The process of fermenting foods has been around for over 8,000 years. The first fermented foods and beverages included bread, beer, and wine. Recently, lacto-fermented foods and beverages have become trendy as healthy dietary supplements, and many people have started making ferments at home.
Lacto-fermentation, often referred to as lactic acid fermentation or simply fermentation, is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. Types of food that have been fermented throughout history include beans, grain, vegetables, fruits, dairy, honey, fish, meat, and tea-based beverages. Some of the more familiar fermented foods are sauerkraut (fermented cabbage), yogurt (fermented milk) and soy sauce made from fermented soybeans. Some of the recently popular fermented foods include kimchi, made from cabbage, radishes, cucumbers, ginger, or other vegetables; kefir, which is a drink made from milk; and kombucha, which is a fermented tea. (1)
Why consume fermented foods? Historically, humans fermented foods as a means of preservation, but today, researchers are beginning to demonstrate that fermented foods have positive results for nutrition and gut health. Fermented foods contain living microorganisms that are similar to strains used as probiotics. Studies have indicated that the consumption of fermented foods has positive benefits for brain activity, type II diabetes, weight management, and heart health. (2)
If you buy fermented foods (such as sauerkraut) at a store, it is likely pasteurized. This process is used to kill harmful bacteria, but it also kills good bacteria and probiotics. Therefore, to obtain health benefits, one must either buy raw (unpasteurized) food or make your own.
You may be wondering about food safety when fermenting. Obtain instructions from credible sources, follow the recipe instructions, and use your nose. If the food goes bad, it won’t smell like pickles or vinegar. It will smell rotten. Credible sources include the university extensions and eperienced experts who have written books or teach courses on the topic. The following passage is from Kirsten K. Shockey and Christopher Shockey, authors of the books Fermented Vegetables: Creative Recipes for Fermenting 64 Vegetables & Herbs in Krauts, Kimchis, Brined Pickles, Chutneys, Relishes & Pastes and the book Fiery Ferments:
"Don't be daunted by fermentation. The worst that can happen is that you have a failed batch. You won't kill your family (cliché alert), but if we had a nickel for every time somebody came to us and said, “I want to do this, but I am afraid I will kill my family,” we would be quite wealthy. After all, for a society that has grown up with germ theory and refrigeration, there is nothing intuitive about letting food sit on your counter for a few days or weeks, possibly having to remove a layer of yeast, and then digging in." (3)
Fermentation advocate and USDA microbiologist Fred Breidt is quoted as saying that, as far as he knows, nobody has died from eating properly fermented vegetables – the operative word being properly, because this is where things can go south. The good news is that if they do, you will know. (3)
Popular Fermented Beverages and Foods
Kombucha is a fermented sweet tea. The fermentation process converts and consumes the sugars and tea, resulting in a beverage that tastes slightly sour or vinegary. Often a second fermentation is conducted with fruit or other flavorings in a sealed container, which allows the drink to become carbonated through the production of CO2 during fermentation. The home fermentation process requires the use of a starter SCOBY (symbiotic culture of bacteria and yeast) and sweetened tea.
The SCOBYs are available for purchase commercially but they can also be obtained locally from someone who brews kombucha. The SCOBY will continue to grow as kombucha is fermented, so home fermenters will eventually have excess SCOBYs they may be willing to share.
Homebrewing kombucha is a fun and creative process. Fermenting at home allows experimentation with different levels of pH, resulting in differing tastes of sweetness versus sourness. A second fermentation may be conducted with fruits, ginger, and other flavorings. At the Tenth Generation Farm, we have recently been experimenting with combinations of fruits we harvest from our farm, including pomegranate, fig, and desert natives such as prickly pear, wolfberry, and desert hackberry. Thus far, the prickly pear has been our favorite. We have also tried other flavorings such as ginger, strawberry, and kiwi. For flavoring, we have blended and strained fresh fruit and purchased 100% juice and juice concentrate. There are countless delicious combinations. There are many instructional videos posted online to learn the process of fermenting at home, which is how we got started.
Kombucha contains live beneficial bacteria and yeasts, organic acids, B vitamins, antioxidants, and trace minerals. Added juice or flavorings may contribute nutrients as well. With only about 30 calories and 2-3 grams of sugar per 8 ounces of unflavored kombucha, kombucha can be a refreshing, low-calorie beverage. (4)
Sauerkraut and kimchi are fermented foods typically made with a cabbage base. Other vegetables are often added for variety. Sauerkraut has roots in Old Europe, while kimchi hails from Korea. Traditional sauerkraut is made from cabbage, while kimchi is made with Napa cabbage, daikon radish, garlic, and hot peppers. Kimchi can be eaten as is, or used in a variety of recipes.
