Does Freezing Sauerkraut Kill Probiotics or Good Bacteria?

Fermented sauerkraut can be a rich source of natural probiotics that can be good for your body. But you might be wondering whether you can freeze it to prolong its shelf life and whether the probiotics will survive being in the frozen state.

So, how do you freeze sauerkraut to ensure the probiotics aren’t killed off in the process, and why is it necessary to do that?

Let me discuss more of that below.

Can You Freeze Sauerkraut?

Technically, it’s so easy to simply answer “yes” to this question right off the bat.

After all, most foods can be frozen – and they do last longer when you do that. However, many people who tried freezing sauerkraut say that they didn’t like eating the thawed food because the vegetables (usually cabbage) lose the crunch and turn soggy after the process.

For many, the crunchiness is key to enjoying their sauerkraut.

Others discover that cooking sauerkraut before freezing can help keep the crunchiness once it’s frozen.

Still, both situations make us wonder whether the good bacteria in these products survive the processes.

Let’s dig deeper into these processes below, particularly when it comes to freezing this probiotic side dish.

Does Freezing Sauerkraut Kill The Probiotics or Good Bacteria?

Scientists have long been studying how bacteria, especially the useful ones used in fermentation and other processes, react when they’re frozen or heated.

In a study published as early as 1955 in the Journal of Bacteriology, researchers discovered that bacteria can actually survive freezing.

However, they theorized that the percentage of survival will depend on the initial concentration.

The researchers of this study also learned that second freezing is usually lethal to most bacteria, with most of the populations dying no matter the length of the first freezing or the intervals between the first and second freezing.

That’s good to note because it only means that although it’s alright to freeze sauerkraut (and other bacteria-containing products) the first time, doing so the first time will surely kill all the bacteria left.

When freezing sauerkraut, however, it’s also a good idea to do the freeze-drying method instead of the usual way of putting the jar in your freezer. Slow freezing the regular way might kill the probiotics. (more of this below)

Still, you might have some questions about freezing specific sauerkraut products in certain situations. Let’s take up each one below:

Does freezing homemade sauerkraut kill probiotics?

Whether homemade or commercial, bacteria in sauerkraut can still survive freezing.  However, homemade sauerkraut usually doesn’t contain preservatives or cryoprotectants that some manufacturers might use to help prolong the product’s shelf life and protect the probiotics during freezing.

So, it’s possible that freezing homemade sauerkraut might kill the probiotics. This is especially the case with sauerkraut with less concentration of probiotic bacteria.

Can you freeze sauerkraut from a can?

Yes. Just as explained above, freezing sauerkraut straight from the can is fine and safe. However, we suggest freeze-drying instead of the regular way of simply letting it slowly freeze.

Also, it’s very important to first transfer the canned sauerkraut into a freezer-safe container because the can might burst when the liquid expands.

Can you freeze cooked sauerkraut?

Yes, you can freeze cooked sauerkraut. However, take note that cooking or any heat application kills probiotics. So, while you can still enjoy delicious sauerkraut after thawing, it’s likely that this no longer has any probiotics left. 

If you’re after the health benefits of the probiotics in sauerkraut, then you shouldn’t cook it, regardless of whether you’re planning on freezing it or not. 

Can you freeze bagged sauerkraut?

Yes. Still, like the canned sauerkraut, we recommend freeze-drying.

What’s The Best Way To Freeze Sauerkraut?

Freeze-drying remains the best way of freezing sauerkraut because it gives your probiotic bacteria more chance to survive.

However, freeze-drying machines can be extremely costly. That can be a huge setback for people who are only planning to freeze-dry a few batches of food or even just their sauerkraut from time to time.

The good news is that you can use this life hack to flash-freeze your sauerkraut without using an expensive freeze-drying machine:

• Step 1. Transfer your sauerkraut into an airtight, freezer-friendly container. Ensure that you leave space on top for liquid expansion so your container won’t burst.
• Step 2. Cover tightly and seal your container. 
• Step 3. Label with the freezing date or the expiry date (approximately 12 months from the freezing date).
• Step 4. Prepare a large bucket and enough ice to cover the space.
• Step 5. Put a layer of ice inside the bucket then carefully but quickly put the sauerkraut container inside.
• Step 6. As quickly as possible, fill the rest of the bucket with ice.
• Step 7. Add water and a few tablespoons of salt inside the bucket.
• Step 8. Cover the bucket and let the sauerkraut container sit for at least 15 minutes.
• Step 9. Remove from the bucket and immediately put in the freezer.

Some tips to consider:

• Instead of using a big jar, freeze your sauerkraut in serving-size portions. This way, you only need to thaw what you’ll need. Remember that a second freeze can kill all the probiotics, so you have to avoid returning the thawed food back to your freezer
• Immediately transfer the flash-frozen container to your freezer because if it gets kept at room temperature for a while, that can already be considered as the first freeze. Putting it in the fridge will now count as the second freeze – and is likely to kill your probiotics

What Temperature Kills Probiotics In Sauerkraut?

Probiotics can die at around 115 °F (46 °C). That’s actually a low temperature, considering that water boils at 212 °F (100 °C).

That’s why it isn’t a good idea to cook sauerkraut before freezing it.

