How Long Does Fermented Food Last? Full Guide

Fermentation is a method of preserving food that has been used by people since ancient times. As this is a food preservation method, you might be wondering how long fermented food lasts. Does fermented food go bad?

Fermented food can last 3 months or more if kept in a cool and dry area in sealed containers. This timeline can vary based on what type of food has been fermented. It is possible for over-fermentation to occur and spoil the food. 

There is a lot to learn about fermentation before beginning. In this article, you’ll learn all you need to know about the:

• shelf-life of fermented foods
• signs fermented food has gone bad
• how to prevent food spoilage

The Shelf Life of Fermented Foods

The shelf-life of fermented foods varies depending on the type of fermentation and other factors that affect the fermentation process. 

Fermentation is an age-old method to preserve foods that have been used by people for generations. In recent years, fermented foods have also become very popular, mainly due to the health benefits it offers.

To state the entire fermentation process in simple words, it is a process of preserving food by culturing specific strains of yeast or bacteria into the food in a controlled environment. Unwanted and harmful mold, yeast, or bacteria can’t grow in the food, and it will last longer as a result.

There are common ferments around you that you might not notice. For example, yogurt which is fermented milk. Milk will last a week at best after opening it for the first time. On the other hand, yogurt can last at least two weeks before it gets spoiled.

Predicting how long fermented foods will last before spoiling is a challenge. There are simply a lot of variables that control the outcome of fermented foods. If everything is in ideal condition, here are some examples of the shelf life of some fermented foods:

#1: Fermented Alcoholic Beverages

Homemade alcoholic beverages are fermented with a yeast-based culture. Examples:

• beer
• wine
• cider

Typically, they last longer than other fermented foods. The fermentation becomes alcoholic as they age, and bacteria and yeasts can’t survive in an alcoholic environment.

Homemade beers normally have a shelf life of around four months.

Ciders might need to be refrigerated immediately after bottling to slow down the carbonation process so it will last longer. Usually, homemade ciders are at their finest state during the first four weeks after bottling.

The longer a wine ages, the better its taste will be. Always store homemade wine in cold and dark places. It’s best to let the wine age at least one year before drinking. Usually, wines have a shelf life of five years if stored under ideal conditions.

#2: Shelf-Life of Fermented Vegetables

Vegetables become very acidic as they ferment, and most of the harmful and unwanted bacteria can’t survive in an acidic environment. As the ferment ages, the vegetable will become much softer and more acidic. 

Cucumber pickles and sauerkrauts are known for their long fermentation time. And if the fermentation is good and stored at the proper temperature and in a dark place, they can last up to one year before getting spoiled.

NOTE: Wondering what the difference is between fermenting and pickling, and which is better? Read my article to find out!

Pickled vegetables’ shelf life depends on how you want to eat them. As mentioned before, pickled vegetables become softer and more acidic as they age, and also have changed:

• color
• texture
• taste

Most fermented vegetables can last six to twelve months, depending on the:

• vegetable type
• ingredient quality
• storage environment

Unlike sauerkraut, kimchi tastes best within three to five days of fermentation but can be stored for up to one year in the refrigerator.

These ferments can be stored for up to six months in the freezer before going bad:

• hot sauce
• salsa
• chutney

#3: How Long to Keep Miso

Miso is another fermented food that tastes better with age. Good miso is aged for at least one year and should be stored in the refrigerator once it’s opened to prevent it from spoiling. 

#4: Naturally Fermented Drinks

Examples of homemade fermented beverages that have a decent shelf life are:

• water kefir
• kombucha
• Jun

If stored in a refrigerator, they can last up to six months. But as they age, they taste more sour so enjoy them while their taste is great.

Factors That Determine the Shelf Life of Fermented Foods

As mentioned before, there are many factors that directly affect the process of fermentation. Some of them are given below:

#1: Fermentation Temperature is Important

Temperature is the most important factor that influences and has a direct effect on the fermentation process.

If the weather is hot, it will speed up the fermentation and decomposition process. On the other hand, a colder environment slows down the fermentation and decomposition of foods. This is why it is extremely important to store fermented foods in cold and dark places to maximize their shelf life.

#2: Salt Level in The Brine

Another factor that determines how long fermented foods will last is the salt level in the brine. If it is too low, it might speed up the fermentation process, and shorten the shelf life of the ferment.

If the salt concentration in the brine is high, it can significantly slow down the decomposition process.

#3: The Acidity Level Of The Ferment

All types of fermented food become acidic as they ferment. The acid level keeps harmful and unwanted molds and bacteria from growing, helping to preserve the food.

#4: Anaerobic Environment For Fermentation

Yeasts, molds, and bacteria grow rapidly in an oxygen-rich environment. The main point of fermentation is to inhibit the growth of harmful:

• yeasts
• molds
• bacteria  

For good fermentation, keep oxygen away from fermented foods and keep them submerged in the brine solution.

HOT TIP: Airtight jars are best for fermentation.

How to Tell If Fermented Food Is Spoiled

Has your fermented food gone bad or not? It’s easy to identify by observing some common signs, some you can tell just by looking. Here are some common signs of spoiled fermented foods:

#1: Discoloration Of Fermented Food

To identify spoiled fermented food, first carefully visually inspect the color of the food. Older fermented foods might appear a bit cloudy but are still ok.

If you notice anything that is not normal like a bright green cucumber turning black or grey, then there is a good chance it has gone bad.

This type of discoloration indicates that the food became contaminated during the fermentation process, and should not be eaten.

