What is Food Fermentation? Everything you need to know

What is Food Fermentation? Everything you need to know

What is food fermentation?

Food fermentation is the basic conversion of carbohydrates into alcohols and acids by microbes.

Put another way, fermentation is a type of chemical breakdown that converts carbohydrates to alcohols and acids by microorganisms. 

The majority of the time the microbes responsible for fermentation are yeast or bacteria.  Fermentation results involve effervescence and the release of heat. 

Why is food fermented?

Food is fermented for a number of reasons.  As with most other ancient techniques of preserving food, the main reason for food fermentation is to extend the usability of perishable foods.

Food Fermentation example sauerkraut canned, salt, and cabbaage
Food Fermentation example of sauerkraut. Cabbage is fermented so it can be comused months after harvest.

Fermentation converts biodegradable (or perishable) foods into more stable substances.  This conversion increases the foods stability into a system that is capable of preventing or inhibiting further microbial degradation.  The alcohol or acids act as a natural preservative.

In addition, fermentation is an amazing natural tool makes food more digestible, nutritious and flavorful.  Innovation with fermentation is becoming increasingly popular both with home cooks and within the Food Industry. 

You can use fermentation to make uniquely delicious food or to extend the shelf life of the ingredients.

What food is made from fermentation?

Many everyday foods are made from fermentation including chocolate, coffee, soy sauce, yogurt, cottage cheese, sour cream, fish sauce, beer, wine, liquor, salami and cheese. 

fermented foods include beer and sourdough bread
Beer and sourdough bread are examples of food that are fermented.

My favorite is chocolate.  Cocoa is fermented before it is converted into the chocolate that you love.

What are microbes?

Microbes are microscopic, single-celled organisms.  Even though you cannot see them, they are everywhere. 

National Institutes of Health (NIH) estimate, 90% of cells in the human body are bacterial, fungal or otherwise non-human. 

When you hear the word microbe, you may associate it with negative things such as dirt and disease.  That is common but it is only a small piece of the picture. 

Most microbes are beneficial.  Which is good news since they are abundant in the world.  In addition, fermentation would not be possible without helpful microbes.

food fermentation is possible because of microbes. Microbes are abundant in nature.
Food fermentation is possible because of microbes. Microbes are abundant in nature.

What are the 3 types of fermentation?

There are three main types of fermentation lactic acid, ethyl alcohol and acetic acid fermentations.

  1. Lactic acid fermentation:  This type of fermentation occurs when yeasts and bacteria transform sugars or starches into lactic acid.  Examples include bread, yogurt and sourdough bread.

  2. Ethyl alcohol fermentation: The second type of fermentation happens when pyruvate molecules in sugars or starches are broken down by yeasts into alcohol and carbon dioxide molecules. Examples include beer, wine and cider.

  3. Acetic acid fermentation: This type of fermentation occurs when sugars or starches from grains or fruit are converted into acetic acid. Acetic acid is sour so these products are quite sour.  Examples include vinegar and kombucha.
The 3 types of Food Fermentation

Microbes involved are specialized for each type of fermentation.  For example, yeast cannot be used for acetic acid fermentation and vice versa. 

What are the Benefits of Fermented Foods

Fermented foods have a healthy halo because they are associated with improved health. By consuming fermented foods, you may be adding beneficial bacteria and enzymes to your overall intestinal flora. 

Researchers link fermented foods with health benefits including digestive health and enhancing your immune system. Fermented fruits and vegetables can be an excellent addition for a plant-based diet.

Improves Digestive Health

Numerous studies have linked gut health with fermented foods.  For these reasons, adding fermented foods to your diet may be beneficial if you regularly have gut issues.

An explanation may be the presence of probiotics.  Fermented foods have high levels of probiotic bacteria.  Probiotics produced during fermentation can help balance the friendly bacteria in your gut and may alleviate some digestive problems. 

Immune System Boost

The second benefit is especially relevant in the times of COVID, immune boosting.

The bacteria that live in your gut have a significant impact on your immune system.  Like gut health, research links probiotics from fermentation with immune boosts.  This varies with the product and type of fermentation so more research is needed.

Generally, fermentation makes it easier for you to digest and absorb its nutrients.  Many fermented foods are rich in vitamin C, iron, and zinc.  These vitamins and minerals contribute to a stronger immune system.  Also, fermentation increases the bioavailability of nutrients.  

Some studies have shown that fermented foods may also promote mental health, weight loss heart health. 

Food Fermentation Research in lab for benefits
Research to identify benefits is ongoing for fermented foods.

Conversely, there is conflicting information around health benefits.  More research is needed.

How often should you eat fermented foods?

No set standard or guideline is set yet for how much you should eat.  Everyone is different, so it is up to you.  The American Academy of Nutrition and Dietetics recommends 2 to 3 servings per day.

If you are starting to add fermented foods to your diet, start small and see how your body reacts.  You can increase consumption over time as your gut adjusts.

If you are having stomach discomfort, reduce the amount you are eating. 

As with the fermented products in the store, remember all foods add calories to your diet.  Make adjustments for this increase in calories.

Can you eat too much?

As with anything in life, balance is everything.  You can’t eat too much fermented products.  If you only consume things that are fermented, you may end up causing damage to your digestive system due to the high acid and alcohol levels.  Eat everything in moderation.

Are fermented food products from the grocery store healthy?

When you are purchasing already fermented food products, keep in mind is that not all fermented foods are inherently healthy.  

Always read the ingredients nutrition panel. Also, make sure you buy from a manufacturer that you trust.  Many fermented products have added sugars and other added ingredients. They can also be high in calories.

Another thing, some products are sterilized for food safety reasons.  If you are looking for the microbe benefits make sure the product is not sterile.  Producers have to list the live and active cultures.  

Grocery store showing packaged food
Keep in mind is that not all fermented foods are inherently healthy. Look at the ingredients and nutrition label.

What are the dangers of Fermented Food?

As with everything in life, there are risks associated with fermented foods. 

Gas and Bloating

A common side effect of fermented foods can be a temporary increase in gas and bloating.  These side effects will usually disappear within a couple of hours and are not a sign that the fermentation was incorrectly processed.

If you are starting to add fermented foods to your diet, start small and see how your body reacts.  You can increase consumption over time as your gut adjusts.

Foodborne Illness

The second is the risk of foodborne illness mainly comes from home fermented products.  Clostridium botulinum is most commonly found in home-canned food products

Make sure you do diligence on the process and tools needed for the type of product you are fermenting before you ferment.  If you make these products correctly then you should be safe eating them.

Final Thoughts

Food fermentation is the basic conversion of carbohydrates into alcohols and acids by microbes.

Common fermented foods include chocolate, coffee, kimchi, sauerkraut, cheese, kombucha and yogurt.  

These foods are associated with health benefits like immune system boosts and increased digestive health. 

Fermentation is used for a number of reasons such as preservation, sensory and unique flavors. 

What is your favorite fermented food?


Turnbaugh PJ, Ley RE, Hamady M, Fraser-Liggett CM, Knight R, Gordon JI.  Human Genome Project.
Nature 449p804-10(2007 Oct 18). https://pubmed.ncbi.nlm.nih.gov/17943116/. Retrieved 23 August 2020.

Aramouni, Fadi and Kathryn Deschenes.  Methods for Developing New Food Products.  Lancaster PA.  DEStech Publications, Inc.  2015.

A meta-analysis of probiotic efficacy for gastrointestinal diseases.  https://pubmed.ncbi.nlm.nih.gov/22529959/.  Retrieved 23 August 2020.

Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723656/. Retrieved 23 August 2020.

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