Based on the 1955 study above, the probiotics in sauerkraut survived first freezing – and that’s considering that the freezing point of water is at 32 °F (0 °C) and most freezers have this temperature.

But in the study, the researchers went as low as -7.6 °F (-22 °C).

How Long Do Probiotics Last In Sauerkraut?

This can actually depend on a lot of factors, including the actual probiotic concentration and how the product is handled or stored.

It’s quite possible that the probiotic concentration will increase and remain viable for 1-3 months. And as long as you haven’t opened a sealed container, it can even sit in your cupboard until the expiry date printed on the label.

An opened sauerkraut container should be consumed within 24 hours after opening if you don’t put it in the fridge.

If refrigerated, your sauerkraut can last for up to a week after opening – and the probiotics in them will survive at around the same period.

If fermented and flash-dried properly, frozen sauerkraut can last up to 12 months in the freezer. Thawing your frozen sauerkraut can awaken the dormant probiotics. Their new shelf life will follow the rules above.

Still, there’s really no telling whether the probiotics will survive the freezing if you didn’t do things right or if other factors might have affected them during freezing.

Let’s discuss the advantages and disadvantages of freezing this side dish below so you can decide whether you should do it.

Pros and Cons of Freezing Sauerkraut

Whether you bought sauerkraut or made some at home, it is unlikely that you will consume the entire container in one sitting (unless you’re serving it at a party, of course).

So, what to do with leftover sauerkraut?

Freezing is a popular answer, but let me discuss its pros and cons first before you decide on doing that.

Pros

• Freezing prolongs the sauerkraut’s shelf life to around 12 months instead of just a few months.
• If done correctly, such as freeze-drying or flash-freezing, most of the probiotics in the sauerkraut will be dormant during their storage in the freezer. They’ll be reactivated once the sauerkraut is thawed.

Cons

• If not done correctly, such as simply letting the sauerkraut slowly freeze, the probiotic bacteria can die. Although the sauerkraut won’t spoil if the bacteria die, you will no longer benefit from the probiotics if they’re dead.
• The sauerkraut can lose its crispiness and become soggy after getting frozen and thawed.
• Some people suggest cooking the sauerkraut before freezing it to maintain its crispiness after thawing. However, cooking can kill off the probiotics.

Still, if you’re only freezing the sauerkraut to prolong its shelf life but not really after its probiotic content, then there’s no stopping you from doing it. 

You can always just find other, more stable, and reliable probiotic sources while enjoying your frozen sauerkraut.

FAQs

How Long Can You Freeze Sauerkraut?

Frozen sauerkraut can last for up to 12 months.  While it might still last a few weeks or months after the 1-year mark, it’s advisable to always check whether the thawed sauerkraut isn’t spoiled before you eat it.

Also, while it might still look fine, it’s best to throw away sauerkraut that’s been in the freezer for over 1.5 years.

How To Thaw Frozen Sauerkraut?

In thawing sauerkraut, it’s best to avoid using the microwave. Instead, you can simply let it sit at room temperature for a few hours.

Remember that refreezing thawed sauerkraut will kill off most of the probiotic bacteria left. To preserve your stock, thaw only what you need. The best way to achieve that is to freeze your sauerkraut in portion sizes for use in one meal or one day.

How Long Does Thawed Sauerkraut Last?

For best results, consume thawed sauerkraut immediately. If there’s still some left, don’t refreeze. It can still be fine on your next meal, but make sure to discard or consume it within 24 hours after thawing.

How Long Can You Keep Sauerkraut In The Refrigerator?

Sauerkraut can remain fresh and fine for up to 6 months in the fridge (not the freezer).

However, it’s very important to always keep the jar tightly closed and to use a clean, unused spoon in scooping the contents of your sauerkraut container. 

Sauerkraut can still spoil even if stored inside the fridge if pathogenic or other types of bacteria contaminate the container (possibly from a used spoon).

Does Cold Sauerkraut Have Probiotics?

Yes. It’s still possible for cold sauerkraut to contain probiotics as long as:

• It wasn’t cooked before putting in the fridge
• It was stored correctly and flash-frozen or freeze-dried properly before being placed in the freezer
• It wasn’t frozen and thawed for the second time

Does Canning Sauerkraut Kill Probiotics?

Yes. Although canning can prolong the shelf-life of most food items, it can also potentially kill the probiotics in your sauerkraut.

Most canning processes undergo a process called pasteurization. This is designed to kill any pathogenic bacteria, viruses, or other microorganisms that can cause spoilage. Sadly, this process can’t distinguish between these bad microorganisms and the “good bacteria” in probiotics.

Canned sauerkraut is still safe to eat, of course. However, don’t expect that it still contains any live microorganisms.

That means that you can still enjoy canned sauerkraut but it can’t be a source of probiotics.

We recommend making your own sauerkraut and flash-freezing them before storage instead of canning them.

Wrap up

In conclusion, freezing sauerkraut can help preserve probiotic bacteria, as long as you use the freeze-drying method. However, this process is only viable once; repeating the process may kill most or all of the bacteria present.

Some people prefer to keep their sauerkraut in their refrigerator rather than freeze it in order to retain its crunchiness and ensure that probiotics remain alive for consumption. Whether homemade or store-bought, sauerkraut can provide a rich source of natural probiotics that are beneficial to your body if done safely.