Fermented foods: Which foods contain live cultures?

Sauerkraut, yogurt, kimchi, kefir, or sourdough – we encounter fermented foods more often than one might initially think. Microorganisms such as bacteria or yeasts play a decisive role in their production. However, an important distinction is frequently overlooked: Not every fermented food still contains live cultures at the time of consumption. And fermented does not automatically mean probiotic or postbiotic.

This overview shows which foods can actually contain live microorganisms, how to identify them, and what distinguishes fermented, probiotic, prebiotic, and postbiotic foods from one another.

What are fermented foods?

During fermentation, foods are altered with the help of microorganisms and their metabolic processes. Bacteria, yeasts, or other microorganisms convert components of the original food in the process.

For example, sugar can be converted into lactic acid or other metabolic products. This changes the taste, consistency, and shelf life of the food. It is precisely these processes that humans have been using for centuries to produce a wide variety of foods.

Typical examples include:

• Yogurt and kefir
• Sauerkraut
• Kimchi
• Sourdough
• Kombucha
• Miso
• Tempeh
• Certain types of cheese

It is important, however, to note: The microorganisms required for fermentation do not necessarily have to be alive in the finished food. Some products are heated, pasteurized, baked, or filtered after fermentation. This can reduce or completely inactivate the microorganisms present during fermentation.

Fermented foods: List with examples

Whether a fermented food contains live cultures when consumed depends heavily on its production and processing.

Food	Fermented?	Live cultures possible at consumption?
Plain yogurt	Yes	Often yes
Kefir	Yes	Often yes
Sauerkraut	Yes	Yes, if not subsequently heated
Kimchi	Yes	Often yes
Kombucha	Yes	Depends on product and processing
Sourdough bread	Yes	Generally no
Miso	Yes	Depends on processing
Tempeh	Yes	Yes before heating, significantly reduced after cooking
Cheese	Depends on variety	Depends on production
Pickles	Not automatically	Only for truly fermented varieties

This overview already shows: The term “fermented” initially describes the production – not whether live microorganisms are still present in the finished product.

Which fermented foods contain live cultures?

Live microorganisms are found particularly often in fermented foods that are no longer heavily heated or pasteurized after they are produced.

These can include, for example, refrigerated, non-pasteurized sauerkraut, kimchi, some yogurts, kefir, or certain kombucha products.

But even here, it cannot be said across the board which quantity or which specific microorganisms a food contains at the time of consumption. Production, storage, temperature, and shelf life can influence the composition and number of microorganisms.

Therefore, with packaged products, it is worth taking a close look at the packaging and the manufacturer’s information.

Fermented does not automatically mean probiotic

In everyday language, "fermented" and "probiotic" are often treated as the same thing. Scientifically, however, they are different terms.

A fermented food is created through the targeted growth of microorganisms and the resulting transformation of its components.

For microorganisms to be scientifically classified as probiotics, specific requirements apply. Among other things, they must be defined live microorganisms for which a health benefit has been proven at a certain quantity.

The microorganisms in traditionally fermented sauerkraut or kimchi, by contrast, are often neither present in a standardized amount nor defined down to specific strains.

Therefore:

A food can contain live microorganisms without automatically being considered a probiotic food.

The term "probiotic" should therefore not be used as a blanket term for all fermented foods or products with live cultures.

Probiotic foods: what is meant by that?

The term "probiotic" does not simply describe every food that has been produced by microorganisms or contains live cultures. Instead, it refers to defined live microorganisms for which a health benefit has been proven under certain conditions.

Some products are specifically made with certain cultures and labeled accordingly. With traditionally fermented foods, however, it is often not clearly known which microorganisms are present in what quantity at the time of consumption.

Yogurt

In the production of yogurt, lactic acid bacteria ensure that milk sugar is converted into lactic acid. This creates the typical consistency and the slightly sour taste.

Many yogurts still contain live yogurt cultures when consumed. However, it does not automatically follow that every yogurt product can be classified as probiotic.

Kefir

Kefir is also created through fermentation. Various bacteria and yeasts work together in this process. Traditionally produced kefir can contain a multitude of live microorganisms when consumed.

Which microorganisms are actually present depends, among other things, on the cultures used, the production, and the storage.

Kimchi

Kimchi is a traditional Korean fermented vegetable dish, often made from Napa cabbage, radish, spices, and salt. During fermentation, lactic acid bacteria in particular multiply.

If the kimchi is not pasteurized afterwards, live microorganisms may remain in the ready-to-eat product. However, this property alone does not automatically make kimchi a probiotic food.

Sauerkraut

For traditional sauerkraut, finely shredded cabbage is fermented with the help of lactic acid bacteria.

Fresh or refrigerated, non-pasteurized sauerkraut can contain live microorganisms. Sauerkraut from cans or jars, however, is often heated to give it a longer shelf life. This can reduce the live cultures.

Kombucha

Kombucha is created through the fermentation of sweetened tea with the help of a symbiotic colony of bacteria and yeast.

