Fermentation is one of the oldest methods of food processing.
Lacto-fermentation is a specific type of fermentation that uses lactic-acid-producing bacteria to preserve foods.
While fermentation was traditionally used to increase shelf life, recent research has highlighted several health benefits of eating lacto-fermented foods.
This article explains everything you need to know about lacto-fermentation.
What is lacto-fermentation?
Food fermentation is the process whereby bacteria, yeasts, mold, or fungi break down carbs — such as starch and sugar — into acids, gas, or alcohol. The process results in a fermented food product with a desirable flavor, aroma, or texture (
There are different types of fermentation: wine is produced by alcoholic fermentation using yeast, vinegar is fermented with acetic-acid-producing bacteria, and soybeans are fermented by mold into tempeh (2).
The term “|acto” refers to lactic acid, which is a type of acid that’s produced upon the breakdown of sugar in an oxygen-free environment. It was first identified in milk, which contains the sugar lactose, hence the name lactic acid.
Lacto-fermentation uses lactic-acid-producing bacteria (primarily from the Lactobacillus genus), as well as some yeasts. These bacteria break down the sugars in food to form lactic acid and sometimes alcohol or carbon dioxide (
In addition, a large number of less well-known, traditional lacto-fermented foods are produced all over the world. These include Turkish shalgam, which is a red carrot and turnip juice, and Ethiopian injera, a sourdough flatbread (3,
Lacto-fermentation is the process by which bacteria break down the sugars in foods and form lactic acid. Lacto-fermented foods include yogurt, sauerkraut, kimchi, and pickles.
How does it work?
Populations of lactic acid bacteria are found throughout nature, including in animals and humans. Those found in milk and on fruits, grains, vegetables, and meat can be used for fermentation.
Alternatively, special cultures can be bred and added to foods to start the fermentation process. This is useful for foods that don’t have naturally occurring populations, enabling a particular flavor or aroma or to ensure food quality and safety (3,
The simplest method of lacto-fermentation is to submerge a food that naturally contains lactic acid bacteria, such as cabbage or cucumber, into a brine of water and salt.
Fermented milk, yogurt, and sourdough may also ferment on their own, but often a starter culture is used to ensure safety and consistency of flavor.
A sealed container, such as a glass jar, ceramic crock, or food-grade plastic container, is typically used to limit oxygen exposure. Some foods like sauerkraut are stored in large barrels and weighted down to keep the vegetable submerged in the salty brine.
As bacteria break down sugar, lactic acid and carbon dioxide are formed, removing oxygen and making the food more acidic. This encourages the growth of even more lactic acid bacteria and prevents the growth of other microorganisms (3).
The time it takes to ferment ranges from days to months. Afterward, the fermented food is usually stored in a cool place to slow any further fermentation and prevent spoilage.
During lacto-fermentation, lactic acid bacteria break down carbs into lactic acid and carbon dioxide. This creates an acidic, low-oxygen environment that encourages the growth of good bacteria and prevents the growth of other microorganisms.
Why is it used?
Fermentation has been used to preserve food for thousands of years, as it’s very simple, inexpensive, and effective (
Fermented foods can be stored for varying lengths, depending on the food, temperature, container, and any further processing. Milk keeps for a few days to weeks, refrigerated yogurt for up to a month, and fermented vegetables for 4–6 months or longer.
Some fermented foods are pasteurized after fermentation, which kills all live bacteria and allows for a longer storage time. However, these foods don’t provide the health benefits of live bacteria cultures.
In addition to preservation, fermentation makes food easier to digest, reduces or eliminates the need for cooking, extends shelf life, reduces food waste, and adds distinctive flavors, textures, and aromas (2, 3,
Lacto-fermentation has traditionally been used to preserve food by preventing the growth of harmful microorganisms. This extends the shelf life of foods and reduces food wastage, all while adding flavor, texture, and aroma.
How’s it different than canning?
