The dish of sauerkraut is one of European origin wherein shredded cabbage and various other vegetables are fermented together to produce a distinctly sour and unique taste, making it high in demand in countries such as Germany, wherein it is assumed to have first been created.
While sauerkraut is often fermented in controlled temperatures and subsequently stored in air-tight containers such as glass jars, their shelf-life and relative shelf stability is significantly impacted once the sauerkraut has been exposed to the elements, and as such often requires extraneous forms of preservation.
Sauerkraut may be frozen, though there are several drawbacks to doing so and as such it is important to fully prepare the sauerkraut for the process of freezing. If you are unwilling or otherwise unable to prepare the sauerkraut as necessary, however, there are a multitude of other preservation options that may keep sauerkraut edible for some time.
As an added precaution, the microorganisms responsible for the fermentation of sauerkraut will also be killed or otherwise rendered inert once frozen, therefore it is best to only freeze sauerkraut after it is finished fermenting.
What Do You Need to Freeze Sauerkraut?
Freezing sauerkraut is relatively simple in comparison to preserving other organic produce by this method, as all that is required to do so are several resealable plastic pouches or freezer bags as well as a suitably large enough container made of a freezer safe material, such as treated plastic or metal.
How to Freeze Sauerkraut
In order to begin freezing sauerkraut, first allow it to cool off completely in the case that it has recently been heated on the stove. This will prevent steam from forming, subsequently creating frost on the inside of the containers and the freezer itself.
Spoon your desired serving size into separate plastic pouches or freezer bags. The sauerkraut is separated in this manner so as to remove the need to defrost the entire batch of sauerkraut when you choose to remove it from the freezer, as refreezing thawed sauerkraut may be disastrous for its quality and shelf-life.
Squeeze as much air out of each bag as possible and place them within the secondary freezer-safe container, ensuring that none are crushed or otherwise being squeezed, as this may cause rupturing when the liquid within the bags expands during freezing.
Place the container of sauerkraut in the deepest part of your freezer, though any area of the freezer is perfectly suitable, as the secondary container will act as an excellent insulator to freezer burn.
Stored in this way, sauerkraut will last for up to half a year if left undisturbed.
What is Fermented Food?
Fermentation, in its culinary form, is simply the biological conversion of sugar compounds to ethanol alcohol and certain other hydrocarbon byproducts of the fermentation reaction. This conversion process recruits the aid of certain types of fungal cultures or bacterial species that normally consume the sugar and release the desired alcohol as waste shortly after.
In the case of sauerkraut, lactobacillus bacteria or similar microbial cultures are introduced to shredded cabbage and other vegetables in a temperature-controlled environment so as to induce this fermentation conversion.
This bacterial or fungal sugar conversion is further facilitated by keeping the reaction in an anaerobic environment, insulating it against significant movement of new oxygen by keeping the sauerkraut in a tightly sealed container with holes poked within so as to prevent the container from rupturing as carbon dioxide is produced as a byproduct.
How Does Fermentation Affect Shelf-life?
Because of the fact that the nutrients within food that is being fermented is already being consumed by certain bacterial or fungal cultures, it becomes difficult for external cultures of microbial life to also colonize the vegetables, therefore extending the shelf-life of the food while it is being fermented.
However, even after the fermentation process has been paused either through freezing or exposure to significant levels of oxygen, the fermented food is still benefiting from an increased length of shelf-life owing to the fact that certain byproducts of this chemical change create a hostile environment for other forms of bacteria or fungi.
This is further facilitated by the increase in relative acidity of the medium in which the food has been fermented, usually that of water or similar fluids that are not normally resistant to microbiological life. In addition, the fact that the majority of fermented foods are kept in sealed containers also helps its shelf-life by providing insulation against the environment.
How Long Does Sauerkraut Last at Room Temperature?
The particular length of time at which sauerkraut may last in the pantry or kitchen cupboard will depend on whether it has been purchased from a sauerkraut manufacturer or if it has been fermented and packaged within your own home.
