What Is Fermented Food?
Fermented foods are found in many cuisines around the world.
Yogurt, kimchi, sauerkraut, miso, tempeh, and some types of pickles are examples of foods that may be made through fermentation.
But what exactly does fermentation mean?
Fermentation is a process in which microorganisms such as bacteria or yeast transform components of food.
The process can change a food’s:
- Flavor
- Texture
- Aroma
- Acidity
- Shelf life
Fermentation has been used in food preparation for thousands of years.
What Is Fermentation?
Fermentation is a natural or controlled process involving microorganisms.
Depending on the food, microorganisms can convert carbohydrates such as sugars into different compounds.
For example, fermentation can produce:
- Lactic acid
- Alcohol
- Carbon dioxide
The exact process depends on the food and the microorganisms involved.
What Foods Are Fermented?
Many familiar foods can be fermented.
Examples include:
- Yogurt
- Kimchi
- Sauerkraut
- Miso
- Tempeh
- Kefir
- Kombucha
- Some cheeses
- Fermented soy products
- Some traditional pickled vegetables
Different countries and cultures have their own fermented foods.
Is Yogurt a Fermented Food?
Yes.
Yogurt is produced by fermenting milk with specific bacterial cultures.
During fermentation, bacteria convert some of the lactose in milk into lactic acid.
This gives yogurt its characteristic:
- Tangy flavor
- Thicker texture
- Acidity
Different yogurt products can contain different cultures and ingredients, so checking the product label can still be useful.
Is Kimchi a Fermented Food?
Traditional kimchi is made by fermenting vegetables, commonly cabbage and radish, with seasonings.
The fermentation process contributes to its distinctive:
- Sourness
- Aroma
- Flavor
- Texture
Kimchi recipes vary considerably, so products can differ in ingredients and sodium content.
Is Sauerkraut Fermented?
Traditional sauerkraut is fermented cabbage.
Cabbage is combined with salt and allowed to undergo fermentation.
The result is a sour and slightly crunchy food that is commonly used as a side dish or condiment.
However, not every product labeled as sauerkraut is necessarily fermented in the same way, so preparation methods can vary.
Is Miso Fermented?
Yes.
Miso is a traditional Japanese food made by fermenting ingredients such as soybeans, grains, salt, and koji.
It is commonly used to add a savory, salty flavor to:
- Soups
- Sauces
- Marinades
- Dressings
Because miso can contain significant sodium, it is useful to consider how much is used in a meal.
Is Tempeh Fermented?
Yes.
Tempeh is traditionally made from fermented soybeans.
The fermentation binds the soybeans into a firm cake-like texture.
It can be:
- Fried
- Baked
- Steamed
- Stir-fried
Tempeh is commonly used as a protein-rich ingredient in many meals.
Is Kombucha a Fermented Food?
Yes.
Kombucha is a fermented tea beverage.
It is typically made by fermenting sweetened tea with a culture of microorganisms.
The fermentation process produces its characteristic tangy flavor.
Commercial kombucha products can vary in sugar content, so checking the label can be useful.
Are Pickles Always Fermented?
No.
This is an important distinction.
Some pickles are made through fermentation.
Others are produced by placing vegetables in vinegar.
These are different processes.
So a food being called “pickled” does not automatically mean that it is fermented.
What Is the Difference Between Fermented and Pickled Foods?
Fermentation relies on microorganisms to transform the food.
Vinegar pickling uses an acidic vinegar solution to preserve and flavor the food.
Some foods can be both fermented and pickled, depending on how they are prepared.
The words are therefore not interchangeable.
Are All Fermented Foods Probiotic?
No.
This is one of the most common misunderstandings about fermented foods.
A fermented food may contain microorganisms, but that does not automatically mean it is a probiotic food.
For a microorganism to be considered a probiotic, it needs to meet specific scientific criteria, including providing a demonstrated health benefit when consumed in an appropriate amount.
So:
Fermented does not automatically mean probiotic.
What Does “Live Cultures” Mean?
Some fermented foods contain live microorganisms at the time they are consumed.
For example, some yogurt products contain live cultures.
However, processing methods such as heating can affect whether live microorganisms remain in a product.
If this matters to you, check the product label for information about live or active cultures.
Does Fermentation Change the Flavor of Food?
Yes.
Fermentation can create flavors that are:
- Sour
- Tangy
- Savory
- Complex
- Slightly sweet
The exact flavor depends on the ingredients and fermentation process.
This is one reason fermented foods are important in many traditional cuisines.
Does Fermentation Change the Texture?
It can.
Fermentation may make food:
- Softer
- Firmer
- Creamier
- More tender
- More complex in texture
For example, yogurt has a different texture from milk, while tempeh has a firm structure created during fermentation.
Can Fermentation Help Preserve Food?
Historically, yes.
Fermentation has been used as one way to help preserve food.
The microorganisms involved can produce acids or other substances that change the food environment.
This can make it more difficult for certain unwanted microorganisms to grow.
Modern food production also uses refrigeration, packaging, pasteurization, and other preservation methods.
Does Fermentation Make Food Last Forever?
