Oat milk has become an increasingly popular plant-based milk alternative in recent years. Made from soaked and blended oats, oat milk has a creamy texture and mild flavor that makes it suitable for drinking, cooking, baking, and more. But like other perishable foods and beverages, oat milk does eventually spoil. So how can you tell if your oat milk has gone bad, and what is the actual shelf life of oat milk? Here we’ll explore the signs of spoiled oat milk, how long it lasts unopened versus opened, and how to extend its freshness.
What are the signs that oat milk has gone bad?
Oat milk, like other plant-based milks, can go bad once it passes its expiration date or if not properly stored. Here are some of the most common signs that your oat milk has spoiled:
Sour smell and taste
Fresh oat milk should have a mild, creamy aroma and flavor. If it develops an unpleasant sour or acidic smell and taste, that’s a sign it has spoiled.
Clumpy texture
Properly mixed and stored oat milk will have a smooth, creamy consistency. If you notice clumps, sliminess, or curdling, the oat milk has likely gone off.
Mold growth
Like other dairy and plant-based milks, oat milk can develop mold if left for too long. This appears as fuzzy spots or discoloration on the surface. Mold is a clear indication milk has spoiled and should be discarded.
Gas or bubbling
Fermentation due to spoilage can cause carbonation, gassiness, or bubbling in plant-based milks. If you notice this upon opening your oat milk, it’s a sign it’s gone bad.
Separation
Oat milk contains both water and oat solids. Over time, these can separate with a layer of clear liquid at the top. While not necessarily harmful, separation is a sign the milk is older and likely soon to spoil.
How long does unopened oat milk last?
The shelf life of oat milk depends on whether it’s unopened versus opened, how it’s stored, and the expiration date. Here’s how long oat milk typically lasts:
Unopened oat milk
Sealed, refrigerated oat milk generally stays fresh 5-10 days past its printed “best by” or expiration date on the package. So if the date is January 1st, you can safely drink unopened oat milk around January 10-15 in most cases.
Some ultra-pasteurized oat milk may last 2-4 weeks past its printed date when kept sealed and refrigerated. Always check for signs of spoilage before consuming, even if within date.
Unopened, shelf-stable oat milk can be stored in the pantry up to 6-8 months past its printed expiration date before opening. Once opened, it should be refrigerated and used within 7-10 days.
Opened oat milk
Once opened, oat milk will only last about:
– 5-7 days in the fridge
– 1 week in the fridge if ultra-pasteurized
– 6 months unopened in the pantry
So make sure to write the opening date on your oat milk carton, and use within a week once opened for best quality and food safety.
Does oat milk last longer than dairy milk?
Oat milk generally has a slightly longer shelf life compared to dairy milk. Here’s how their freshness periods compare:
Dairy milk
– Unopened – 5-7 days past “sell by” date
– Opened – 5-7 days
Oat milk
– Unopened – 7-10 days past “best by” date
– Opened – 5-7 days (up to 1 week if ultra-pasteurized)
The longer shelf life of oat milk compared to dairy milk is due to differences in processing and naturally occurring enzymes. The oats in oat milk don’t contain the same dairy sugars and proteins that can shorten freshness periods for animal milk.
Does refrigerating oat milk make it last longer?
Yes, proper refrigeration is key to maximizing the shelf life of opened and unopened oat milk. Here’s how refrigeration keeps oat milk fresher for longer:
- Slows microbial growth – Cold temperatures inhibit the growth of bacteria, mold, and other spoilage microbes.
- Prevents separation – Chilling helps keep the oat milk emulsified, preventing the oat particles and water from separating.
- Slows enzymatic reactions – Refrigeration slows down chemical reactions and enzymatic processes that can cause off-flavors.
- Extends nutrient retention – The cold helps retain heat-sensitive vitamins like vitamins C and B12.
For longest freshness, store oat milk at 40°F (4°C) or below immediately after purchasing. Keep it chilled until ready to use.
Do different oat milk brands last longer?
There can be some variability in how long different brands or types of oat milk last. Here are some factors that can affect oat milk’s shelf life:
- Fat content – Full-fat oat milks may degrade faster than low-fat versions due to potential lipase enzyme activity.
- Processing method – Ultra-pasteurized milk lasts 1-2 weeks longer opened versus conventionally pasteurized oat milk.
- Packaging – Aseptic cartons keep out more oxygen and light to prolong freshness compared to plastic bottles.
- Preservatives – Some brands may use natural preservatives like citric acid that help extend shelf life.
So while most oat milks have similar timelines, certain qualities like higher pasteurization temperatures or preservative use can help lengthen how long it stays fresh. Check labels and storage guidance.
How to tell if opened oat milk is still good?
Once you’ve opened and started using a carton of oat milk, how can you tell if it’s still safe and hasn’t spoiled? Here are some tips for evaluating the freshness of opened oat milk:
- Do a smell and taste test – Off smells, sourness, or bitterness means it’s no longer fresh.
- Inspect the color – Significant darkening or graying could indicate spoilage.
- Check the texture – It should be smooth and creamy, not curdled, slimy, or watery.
- Look for expiration dates – Write the open date on the carton and discard after 5-7 days.
- Observe separation – Some separation is normal but excessive wateriness means it’s deteriorating.