Manufacturing companies often thoroughly sterilize their workplaces and factories in order to reduce the presence of foreign contaminants and microbiological lifeforms. Apart from this, these same companies also incorporate certain chemical compounds or materials that lengthen the shelf-life of the sauerkraut, resisting the invasion of foreign microbes and making the fermented dish more resistant to the elements.
Therefore, in the event that your particular sauerkraut has been manufactured as opposed to made at home, it will last for up to a month after its best-by date, most likely printed somewhere on the container.
However, homemade sauerkraut will possess a much shorter shelf-life, and as such may only last for up to one month before showing signs of spoilage.
Keep in mind that certain brands or types of sauerkraut require refrigeration and must not be kept at room temperature. A good way to tell if your particular type or brand of sauerkraut requires refrigeration is to see whether it was originally stored in a refrigerated environment prior to purchasing. When in doubt, placing the sauerkraut in the refrigerator will not hurt.
Should You Refrigerate Sauerkraut?
Regardless of the type or brand of sauerkraut that you possess, choosing to refrigerate them is likely the best option for short term storage, so long as the sauerkraut has completed its fermentation process or is close to the completion of it.
This is due to the fact that the microbial life responsible for the fermentation conversion of the sauerkraut’s sugar will both be slowed and deactivated when placed in refrigerator temperatures. This means that, whatever state of fermentation the sauerkraut is in prior to refrigerating, it will likely stay that way until spoiling or subsequently removed.
Therefore – yes, sauerkraut should be refrigerated, though certain steps must be followed in order to prevent premature spoilage or any other untoward outcomes related to the quality of the fermented vegetables.
If your sauerkraut was purchased from a grocer or retailer, it is best to leave it sealed within its original container so as to extend its relative shelf-life for as long as possible.
However, if your sauerkraut is homemade or has otherwise been purchased in a package that is now unusable, simply drain the sauerkraut and any fluid with it into a resealable air-tight container made of a non-absorbent material such as glass, ceramic or treated plastic.
Sauerkraut stored in this way or in its original package after opening will last up to six months before showing signs of spoilage. If left still sealed within the packaging it was first purchased in, however, it may last for up to three months after the best-by date printed on said packaging.
Why Should Sauerkraut be Frozen?
Though sauerkraut is relatively stable when placed beneath the stressors of a freezing cold environment, it is still viewed as a last resort for truly long-term storage owing to the fact that it may lose some of its quality if stored improperly.
Therefore, sauerkraut should only be stored in situations wherein large volumes of it cannot possibly be consumed in a reasonable amount of time, even if otherwise preserved through the use of other methods such as refrigeration or even storage in the pantry.
This, apart from the time and space utilized in freezing the sauerkraut, is the wisest course of action as frozen sauerkraut often needs to be defrosted overnight prior to use, unless otherwise incorporated into a heated and cooked dish.
What Happens If You Freeze Sauerkraut?
Unlike other vegetables, sauerkraut freezes rather well, with only a minimal degradation in quality and no loss of flavor, even if frozen for extended periods of time. This is due to the fact that, despite its high moisture content, sauerkraut’s vegetables are small enough to suffer little damage as water within their cellular structures expands.
However, it is during the thawing process at which sauerkraut may experience the largest degradation in its textural and visual quality.
It is important to both control the rate at which the sauerkraut’s internal temperature is increased as well as the nature of which this increase occurs, for if the sauerkraut is heated too quickly or using the improper methods it will likely lose its crunchy texture and develop a pale or washed-out coloring.
1. Yu Wang 1, Jérôme Delettre et al. (June 2005) “Influence of cooling temperature and duration on cold adaptation of Lactobacillus acidophilus” UMR Génie et Microbiologie des Procédés Alimentaires
2. Vethachai Plengvidhya,§ Fredrick Breidt, Jr.,* Zhongjing Lu,¶ and Henry P. Fleming (October 2007) “DNA Fingerprinting of Lactic Acid Bacteria in Sauerkraut Fermentations”