Unpasteurized kombucha can therefore contain live microorganisms. Here, too, the actual composition depends heavily on the production method, the product, and storage.

What are postbiotic foods?

In addition to fermented, probiotic, and prebiotic foods, the term postbiotic is also increasingly being used.

Simply put, postbiotics are inactivated microorganisms and components or metabolic products of microorganisms that can provide a health benefit. Unlike probiotics, they do not need to be alive.

These can include, for example:

• components of bacterial cells
• inactivated microorganisms
• enzymes
• organic acids
• certain metabolic products
• other substances that are created during fermentation

However, the term is not synonymous with "fermented." A fermented food can contain postbiotic components, but it does not automatically count as a postbiotic product. For that, the components contained must be more precisely characterized and a health benefit must be proven under certain conditions.

Even a heated fermented food can still contain metabolic products or components of the originally involved microorganisms. While the heating process may mean the microorganisms are no longer alive, the substances created during fermentation can sometimes remain.

Which fermented foods no longer contain live cultures?

Even foods without live microorganisms can clearly be fermented foods.

This sounds contradictory at first, but it is easy to explain: What is decisive for the label "fermented" is the production process.

If the microorganisms are subsequently inactivated by heat or other processing steps, the food remains a product of fermentation.

A good example of this is sourdough bread.

Is sourdough probiotic or postbiotic?

For sourdough, lactic acid bacteria and yeasts work together. Among other things, they ensure that the dough rises and develops its typical aroma.

However, baking temperatures reach levels that most of these microorganisms do not survive.

Sourdough bread is therefore a fermented food, but generally no longer contains any live cultures after baking.

During fermentation, however, various metabolic products are formed that contribute to the taste, smell, and properties of the bread. Whether a finished sourdough bread can therefore be described as a postbiotic food cannot be said in general terms. For this, the contained components and a possible health benefit would need to be investigated and defined more precisely.

Similar things apply to other fermented products that are strongly heated, roasted, pasteurized, or filtered after fermentation.

What are prebiotic foods?

In addition to fermented, probiotic, and postbiotic foods, another term often appears: prebiotic foods.

Prebiotic and probiotic do not mean the same thing.

Prebiotics are specific substances that are utilized by microorganisms and can thereby provide health benefits. These are often certain carbohydrates that are not or only partially digestible.

Foods that contain corresponding dietary fibers include, for example:

• Chicory
• Jerusalem artichoke
• Onions
• Garlic
• Leeks
• Certain whole grain products
• Legumes

A food does not have to be fermented for this, nor does it necessarily contain live microorganisms.

Fermented, probiotic, prebiotic, or postbiotic: What is the difference?

The terms can be simplified and distinguished as follows:

• Fermented:
  The food was produced or modified using microorganisms and their metabolic processes.
• With live cultures:
  The food still contains live microorganisms at the time of consumption.
• Probiotic:
  Certain live microorganisms meet defined scientific requirements, and a health benefit has been proven for them in sufficient quantities.
• Prebiotic:
  Certain components of a food are utilized by microorganisms and can thereby provide a health benefit.
• Postbiotic:
  Inactivated microorganisms or components or metabolic products of microorganisms can provide a health benefit under certain conditions. The contained microorganisms do not have to be alive.

This distinction is particularly helpful for consumers: for example, a sourdough bread is fermented but normally contains no live cultures after baking. An unpasteurized kimchi, on the other hand, can be fermented and contain live microorganisms simultaneously. However, these are not automatically classified as probiotics. A heated fermented food can in turn contain certain metabolic products or components of microorganisms without having any live cultures.

Are fermented foods healthy?

Fermented foods are increasingly being studied scientifically. Researchers are interested, among other things, in how the fermentation process affects the composition of a food and the microorganisms and metabolic products it contains.

Fermentation can, for example, change the shelf life, taste, and availability of certain nutrients. At the same time, fermented foods can contain live microorganisms, inactivated cell components, as well as various metabolic products of fermentation.

What significance these components have for health depends on the specific food, the substances contained, the amount consumed, and other individual factors.

Nevertheless, the blanket statement "fermented foods are healthy" would be too simplistic.

The specific food and its composition are always the deciding factors.

Natural yogurt, kimchi, sauerkraut, kombucha, or sourdough bread differ considerably in terms of ingredients, nutritional values, and processing.

Can fermented foods also be unhealthy?

Fermentation does not automatically make a food healthy—but it also doesn't automatically make it unhealthy.

When choosing, it is therefore worth looking at the product as a whole.

• Salt:
  Products like sauerkraut, kimchi, miso, or certain types of cheese can contain relatively high amounts of salt.
• Sugar:
  For kombucha and other fermented drinks, it is worth checking the sugar content of the finished product.
• Processing:
  Pasteurization or intense heating can mean that the microorganisms originally contained are no longer alive. At the same time, certain metabolic products or cell components can be partially preserved.
• Individual tolerance:
  Not every food is equally well tolerated by everyone. Those who are not used to certain foods can, for example, start with smaller amounts first.

