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How Long Does Oat Milk Last?

In our modern diets, it’s true that oat milk has become a popular alternative for cow’s milk – making it suitable for those who have lactose intolerance, follow a vegan diet, or who have to avoid dairy for other health reasons. 

How Long Does Oat Milk Last?

But what exactly is oat milk, how is it made, and how long does it last once opened? 

What Is Oat Milk? 

Oat milk is a plant based milk substitute that is made by soaking oats in water to extract the plant material from within. 

This creates a substance similar to milk, which can then be used in coffee, tea, on cereals, or as a general replacement for cow’s milk. 

How Is Oat Milk Made? 

The process of making oat milk is pretty similar to other forms of plant based milk alternatives. 

The process starts by taking the oats and milling them to break down their hard outer shells.

This makes them not only suitable for use in the milk, but also better for digestion – as their unrefined form is hard and cannot be digested. 

These are then added to warm water and mixed until a slurry forms.

This slurry is then combined with selected enzymes, which create a thick, oat base for the milk to be made. 

Various other enzymes and materials are then added to the mixture.

This is to make sure that as much of the nutrients and minerals are extracted from the oats themselves and transferred into the milk.

This ensures that the goodness isn’t wasted once the oats are removed later. 

As mentioned, the oats are then removed, and this can be done through a simple process of decantation, filtration, and by spinning the remaining solution in a centrifuge. 

Once it has been separated, the mixture is then combined with other additives – such as nutrients, sweeteners, flavorings, salts, and oils to improve the taste and smell, create a specific texture, or to generally raise the nutritional value of the milk. 

Why Does Oat Milk Need To Be Refined? 

This whole refining process is a necessity, due to the fact that unrefined oat milk doesn’t contain anywhere near the same amount of nutrients and minerals as cow’s milk.

This means that the unrefined oat milk is nowhere near as healthy as traditional milk, and doesn’t have the same health benefits. 

By adding things like calcium, this means that those who (for whatever reason) cannot consume milk, can still get the associated benefits from their chosen alternative. 

How Long Does Oat Milk Last? 

How Long Does Oat Milk Last?

Of course, oat milk is still very different from cow’s milk – and these differences go all the way down to the cellular level. 

As such, things like shelf life are going to be very different from that of regular milk – which as we all know can usually stand for about a week or so in the refrigerator before it starts to go bad. 

However, the difference is not as large as you might think, with an opened bottle of oat milk usually lasting for a period of 7 to 10 days.

This is due to the ingredients included within, which can still perish when exposed to oxygen. 

How To Tell Oat Milk Is Bad?

Due to the distinct differences between oat milk and cow’s milk, you might wonder how you can possibly identify when oat milk has gone bad.

However, while the smell might not be the same as spoiled cow’s milk, it still gives indicators as to the viability of the milk. 

Check The Expiration Date

First things first, if you have any concerns about the viability of your oat milk, then the best thing to do is to check the expiration date.

This is usually printed on the bottle itself, and is a sure fire way of ascertaining whether the milk is still okay to drink or not. 

However, should the milk have been open for roughly ten days, and the expiration date has still not elapsed, then you are still probably better off disposing of the milk. 

Check The Consistency

You could also check the consistency of the milk itself.

To do this, you could either pour some into a glass, or pour a small portion into the sink, and see what it looks like in its physical form. 

If it has a lumpy and uneven texture, and doesn’t have the smoothness it normally has, then chances are it has gone bad, and you should dispose of it straight away. 

Check The Color

If the consistency is still okay, but you still have your doubts, then you could also take note of the color.

If the oat milk has spoiled, then it will have a yellow tint.

This is different from fresh oat milk, which should have the same characteristic whiteness of cow’s milk. 

Check The Smell

Lastly, if you are still unsure then the smell test is the best way to tell if it is good or not. 

While slightly different from cow’s milk, spoiled oat milk will still give off a sour smell.

This could come across as an acidic smell, or just a foul odor that isn’t pleasant to smell.

If either of these smells appear once you open the bottle, then dispose of the milk immediately. 

The Consequences

If you drink spoiled oat milk, then you will likely get stomach ache, have stomach problems, or throw up. 

Final Thoughts

And there we have it, everything you need to know about oat milk, how it is made, and how long it will last once opened. 

It’s true that oat milk has become a popular alternative for many people around the world – whether as part of a vegan diet, for those with lactose intolerance, or for those who simply do not like cow’s milk. 

However, it does have its differences to regular milk – and being aware of these can save you some serious money!

How Long Does Oat Milk Last

Oat Milk

A simple 2-ingredient, 5-minute method for making homemade oat milk! Smoothies, granola, and other recipes benefit from its naturally creamy and sweet flavor.
Prep Time: 10 minutes
Course: Drinks
Cuisine: American
Keyword: Oat Milk
Servings: 8
Calories: 47kcal


  • High-speed blender


  • 1 cup oats rolled
  • 3-4 cups water
  • 1 pinch salt
  • 1 whole date pitted (optional)
  • 1/2 tsp vanilla extract optional
  • 2 Tbsp cacao powder for “chocolate milk”, optional
  • 1/4 cup fresh berries for “berry milk”, optional


  • In a high-speed blender, combine oats, water (the lower range yields thicker, creamier milk, the higher level yields thinner milk), salt, and any additional add-ins (optional). Cover with the lid and cover with a towel to prevent spills. Mix for 30 seconds to 1 minute, or until the mixture appears to be well incorporated. It does not have to be completely pulverized. Over-blending can actually make the oat milk slimy.
  • To test the flavor/sweetness, scoop out a little amount using a spoon. Add additional dates if it’s not sweet enough.
  • Pour the mixture into a big mixing basin or pitcher that has been lined with a thin cloth or a clean T-shirt. In my experience, a repeat strain through a very tiny cloth removes any oat residues. A nut milk bag appeared to allow too much residue to get through.
  • Refrigerate in a tightly sealed container. Keeps in the refrigerator for up to 5 days (sometimes more). Mix thoroughly and serve chilled. If you heat it, it will thicken and become gelatinous. It’s great on its own or in granola, smoothies, and baked goods!



Calories: 47kcal | Carbohydrates: 9g | Protein: 2g | Fat: 1g | Saturated Fat: 0.2g | Polyunsaturated Fat: 0.3g | Monounsaturated Fat: 0.3g | Sodium: 10mg | Potassium: 64mg | Fiber: 2g | Sugar: 1g | Vitamin A: 2IU | Vitamin C: 0.1mg | Calcium: 10mg | Iron: 1mg
Tried this recipe?Let us know how it was!
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