#2: Check for Mold or Yeast Formation

During the entire fermentation period, make sure that the fermenting foods are submerged in the brine and stored in a jar with an airlock like this sold on Amazon. This prevents the fermented foods from coming in contact with oxygen, which can trigger the growth of toxic mold and bacteria in the ferment.

Any mold is a sign that your fermented food is contaminated. Typically, molds are spotted on top of the food or on the lid of the jar, because bacteria can survive on salt brine. 

If you see mold, toss that batch of fermented food away and thoroughly clean and sanitize the jars before reusing them.

Sometimes you might notice a fuzzy white substance on fermented food that can be mistaken for mold, but is actually a yeast formation known as “Kahmâ€. They can be spotted on the surface of fermented foods and are not harmful to human health. 

The Kahm yeast can be scraped off of the surface and the ferment can be eaten as normal. Although, you need to keep an eye on the ferment as it can come back easily.

#3: A Bad Smelling Ferment

Check if the fermented food is bad or not by the smell. Fermented foods go bad mainly because of harmful bacteria, which produce a very bad smell. In some cases, the smell will be so foul that you won’t be able to withstand it.

The harmful bacteria release gases which is the source of the foul smell in your fermented food. If the smell lasts long even after keeping the jar open for a while, the food might be contaminated. 

Over-fermented foods can stink, but it doesn’t mean that they are bad. If you notice that the smell is different than normal, then there is a problem with the food, and throwing it away is a good idea.

#4: Foul or Weird Tasting Ferment

The last sign of bad fermented food is a foul taste. If the taste is somewhat off or is not the usual taste, then there is a good chance that the ferment has spoiled. In this case, it is not a good idea to eat it.

Is it Safe to Eat Spoiled Fermented Food?

It is not safe to eat fermented food that has spoiled. The main reason for eating fermented food is the health benefit it provides. Fermented foods can help improve digestion and boost immunity.

It is not recommended to consume spoiled fermented food since it can cause health issues. Fermented foods go bad mainly due to harmful bacteria growth and when consumed can cause food poisoning.

How to Prevent Fermented Food From Going Bad

Below are some things that you can do to prevent fermented food from going bad:

#1: Properly Clean and Sanitize Fermenting Equipment

It is essential to clean and sanitize the jars thoroughly before starting any sort of fermentation, especially when preparing to brew beer or wine. 

First, wash the jar thoroughly with hot water and dish soap. Use a brush to get rid of any particles inside the jar, then rinse it with tap water. This is enough cleaning to ferment vegetables. 

For brewing alcoholic fermented drinks, some extra cleaning and sanitizing is necessary. Once the jar is cleaned using the method mentioned above, soak it in bleach water. To do that, pour one tablespoon of bleach into a large bowl and fill it with water.

Then simply submerge the jar entirely into the bleach water and soak it for a few minutes. Then, rinse it with tap water. Bleach will kill all the bacteria in the jar. 

#2: Use Good Quality Ingredients

Always use the best quality ingredients. If there is anything wrong with the ingredient like a portion of the vegetable is bad, then cut out the bad portion and get rid of it.

Store-bought vegetables can contain preservatives like chlorine. Supermarkets do this to keep the food fresh for a longer period. Avoid supermarket foods for fermentation, because the preservatives will hinder the growth of good bacteria during fermentation and lead to spoilage.  

This is why you have to be very selective about the ingredients used to ferment. The best way is to buy organic ingredients directly from farms. Also, wash and clean the vegetables thoroughly before fermenting.

#3: Maintain The Right Fermentation Temperature

While fermenting, keep a close eye on the temperature. If it is too warm, it can speed up the fermentation process, and the ferment will be slimy. 

On the other hand, if the temperature is too cool, it can slow down the fermentation process significantly. What usually takes seven days will take more than ten days if the temperature is too low.

The ideal temperature for fermentation is between 65-72 degrees Fahrenheit. During summertime, maintaining this temperature might be a bit tough. Keep your fermentation jar in a cold and dark place, like in the basement at that time. 

#4: Brine Strength is Important

The strength of the brine is also one of the factors that affect the shelf life of fermented foods. The salt brine strength should be such that no harmful bacteria can grow in the jar. Most fermentation recipes recommend a 2-3% brine solution relative to the weight of the ingredients. 

For some vegetables, the required salt concentration for successful fermentation can increase up to 5%. So, whatever recipe you are following for your fermentation, make sure that the salt concentration is within the recommended limit. 

NOTE: Always keep your ingredients submerged under the brine. This will significantly decrease the chance of spoilage.

#5: Avoid Chlorinated Water

Chlorine is used as a cleaning agent that kills almost all types of bacteria strains in water. This is what makes chlorinated water unsuitable for fermentation purposes.

If you use chlorinated water for fermentation, it will kill all the bacteria during the fermentation process, whether good or bad. 

Also, chemically treated water contains strains of bacteria that can withstand chlorine. If this type of water is used, then harmful bacteria will grow during fermentation, and the fermented food will go bad.

This is why you should always use filtered water that is free from any type of chemical or contamination during the entire fermentation process. By doing so, you will be able to create a high-quality brine solution that will be able to keep your fermented food safe for a long time.

Conclusion

Fermentation is an easy way to preserve various types of food. To prevent spoilage, before fermenting make sure to:

• clean and sterilize everything properly
• avoid chlorine-treated water
• maintain a suitable temperature

You might also be interested in:

• What You Need for Fermentation: Essentials & Nice to Haves
• No Salt? Ferment Your Foods Anyway!