A single fermented food should therefore not be evaluated in isolation. What matters is how it fits into your overall diet.

How can you tell if a fermented food contains live cultures?

With supermarket products, it is not always apparent at first glance whether live microorganisms are still present.

A few clues can help when selecting them:

• Pay attention to processing:
  Terms like “pasteurized” or “heat-treated” suggest that many of the original microorganisms have been inactivated by the manufacturing process.
• Check for refrigeration:
  Products with live cultures are often sold in the refrigerated section. However, a requirement for refrigeration alone is not definitive proof.
• Read the ingredients and product information:
  Some manufacturers list the cultures or microorganisms used on the packaging.
• Don't rely solely on the term “fermented”:
  This describes the manufacturing process, not the quantity of live microorganisms or postbiotic components in the finished product.
• Evaluate “postbiotic” claims critically:
  The term “postbiotic” should not be applied blanketly to every heated or fermented food. Concrete information regarding the components contained and the scientific basis is more informative.

How can fermented foods be integrated into everyday life?

Fermented foods do not have to be exotic specialty items. Many can be easily integrated into normal meals.

For breakfast, for example, natural yogurt or kefir are options. Unpasteurized sauerkraut or kimchi can be used as a small side dish. Sourdough bread is a suitable alternative to other types of bread, even if it no longer contains live cultures after baking.

Those who rarely eat fermented foods do not need to change their diet completely all at once. Trying different foods and paying attention to individual tolerance is usually the easier path.

Frequently asked questions about fermented foods

Which foods are fermented?

Some of the best-known fermented foods include yogurt, kefir, sauerkraut, kimchi, sourdough bread, kombucha, miso, tempeh, and certain types of cheese. Whether they still contain live microorganisms when consumed depends on their further processing.

Which fermented foods contain live cultures?

Non-pasteurized products such as certain yogurts, kefir, fresh sauerkraut, kimchi, or kombucha may contain live microorganisms. However, the actual quantity and composition depend on the specific product.

Is every fermented food probiotic?

No. A fermented food does not automatically meet the scientific definition of a probiotic. For that to be the case, among other things, defined microorganisms must be present in a specific quantity and a health benefit must be scientifically proven.

What are postbiotic foods?

Postbiotic foods contain inactivated microorganisms or components, i.e., metabolic products of microorganisms, that can provide health benefits under certain conditions. The microorganisms contained do not necessarily need to be alive.

Is sourdough probiotic?

Sourdough is fermented with the help of live microorganisms. However, these are largely inactivated during baking by the high temperatures. Sourdough bread is therefore fermented, but generally does not contain live cultures when eaten.

Whether certain metabolic products created during fermentation remain depends on production and processing. However, it cannot automatically be inferred from this that every sourdough bread is postbiotic.

Does sauerkraut contain live cultures?

That depends on the processing. Raw or unpasteurized sauerkraut can contain live microorganisms. If sauerkraut is heated or pasteurized after fermentation, however, these are significantly reduced or inactivated.

Is kombucha probiotic?

Kombucha can contain live bacteria and yeasts. However, this does not automatically mean that these microorganisms meet the scientific criteria for probiotics.

Can a heated fermented food contain postbiotic components?

That is generally possible. During fermentation, various metabolic products and cell components are created, which may partially remain after subsequent heating. Whether a specific product can be described as postbiotic, however, depends on its exact composition and scientific assessment.

What is the difference between probiotic, prebiotic, and postbiotic foods?

Probiotics are defined live microorganisms that provide a proven health benefit in sufficient quantities. Prebiotics are substances that are used by microorganisms and can thereby provide a health benefit. Postbiotics are inactivated microorganisms or components, i.e., metabolic products of microorganisms, that can provide a health benefit under certain conditions.

Can you eat fermented foods every day?

Fermented foods can be part of a varied diet. What amount is reasonable, however, depends on the respective food, its composition, and individual tolerance. There is no generally applicable daily amount for fermented foods.

Conclusion: Fermented does not mean the same thing as probiotic or postbiotic

Yogurt, sauerkraut, kimchi, kefir, kombucha, or sourdough all have one thing in common: microorganisms play a decisive role in their production.

Whether these microorganisms are still alive at the time of consumption, however, is a different question. Likewise, it cannot be automatically inferred from the fermentation process whether a product possesses probiotic or postbiotic properties.

Fermented does not automatically mean “with live cultures,” “probiotic,” or “postbiotic.”

Anyone looking specifically for foods with live cultures should therefore pay closer attention to their manufacturing and processing. Non-pasteurized or non-subsequently heated products can contain live microorganisms, while these are largely inactivated, for example, during the baking of sourdough bread.

Postbiotic components can play a role even when microorganisms are no longer alive. However, the term should only be used if the corresponding components and a potential health benefit have been sufficiently characterized and scientifically evaluated.

It is precisely these differences that make fermented foods so diverse – from centuries-old production methods to modern products that focus on living microorganisms, prebiotic substances, or postbiotic components.