Lacto-fermentation is an amazing process! It creates delicious yogurt, kefir, kombucha, natto, kimchi, and many other fermented foods. Lacto fermented food is highly bioavailable and packed with beneficial microorganisms. One of my favorites is fermented whole tomatoes—something I discovered when visiting friends in Eastern Europe. I’ve done my share of mistakes and ruined a few batches along the way. I will explain how you can avoid the same mistakes.
But what is lacto-fermentation?
What is lacto-fermentation?
Lacto-fermentation is natural, biological process involving friendly microorganisms that change the makeup of vegetables and dairy. During this process they produce lactic acid which creates the familiar acidic taste. Lacto-fermented food is easy for the body to assimilate because the nutrients has already been “chewed and digested” by the bacteria.Health benefits of fermented foods – PubMed (nih.gov)Health benefits of fermented foods: microbiota and beyond – PubMed (nih.gov)Increased iron bioavailability from lactic-fermented vegetables i(nih.gov)
During fermentation, probiotic bacteria and other microorganisms produce powerful enzymes, vitamin K2, lactic acid, hydrogen peroxide, benzoic acid. Fermented food contains a number of antibiotic and anticarcinogenic substances.
Fermented food has already been chewed and digested by microorganism.
What does the lacto-fermentation process accomplish?
- It prevents the growth of harmful microorganisms;
- creates a number of new beneficial compounds;
- promotes the growth of beneficial bacteria;
- increases bioavailability of nutrients;
- acts as a natural preservative;
- makes food easier to digest;
- promotes a body detox.
Summary: Consuming fermented food is far better and more cost-effective than probiotic supplements. Food processed by beneficial microorganisms is highly bioavailable and supports your body’s intricate eco system of microorganisms. This keeps the gut in balance, detoxes the body, and controls your weight and even mood.Yogurt and gut function – PubMed (nih.gov)Gut Bacteria May Play a Role in Autism – Scientific AmericanPhysiological properties of milk ingredients released by fermentation – PubMed (nih.gov)
Three requirements to succeed
These requirements are simple but essential if you want to succeed. When fermentation is complete, the jars should be stored in a cool place like a cellar or fridge. We have noticed that the taste of lacto-fermented vegetables improves and matures for several months during storage. The taste tend to become more complex and tangy.
- Correct salt concentration
- Correct temperature
- Absence of oxygen
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1. Salt concentration
Between 1-3% of salt is viewed as a good range but there’s no need to be too picky as lactic acid producing bacteria (probiotics) tolerate high salt concentrations. For example, the Leuconostoc bacteria often initiates fermentation both in kefir and sauerkraut and it has a high salt tolerance.
How much salt to add:
- Add 1-3 tablespoons for every medium head cabbage or equivalent amount of other vegetables. Mix the salt with the shredded vegetables.
- A second option is to dissolve 1-3 tablespoons in every quart of brine. I like to juice celery stalks or cabbage for brine. If you don’t have a juicer, you can also mix the salt in water and use it as brine.
- I use Himalayan or sea salt in all my recipes.
Traditionally, lacto-fermented vegetables was prepared without a starter. This is called a “wild fermentation” as it utilizes the bacteria naturally present on raw vegetables. Much salt was used to preserve the veggies and prevent harmful microorganisms to develop. Wild fermentation works well if you know what you are doing. However, it is better to use a good starter culture when fermenting.
I also think that the fermented vegetable become crispier and crunchier if salt is added salt.
Summary: Adding salt when fermenting vegetables promotes crunchiness, improves taste, protects the veggies from unwanted microorganisms, and helps preserve the product longer. Many starter cultures work better when salt is added. Use Himalayan or sea salt; avoid standard table salt.
When fermenting vegetables, probiotic microorganisms are most productive at temperatures between 64 to 72 degrees (18-22º C). If it’s cooler, it might require more time to ferment. However, many problems can occur when it’s too warm.
Here are a few facts to consider:
- A temperature around 72 degrees or more (22ºC) favors lactobacillus species. (fermented vegetables, sauerkraut, fermented dairy)
- Some bacteria like it cooler, as Leuconostoc species with an optimum of 64 up to 72 degrees (18 to 22ºC)
- When making yoghurt, species like thermophiles prefer 120-130 degrees (45-5Oº C which is close to a radiator)
If it’s too warm during fermentation, mold and unwanted bacteria can easily develop. Once I put my jars to ferment in a cabinet close to the stove which ruined my entire batch because the temperature became too high when using the stove.
Summary: Correct temperature is essential for your batch to turn out well. The vegetables tend to become more mushy when it’s too warm so stick to a range between 64-72 F (18-22º C).
Lacto-fermentation works best in the absence of oxygen. Therefore, using air-tight jars is important. However, during the first few days of fermentation pressure builds in the jars so don’t screw the lids on too tight. You can also open the lid for a second now and then to let gas out. After fermentation, lids should be screwed on tighter to keep air out.
As you can see from the images, I use jars with a rubber seal that allows excess gas to leak out but no oxygen is allowed in. When fermentations starts, some brine might leak out which is normal.
This is also the reason why the vegetables should be submerged in brine. Therefore, add enough brine to each jar so it completely covers the veggies. I always add a cabbage leaf on top of each jar which help to keep the veggies in the brine. Discard the leaf when you start consuming the vegetables.