Fermented and canned products may look similar, but they are quite different.
Canning uses heat to sterilize food and eliminate or reduce the growth of harmful organisms. As the food is sealed in a can or jar, no harmful organisms or air can get inside, and the food can be stored for a very long period (10).
On the other hand, lacto-fermentation utilizes live bacteria to prevent the growth of harmful organisms. Fermented products may still undergo some heat processing, as in the case of pasteurized fermented milks, but they are not heated to the same extent (11).
Canned foods tend to have a longer shelf life than fermented foods, but they’re also more difficult to make, especially at home. Canning requires specialized sterilization equipment, whereas basic fermentation requires only a container, water, and sometimes salt.
The flavors, textures, and aromas of fermented and canned foods are also very different. Canned food is cooked, soft, and may contain added sugar or salt. Lacto-fermented foods are typically not cooked, have a distinct aroma, and taste acidic and sometimes salty.
Canning uses heat to cook food and kill harmful organisms, whereas lacto-fermentation uses good bacteria to prevent the growth of harmful organisms.
Health benefits of lacto-fermented foods
Increasing evidence suggests that fermented foods have health benefits beyond those offered by their original ingredients. This is mainly attributable to the compounds produced by lactic acid bacteria (
For example, during milk fermentation, bacteria produce a blood-pressure-lowering compound known as angiotensin-converting-enzyme inhibitor (ACE inhibitor). Thus, fermented milk may help treat high blood pressure (
Another example is kimchi, the traditional Korean fermented cabbage. It contains a variety of amino acids and other bioactive compounds that have been found to reduce heart disease and help fight inflammation, some cancers, infections, and obesity (
Furthermore, fermented foods like dairy, sauerkraut, and olives are rich sources of living bacteria. These bacteria may contribute to health in a manner similar to that of probiotics, supporting gut and immune function (
Other potential benefits of lacto-fermented foods include:
- Increased nutrient availability. Fermentation increases the availability of nutrients in food. For example, iron is more readily absorbed from fermented vegetables than non-fermented ones (
- Reduced inflammation. Fermented foods can lower counts of inflammatory molecules, increase antioxidant activity, and improve the protective barrier of your gut (
- Improved heart health. Yogurt and fermented milk have been found to modestly reduce blood pressure and cholesterol levels (
- Immune function support. Some strains of lactic acid bacteria, such as those in Kyoto and Sunki pickles, have been shown to exhibit immune-boosting, antiviral, and antiallergenic effects (
29, 30, 31).
- Cancer-fighting properties. Fermented milk is associated with a lower risk of some cancers, and some types have even been shown to kill and inhibit the growth of cancer cells in test-tube and animal studies (
32, 33, 34).
- Better blood sugar control: Many fermented foods, such as kimchi, fermented milk, and yogurt, have been found to improve insulin sensitivity and blood sugar control (
35, 36, 37).
- Weight control. Eating yogurt, fermented milk, and kimchi is associated with weight loss and better weight control (
38, 39, 40).
- Improved brain function. Fermented milk products have been shown to improve cognitive function in adults and people with Alzheimer’s disease, although more research is needed (
- Reduced symptoms of lactose intolerance. As lactose is broken down during the fermentation process, people with lactose intolerance can sometimes tolerate fermented milk products like yogurt and cheese (
Lacto-fermentation may increase the nutrient availability of foods, improve heart and brain health, and have anti-inflammatory, cancer-fighting, immune-boosting, antidiabetic, and anti-obesity benefits.
The bottom line
Lacto-fermentation uses lactic acid bacteria to simply and effectively preserve food.
Lacto-fermented foods may boost heart and brain health and offer anti-inflammatory, cancer-fighting, immune-boosting, antidiabetic, and anti-obesity benefits.
Many fermented foods taste great and can be easily incorporated into your diet. These include refreshing drinks like buttermilk, snacks, such as yogurt or olives, and side dishes like sauerkraut and kimchi.