- Avoid mold – Any fuzz, spots, or film means it’s past safe use.
Trust your senses – your eyes, nose, and tastebuds. If anything seems “off”, err on the side of caution and discard the oat milk to prevent foodborne illness.
Does freezing extend the shelf life of oat milk?
Freezing is an excellent way to extend the shelf life of oat milk beyond typical refrigerator times. Here’s how freezing keeps oat milk fresher for longer:
- Halts microbial growth – Freezing temperatures stop spoilage microorganisms in their tracks.
- Slows chemical reactions – Enzymatic and oxidative reactions are essentially “paused” when frozen.
- Avoids separation – Freezing helps maintain emulsion, preventing water and solids from separating.
- Minimizes nutrient loss – Vitamins are better retained compared to refrigeration alone.
Properly frozen oat milk can maintain quality and freshness for up to:
– 6 months in a deep freezer at 0°F (-18°C)
– 2-3 months in a self-defrosting freezer at 32°F (0°C)
Freeze oat milk in airtight containers and leave at least 1/2 inch headspace for expansion. Thaw overnight in the fridge before using.
How to store oat milk to maximize freshness
To get the most shelf life out of your oat milk, follow these storage tips:
- Refrigerate after opening – Keep opened oat milk chilled at 40°F (4°C) or below.
- Seal containers tightly – Prevent oxygen exposure that can degrade quality.
- Limit light exposure – Store in opaque containers out of direct light.
- Avoid temperature fluctuations – Don’t leave oat milk out on countertops.
- Check “sell by” dates – For best flavor and texture, use unopened milk within 5-7 days of the date.
- Freeze for longer storage – Freeze up to 6 months for retention of freshness.
Following the proper storage methods helps prevent microbial spoilage, separation, and nutrient loss.
Can you make oat milk last longer?
There are a few simple tricks that can help your oat milk stay fresher for longer:
- Add lemon juice – The acidity helps inhibit microbial growth.
- Store in smaller containers – Less air exposure once opened.
- Use ultra-pasteurized – The higher heat processing gives it longer shelf life.
- Add DHA/omega-3s – These healthy fats are natural preservatives.
- Keep very cold – Store at 34-37°F (1-3°C) to slow spoilage.
- Freeze in portions – Thaw just what you need as you go.
Getting the longest shelf life out of your oat milk comes down to following best storage practices and avoiding contamination once opened.
Can you use oat milk past the expiration date?
It’s generally not recommended to use oat milk past its printed expiration or “best by” date on the package. However, you may have some leeway if the milk was properly stored:
- Unopened, refrigerated – 5-7 days past date
- Unopened, shelf-stable – Up to 6-8 months past date
- Opened – Don’t use more than 7-10 days past date
Always inspect and smell oat milk before consuming to check for signs of spoilage like off-colors, curdling, mold, etc.
As oat milk ages past its prime freshness, its texture and flavor quality goes down. While unlikely to make you sick immediately, very old milk may not taste great. Freezing previously opened oat milk can allow you to safely use it past date as long as frozen and thawed properly. But for best quality, it’s generally better to stick to “best by” dates.
In what ways can oat milk go bad?
There are several different ways that opened and unopened oat milk can spoil, including:
- Microbial spoilage – Bacteria, mold, and yeast growth.
- Lipase activity – Enzymes degrade milk fats causing rancidity.
- Protein degradation – Proteins break down causing taste/texture issues.
- Oxidation – Exposure to oxygen causes vitamin loss and rancidity.
- Separation – Water and solids divide resulting in thin, watery milk.
Storage at improper temperatures, age, damage to packaging, and contamination introduce the factors that can lead to oat milk going bad by a variety of mechanisms.
Is it dangerous to drink oat milk past the expiration date?
Drinking spoiled oat milk that is significantly past date and showing signs of spoilage can potentially make you sick. Here are some risks of consuming bad oat milk:
- Foodborne illness – From microbial growth of bacteria, molds, and yeasts.
- Off-flavors – Rancidity from fat breakdown.
- Gastrointestinal issues – Cramps, nausea, and diarrhea.
- Allergic reactions – To high histamine levels and microbial contaminants.
While it’s not inherently dangerous to drink oat milk a few days past its prime, you generally want to avoid consuming oat milk that:
- Has developed a foul odor, taste, appearance
- Is more than 7-10 days past its printed date
- Has any mold spots or growth
- Was not properly refrigerated
- Was left out unrefrigerated for over 2 hours
- Has abnormally separated or shows curdling
When in doubt, remember it’s better to be safe and discard old or questionable oat milk to avoid getting sick.
Conclusion
Like other plant-based milks, oat milk does eventually go bad once it surpasses its shelf life or isn’t stored properly after opening. Signs that your oat milk has spoiled include sour smells, changed texture, separation, mold growth, and bubbling or gassiness.
To maximize your oat milk’s shelf life, store it sealed in the fridge and use within 5-7 days of opening. Drink unopened oat milk within 5-10 days of the “best by” date for optimal freshness. Freezing also extends the shelf life of oat milk up to 6 months. While it likely won’t make you immediately ill, consuming oat milk past its prime can result in unpleasant flavors and textures. So check packages for dates, store oat milk properly, and rely on your senses to determine if your oat milk is still good to enjoy!