The University of Arizona Cooperative Extension has published AZ1748, Taste of Korea: Kimchi. This publication discusses the history and health benefits of kimchi and provides instructions and recipes. Similarly, the University of Wisconsin Cooperative Extension has authored a paper on making sauerkraut, B2087, Make your own Sauerkraut.
The University of Minnesota also has an article titled How to Make Your Own Sauerkraut
Both sauerkraut and kimchi are fermented with a brine (salt) solution. The ingredients are packed into jars, covered with brine, and tamped to remove air bubbles. The vegetables must remain submerged in the solution, so weights are used to keep the food below the surface. Weights include plastic bags partially filled with water or commercially available glass weights. It is also important to prevent oxygen from entering your container during fermentation.
The fermenting process will release gas that will pressurize the container. The lid should be loosened every day or two to allow the pressure to escape, then tightened. An automatic option is to use an air-lock that will allow gas to escape but not allow air into the jar. There are many types of airlocks available. The one I use is the Jillmo, which includes metal jar lids and plastic airlocks. If you prefer glass, there are glass airlocks available for purchase.
Kimchi may be fermented and ready in as little as two days. Sauerkraut can require three to four weeks, but the process can be stopped earlier to suit your taste. Longer fermentation produces more probiotics, but also creates more sourness. When you are ready to end the fermentation process, consume the food or place the container in the refrigerator. Refrigeration slows the fermentation process considerably.
There is almost no limit to the type of vegetables that can be fermented. You can experiment using your homegrown produce and try out new ideas. At our farm, we've recently tried fermented peppers and onions with spices. We own several books on fermentation that give us a plethora of ideas and recipes because we are always looking for new ways to preserve and enjoy our garden produce.
The use of fruit my be problematic when it comes to fermentation. The high sugar content in many fruits enables spoilage, or the product may turn alcoholic. However, if you would like to make and enjoy alcoholic drinks from your fruit kombucha, there are many resources available to provide instruction.
Kefir is a fermented milk beverage, also started from a SCOBY. This type of SCOBY is referred to as “kefir grains.” As the milk ferments, it thickens slightly. Like kombucha, longer fermentation results in a lower pH for a more sour taste. After fermentation, the SCOBY is strained out and used to start the next batch of kefir. The University of California Cooperative Extension Master Food Preservers has published a publication titled Fermentation: Kimchi, Kombucha, Kefir, which contains instructions and information.
Enjoy your garden harvest in healthy new ways with fermentation.
1. Jarvie, M. (2014, April 3). Interested in making your own home-fermented foods? Retrieved 2018, Oct 4 from http://www.canr.msu.edu/news/interested_in_making_your_own_home_fermented_foods
2. Marco, M., Heeney, D., Binda, S., Cifelli, C., Cotter, P., Foligne, B., Ganzle, M., Kort, R., Pasin, G., Pihlanto, A., Smid, E., and Hutkins, R. (2017, April). Health benefits of fermented foods: microbiota and beyond. Retrieved Oct 2018 from https://isappscience.org/wp-content/uploads/2017/01/Marco-health-benefits-fermented-foods-ISAPP-rev-17.pdf
3. Shockey, K. and Shockey, C. (2017). Fiery Ferments. North Adams, MA: Storey Publishing
4. Colorado State University Extension, Colorado Farm to Table Food Safety (nd). Understanding and Making Kombucha. Retrieved September 2019 from http://farmtotable.colostate.edu/prepare-ferment/kombucha.pdf
Extension publications mentioned:
University of Arizona Cooperative Extension Publication az1748, Taste of Korea: Kimchi. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1748-2017.pdf
University of Wisconsin Cooperative Extension Publication B2087, Make your own Sauerkraut: https://learningstore.uwex.edu/Assets/pdfs/B2087.pdf
University of Minnesota Extension Publication How to make your own sauerkraut, https://extension.umn.edu/preserving-and-preparing/how-make-your-own-sauerkraut
University of California Cooperative Extension, Master Food Preservers Publication, Fermentation: Kimchi, Kombucha, Kefir: http://mfp.ucanr.edu/files/263972.pdf