Three phases of wild lacto-fermentation
Lacto-fermentation is an amazing, natural process in which beneficial bacteria cooperate in stages to produce the delicious, tart taste. Certain bacteria species initiates fermentation, other species continues this chain-reaction as the environment becomes more and more acid.
The first phase commences the “breaking down” of vegetables and lasts only a few days. Usually you see bubbles and brine is leaking out of the jars. During this phase, most harmful microorganisms are destroyed by beneficial microorganisms and the batch starts to turn increasingly sour.
The good bacteria are now in complete control of the batch and consume sugars contained in the vegetables. Lactose, glucose, fructose, and sucrose are all converted by the bacteria into lactic acid and other substances. This process gradually increases the bio-availability of nutrients.
The level of acidity increases slowly in the brine, thus creating the familiar tart, tangy flavor of fermented food. The acidity preserves the vegetables since most harmful bacteria don’t survive in such a sour environment. The more lactic acid that is produced, the more acidic the flavor.
Storing the jars in a cool place slows down fermentation. However, the beneficial microorganisms are still alive, slowly consuming carbohydrates and producing a range of potent substances. Good bacteria can stay alive in the jars for many months. The longer the jars are stored, the more tart and complex aromas are created.
The longer the jars are stored, the more tart and complex aromas are created
Summary: Three phases are involved in wild fermentation of vegetables. This is because different probiotic bacteria species are most productive in each of the three stages. One reason for this is the increasingly acidic environment that promote certain species.
Using starter cultures
Several microorganism species are involved in the natural or wild lacto- fermentation process. These bacteria naturally occur on raw vegetables and in raw milk. Most starter cultures will include such species.Lactobacillus plantarum with Functional Properties (nih.gov)
The bacteria in a starter culture will quickly take control of a batch together with the ones naturally present on the veggies. Bacteria in the starter culture usually dominate the fermentation process from start to end. This is a good thing as it suppresses the formation of unwanted microorganisms like mold.
Starter culture benefits:
- More predictable results
- More lactic acid is produced
- Fewer problems with batches
- Stable and easier fermentation
- The product can be consumed faster
- More beneficial bacteria in the jars
The quality of the final product depends largely on how well the undesirable organisms are controlled. Some bad bacteria use protein as an energy source, thereby producing unpleasant odors and flavors.
Summary: Using a starter culture when fermenting vegetables speeds up the process and ensures a more predictable result. A good starter usually contains 5-12 species, except in some cases like natto.
Examples of lacto-fermented foods
Here are a few examples of microorganisms involved in lacto-fermentation of different foods.Fermented Foods in Food Guides around the World (nih.gov)Fermented foods and Health Promotion (nih.gov)Worldwide review of household fermentation techniques – ScienceDirect
Yogurt: Fermenting milk involves Lactobacillus bulgaricus, Lactobacillus acidophilus, and Streptococcus thermophilus.
Kefir: Produced with cow, sheep, goat milk or even soy, rice or coconut milk. Kefir contains strains of Lactobacillus Caucasus, Leuconostoc, Acetobacter species, and Streptococcus species. Beneficial yeast is also involved.
Sauerkraut: Fermented cabbage. Strains of Leuconostoc are involved as well as Pediococcus and Lactobacillus strains like Cucumeris. Lactic acid bacteria are the primary group of organisms involved in sauerkraut fermentation. Here are a few:Probiotic lactic acid bacteria in treatment of inflammatory bowel disease – PubMed (nih.gov)Traditionally produced sauerkraut – PubMed (nih.gov)
- Leuconostoc mesenteroides – acid and gas producing
- Lactobacillus plantarum – produces acid and a little gas
- Lactobacillus pentoaceticus – acid and gas producing
Miso: Japanese ways of fermenting rice, barley and soybeans. Miso contains healthy microorganisms such as Tetragenococcus halophilus. The bacteria is killed by over-cooking so add miso just before serving.
Natto: Soybeans fermented with Bacillus subtilis. It contains enzymes and compounds with exceptional health benefits.
Kimchi: Often made from cabbage, radish, cucumber and other vegetables and seasonings like ginger, garlic, scallions and many other. It contains a number of bacteria, especially Lactobacillus kimchii.Kimchi, a fermented vegetable, improves serum lipid profiles – PubMed (nih.gov)Cancer Preventive Potential of Kimchi – PubMed (nih.gov)Health benefits of kimchi as a probiotic food – PubMed (nih.gov)
Kombucha: A kombucha culture often contains Gluconacetobacter xylinus and one or more of the yeasts Saccharomyces cerevisiae, Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, Torulaspora delbrueckii, and Zygosaccharomyces bailii.
Summary: Lacto-fermentation in its different forms is an amazing process in which vegetables, dairy, and other products are processed and transformed by microorganisms into highly bioavailable food. During this process, new potent compounds and enzymes are also created. Try to consume a wide variety of fermented foods!
Unwanted microorganisms can disturb fermentation by producing butyric acid and other bad-smelling substances. Because of this, the final product may develop a bad taste and soft texture. This has happened to me a number of times so I’ve learned to be careful to follow the three principles mentioned in this article. Another common problem is mold that can ruin the entire batch.
When fermenting vegetables became industrialized, many adjustments were made to render the final product more uniform and more saleable but not necessarily more nutritious. Some commercial products contain very little, if any, beneficial bacteria. Homemade fermented vegetables can contain trillions in a few tablespoons; that’s more than an entire probiotic supplement bottle.