No.
Fermented foods can still spoil.
Their storage requirements depend on the specific product and how it was made.
Always follow:
- Storage instructions
- Refrigeration requirements
- Use-by or best-before dates
- Manufacturer instructions
Do not assume that fermentation makes a food permanently safe.
Do Fermented Foods Need to Be Refrigerated?
Many commercially produced fermented foods require refrigeration.
Examples can include:
- Yogurt
- Kimchi
- Some sauerkraut
- Some fermented vegetables
Follow the instructions on the package.
Traditional or homemade fermented foods can have different requirements depending on how they were prepared.
Can You Make Fermented Foods at Home?
Some fermented foods can be made at home.
Examples include:
- Yogurt
- Sauerkraut
- Fermented vegetables
- Some sourdough products
However, fermentation requires appropriate ingredients, equipment, temperature, time, and hygiene.
Improperly prepared fermented foods can present food-safety risks.
If you are new to fermentation, use a reliable food-safety-tested recipe and follow the instructions carefully.
What Should You Look for When Buying Fermented Foods?
Start with the product label.
Depending on the food, you may want to compare:
- Ingredients
- Sodium
- Added sugars
- Serving size
- Storage instructions
- Whether live cultures are mentioned
There is no need to assume that every fermented product is automatically a better choice.
Are Fermented Foods Healthy?
Fermented foods can be part of a varied eating pattern.
Different fermented foods provide different nutrients and ingredients.
For example:
- Yogurt provides nutrients found in dairy
- Tempeh provides protein
- Fermented vegetables can add vegetables to a meal
- Miso can add flavor to soups and sauces
The nutritional value depends on the specific food.
Do Fermented Foods Improve Digestion?
Some fermented foods contain microorganisms or compounds that may interact with the digestive system.
However, the effects depend on the specific food, microorganisms, amount consumed, and individual circumstances.
It is better not to treat fermented foods as a guaranteed solution for digestive problems.
They can simply be one type of food included in a varied diet.
How Can You Add Fermented Foods to Meals?
You do not need to eat large amounts.
Try small additions such as:
Yogurt with breakfast.
Kimchi alongside rice.
Miso in soup.
Tempeh in a stir-fry.
Sauerkraut as a side dish.
Choose foods that fit your normal meals.
Can Fermented Foods Be Used as Condiments?
Yes.
Some fermented foods work especially well as flavor ingredients.
Examples include:
- Kimchi
- Miso
- Sauerkraut
- Fermented sauces
Because some of these foods can be salty, a small amount may be enough to add flavor.
Do You Need to Eat Fermented Foods Every Day?
No.
There is no requirement to eat fermented foods every day.
They can be included as part of an overall varied eating pattern.
You can choose them based on:
- Taste
- Availability
- Culture
- Budget
- Personal preference
How Many Fermented Foods Should You Eat?
There is no universal number that everyone needs.
Instead of focusing on a specific amount, consider variety across your overall diet.
A small serving of yogurt, for example, is very different from a serving of kimchi or miso.
The appropriate amount depends on the food and the rest of your meals.
Are Fermented Foods Suitable for Everyone?
Most people can include fermented foods as part of a normal diet.
However, individual dietary needs and food allergies or intolerances can vary.
Some fermented foods may also contain:
- Dairy
- Soy
- Gluten-containing grains
- High amounts of sodium
- Added sugar
Check ingredients and nutrition information if you need to avoid specific foods.
What Are Some Common Fermented Foods Around the World?
Fermentation is used in many food traditions.
Examples include:
Japan: Miso, natto
Korea: Kimchi
Germany: Sauerkraut
Indonesia: Tempeh
Many regions: Yogurt, cheese, fermented vegetables, bread, and other fermented foods
The exact ingredients and methods can vary greatly.
A Simple Way to Start Eating Fermented Foods
If you rarely eat fermented foods, start with something familiar.
For example:
Option 1
Yogurt with fruit.
Option 2
A small serving of kimchi with rice.
Option 3
Tempeh in a stir-fry.
Option 4
Miso soup with a meal.
There is no need to add several fermented foods at once.
The Simple Takeaway
Fermentation is an important food-making process used across many cultures.
Remember:
- Fermentation uses microorganisms to transform food.
- Yogurt, kimchi, miso, tempeh, and sauerkraut are common examples.
- Not all pickled foods are fermented.
- Not all fermented foods are probiotics.
- Fermentation can change flavor, texture, and acidity.
- Fermented foods can still spoil and may require refrigeration.
- Check labels for sodium, added sugars, ingredients, and storage instructions.
- Different fermented foods have different nutritional profiles.
- You do not need to eat fermented foods every day.
- They can simply be one part of a varied eating pattern.
Fermented foods are not a magic category of food.
They are simply an interesting and useful part of the world’s food traditions.
Sources & Further Reading
Harvard T.H. Chan School of Public Health — The Nutrition Source
General information about fermented foods and their role in eating patterns.
U.S. Food and Drug Administration
General food safety and food-label information.
U.S. Department of Agriculture
General food and food-safety guidance.