Does Oat Milk Last?

Just like regular milk, there are two types of oat milk sold at the grocery store: refrigerated and shelf-stable. The former must be stored in the fridge at all times, while the latter can sit in your pantry as long as it’s unopened.

Why is that, you might ask? 

Well, the reason these two types of oat milk are stored differently is all about the packaging. 

Shelf-stable oat milk is kept in aseptic packaging, so it can sit for a pretty long time at room temperature unopened. The date printed on the label says for how long oat milk will keep its optimal freshness. Usually, that’s between nine months and a year. 

However, you can also store an unopened packaging of shelf-stable oat milk in the fridge. That way, it can last a few more months past the date on the label.

Refrigerated oat milk is kept in a much thinner, chilled carton packaging, so it has to be kept in the fridge at all times. But even then, its best-before date is only a few weeks long, and it might stay fresh for only a few days after that date. Unopened, that is.

Now, the best-before date can differ between oat milk brands. 

The reason is that most manufacturers combine additional ingredients, aside from oats and milk. These include sweeteners, oil, syrups, and extracts, and are added to enhance the flavor. And it’s those bonus ingredients that affect the best-before date.

Once you open the packaging, both shelf-stable and chilled oat milk last pretty much the same. 

Generally, most manufacturers claim that’s five to nine days after opening. But again, this isn’t a given, and properly stored oat milk can be safe long after this time, with a slightly weakened flavor.

In case you make your own oat milk, forget about these numbers. Since it contains no preservative, homemade oat milk lasts much shorter. Ideally, it should be kept in an airtight jar. Juice or mason jars are your best bet. Seal it well and store it in the fridge for up to a week.

Finally, the best way to extend the shelf life of oat milk is to store it in the freezer. That way, you can keep it fresh for additional six months. Once defrosted, you should use it within the next few days. 

How To Tell If Oat Milk Is Bad?

The best-before date printed on the label is usually a good guide on whether your oat milk is still safe to consume. As soon as you open the packaging, the content will get in contact with oxygen and slowly start declining in quality. 

Don’t be surprised if you see oat milk separating. That’s normal and doesn’t have anything to do with its quality. Just shake it well before use, and the ingredients will combine again. 

However, if oat milk appears to be chunky and of a thicker consistency, that’s the kind of texture change you should be worried about. 

Before you go ham and chug down a whole carton of oat milk, check for visible clues. Pour a bit of oat milk into the glass. If you notice lumps and a somewhat creamy texture, that’s a clear sign it’s gone bad. 

Spoiled oat milk will change in color as well. If you notice it’s turning yellow or it has a much darker hue than when you first bought it, then it’s probably no longer safe for consumption. 

Another good indicator of spoilage is an off smell. Expired oat milk is easily distinguishable by its strong, somewhat acidic odor. 

Oat milk will taste tart when no longer safe for consumption. If you’re unsure whether oat milk is bad or not, you can always do a taste test. By this, I mean you should pour a few drops into the spoon. If it appears sour, spit it out and throw the packaging away.

Finally, if you’ve kept the oat milk container open, there’s a slight possibility of mold growth inside. 

Now, you don’t need me to tell you that any sign of mold appearing in oat milk is a clear sign you should discard it. 

Now if it’s past the date on the label, and none of these indicators are present, it’s very likely that oat milk is still safe to drink. However, oxygen exposure caused it to degrade over time. For that reason, its nutritional value deteriorated. 

How To Store Oat Milk?

oat milk storage

As the name suggests, shelf-stable oat milk doesn’t have to be stored in the fridge until you pop it open. As long as you’re keeping it a cool and dry place, it should stay fresh for over a year unopened. Both pantry and kitchen cabinets away from the stove are good storage options.

Once you open oat milk, you need to put it in the fridge. Not just that, the packaging must be sealed well at all times. Otherwise, exposure to air and moisture can cause it to go bad in just a day or two.

According to USDA Food Safety policy, no perishable food should be left at room temperature for more than two hours. The same goes for an opened carton of oat milk. It’s not a given that it will spoil after such a short amount of time. But you can never be 100% sure no bacteria started growing, so it’s better to just throw oat milk away.

Like other types of milk, oat milk can be frozen to last longer. But one thing you can’t do is put unopened packaging into the freezer. 

The reason is simple: sealed carton is filled with content all the way. And since it’s oat milk mainly made of water, it will freeze and expand once it reaches 32° Fahrenheit. As a result, the carton will explode and make a mess inside your freezer. 

To freeze oat milk, you should transfer it into a freezer-safe container. Make sure you leave at least an inch of space, so that oat milk can expand as it freezes.

If you need only a small amount for your cooking, you can use an ice tray instead. To do that, pour oat milk into the tray and freeze it like that. 

Just keep in mind that oat milk will settle once frozen, so you might notice a grainy texture once defrosted. For this reason, thawed oat milk might not be the best thing to add to your coffee. But you can use it for baking, as the texture won’t be apparent when mixed with other ingredients. 

You can try to get rid of grainy texture by restraining oat milk through a cheesecloth. While it won’t help you reduce the tiniest grains, it might help you make it decent enough for eating cereals, for instance.

Final Thoughts

Although it’s made mostly of oats and water, oat milk has a shelf life similar to regular milk. The unopened, shelf-stable version can last up to a year, while the chilled version is only good for a few weeks.

Once opened, oat milk should be consumed within a week. When stored in the fridge, it can probably last more than that, but it will lose in flavor and aroma. 

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I’m not a pro chef by any means, but years of tinkering inside the kitchen have taught me a thing or two about preparing delicious, healthy food. So whether you’re interested in how to properly store food, figuring out side dishes for your main course, or even learning how to use a knife properly – I've got you covered.