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How quickly does oat milk go bad?

Oat milk has become an increasingly popular plant-based milk alternative in recent years. Made from soaked oats and water, it has a creamy, mild flavor that makes it perfect for drinking, baking, and adding to coffee and cereal. But like any perishable food, oat milk has a limited shelf life. So how long does unopened and opened oat milk last before it goes bad?

Factors That Determine Oat Milk’s Shelf Life

Several factors impact how long oat milk will stay fresh and safe to consume:

  • Container type – Shelf-stable oat milk in aseptic cartons lasts significantly longer than refrigerated oat milk in plastic jugs or glass bottles.
  • Ingredients – Oat milk with more preservatives and stabilizers will generally last longer.
  • Processing method – High-temperature pasteurized oat milk lasts longer than cold-pressed versions.
  • Storage temperature – Refrigerated oat milk lasts longer than room temperature.
  • Time after opening – Once opened, oat milk has less time before spoiling.
  • Best by date – This is the manufacturer’s recommendation for peak freshness.

Keeping these factors in mind, let’s look at how long different types of oat milk stay fresh and what signs to look for when it’s time to throw it out.

Unopened Oat Milk

Shelf-Stable Oat Milk

Oat milk sold in aseptic cartons does not require refrigeration until after opening. Unopened shelf-stable oat milk generally stays fresh for:

– Best by date: 10-12 months
– Past best by date: 2-3 months

The best by date is simply a recommendation, not an expiration date. Shelf-stable oat milk manufacturers use a high-temperature ultra pasteurization process that allows the product to remain stable for an extended period without refrigeration.

As long as the container is not damaged in any way, unopened shelf-stable oat milk should retain peak freshness for about a year past its packaged date. After that, it remains safe to consume for several more months but may start to show some degradation in texture and flavor.

Refrigerated Oat Milk

Unlike shelf-stable versions, refrigerated oat milk needs to remain chilled right up until serving. When properly stored in the fridge, unopened refrigerated oat milk generally lasts:

– Best by date: 7-10 days
– Past best by date: 3-5 days

Since it does not undergo the same ultra high-temperature pasteurization process, refrigerated oat milk has a shorter shelf life. Keeping it chilled prevents rapid microbial growth.

Signs It’s Time to Toss Unopened Oat Milk

Unopened oat milk that shows any of the following signs should be discarded:

  • Container damage like swelling or leaking
  • Mold or slime formation
  • Off odors
  • Fizzing or spurting when container is opened
  • Viscous, clumpy, or stringy appearance

As long as an unopened oat milk container remains in good condition without these issues, it is likely still safe to consume a short time past the printed best by date. However, peak freshness and flavor diminishes over time.

Opened Oat Milk

Once opened, both shelf-stable and refrigerated oat milk have a shorter lifespan before going bad. Here is how long different types of opened oat milk generally last:

Opened Shelf-Stable Oat Milk

– Refrigerated after opening:
– 7-10 days
– Stored at room temperature after opening:
– 3-5 days

Although aseptic shelf-stable oat milk can be stored at room temperature when unopened, it must be refrigerated once the packaging seal is broken. The high temperatures used to sterilize the milk eliminate most microbes, but refrigeration is still needed to prevent microbial growth once exposed to air and prevent spoilage.

Opened Refrigerated Oat Milk

– Refrigerated after opening:
– 3-5 days

Unlike shelf-stable varieties, refrigerated oat milk already requires chilling. It should be kept refrigerated at all times, both before and after opening. The fridge temperature helps slow the growth of bacteria and mold to extend its shelf life for up to a week past opening.

Signs Opened Oat Milk Has Spoiled

Check opened oat milk for the following before consuming:

  • Sour odor
  • Tart, curdled, or stringy texture
  • Mold growth
  • Gas bubbles
  • Separation and watery appearance

If you notice any of these warning signs, discard the oat milk even if it has not exceeded the recommended shelf life after opening. When stored and handled properly, oat milk should remain drinkable for about a week past opening if refrigerated.

Here is a helpful table summarizing how long different types of oat milk generally last:

Oat Milk Type Unopened Refrigerated After Opening Room Temperature After Opening
Shelf-Stable 10-12 months before best by date
2-3 months after
7-10 days 3-5 days
Refrigerated 7-10 days before best by date
3-5 days after
3-5 days Not recommended

How to Store Oat Milk Correctly

To get the most shelf life out of oat milk and prevent it from going bad prematurely:

  • Check the best by date when purchasing
  • Keep shelf-stable oat milk in a cool, dry pantry away from direct sunlight
  • Refrigerate plastic jugs and glass bottles immediately at 40°F or below
  • Keep the cap tightly sealed
  • Wipe away any oat milk around the bottle opening before resealing
  • Keep the fridge clean and food stored properly to avoid cross-contamination
  • Refrigerate shelf-stable oat milk immediately after opening
  • Keep refrigerated oat milk chilled at all times, even after opening
  • Use clean utensils each time you dispense oat milk
  • Do not return unused oat milk from a glass back into the container

Does Oat Milk Go Bad If Frozen?

Freezing is an excellent way to extend the shelf life of oat milk beyond refrigerated timelines. Properly frozen oat milk can generally last:

– Shelf-stable oat milk: 6-8 months
– Refrigerated oat milk: 2-3 months

To freeze oat milk:

  • Ensure the oat milk container is not damaged and product is fresh
  • Leave some headspace in the container as liquids expand when frozen
  • Seal tightly and label with date
  • Freeze at 0°F or below
  • Once thawed, shake container to redistribute separation
  • Use within 5-7 days of thawing

Freezing prevents microbial growth that causes spoilage. Thawed oat milk may have some texture changes but remains safe to consume. Discard if you notice any foul odors or consistency issues after thawing.

Can You Extend the Shelf Life of Oat Milk?

You may be able to safely extend the shelf life of oat milk at home using these methods:

  • boiling – Bringing opened oat milk to a boil can kill off bacteria and extend fridge life 2-3 more days.
  • freezing – As mentioned, frozen oat milk stays fresh much longer.
  • acidification – Adding lemon juice or citric acid creates a more hostile environment for microbial growth.

However, these methods are not foolproof. Your best bet is still to follow storage guidelines and consum opened oat milk within a week. The changes in texture and flavor over time will be more noticeable.

Ultimately, oat milk is perishable like any dairy milk substitute. Both opened and unopened versions have relatively short time periods before potential spoilage can occur. Following proper storage methods and looking for signs of spoilage allows you to safely enjoy oat milk up to its best by date or within a week after opening. Just remember to treat oat milk as you would dairy milk and refrigerate it at all times for the longest lasting freshness.


Oat milk shelf life depends largely on:

– Container type – shelf-stable vs refrigerated
– Storage conditions – pantry vs fridge
– Whether it’s opened or unopened

Properly stored unopened oat milk lasts about:

– Shelf-stable: 10-12 months
– Refrigerated: 7-10 days

Once opened, oat milk should be consumed within:

– Shelf-stable: 7-10 days refrigerated, 3-5 days in pantry
– Refrigerated: 3-5 days

Keep oat milk chilled at 40°F or below, check packaging for signs of damage, and discard if you notice any changes in sight, smell or texture. Follow these tips and oat milk can remain fresh and safe to drink up to the expiration date printed on the package.