Lacto fermentation is a natural, biological process caused by beneficial microorganisms. Good bacteria cause a change in the make-up of food products, creating lactic acid which lowers the pH (more acidic) and increases the nutritional value of the fermented food.
Fermented food is easier to assimilate because it is already “chewed and digested” by the bacteria. Therefore, vitamins, minerals, enzymes, and other nutrients are more fully absorbed by the body.
- Food processed by microorganisms is highly bioavailable
Consuming lacto fermented food benefits the entire digestive tract, helping it to remain in balance.
Lacto fermentation describes a biological process when microorganisms convert sugars in vegetables and milk into lactic acid.
Lactic acid is beneficial. And the more lactic acid present in food, the more acidic the taste will be. Lactic acid a main reason why fermented food feels tangy and refreshing.
- prevents growth of harmful microorganisms
- promotes growth of beneficial bacteria
- increases bioavailability of nutrients
- help control intestinal infections
- acts as a natural preservative
- makes food easier to digest
Three simple principles
These principles apply to most vegetables fermented at home—sauerkraut, fermented garlic and many others. A successful lacto-fermentation means sticking to these principles. If you fail, problems will occur
Unwanted microorganisms can disturb the fermentation process by producing butyric acid and other bad-smelling substances. Because of this, the final product may not be fit for consumption. This has happened to me a few times so I’ve learned much from my own mistakes.
Follow three main principles:
- Correct salt concentration
- Correct temperature
- Absence of oxygen
1. Salt concentration
Between 1-3% of salt is viewed as a good range. I use Himalayan or sea salt in my recipes.
Lactic acid producing bacteria often tolerate high salt concentrations. Adding salt promotes the fermentation and prevents the growth of non-desirable organisms.
- Starter cultures work better with salt
The bacteria strain Leuconostoc (found in kefir, sauerkraut, and vegetables) has a high salt tolerance and initiates fermentation. The added salt extracts juice from the vegetables and creates brine.
I recommend to always use a starter culture. Try the excellent celery juice as brine. It has properties that help preserve the vegetables fresh. But the final product will not taste celery, in fact, you hardly feel it at all.
Traditional fermentation without a starter
Vegetables are placed in a layer of about 2.5 cm (one inch) depth in the fermenting container. Salt is sprinkled over the vegetables. Another layer of vegetables and salt is added, and this is repeated until the container is three-quarters full. A cloth is placed above the vegetables and a weight added to compress the vegetables and assist in the formation of a brine which takes about 24 hours. As soon as the brine is formed, fermentation starts and bubbles of carbon dioxide appear. It ferments for about a week, then stored in a cool place.
Most lactic acid producing bacteria work best at temperatures of 64 to 72 degrees (18 to 22ºC). However, there’s a wide range of possible fermentations making each batch unique.
Here are a few general facts to consider:
- Most probiotic bacteria prefer 68 to 86 degrees (20 to 30ºC) (fermented vegetables, sauerkraut, fermented dairy)
- Some bacteria, like the thermophiles (in yogurt) prefer a bit warmer temperatures 120 – 130 degrees (45-5OºC, close to a radiator)
- Other bacteria like it cooler. One example is Leuconostoc species involved in lacto fermentation. They have an optimum of 64 to 72 degrees (18 to 22ºC)
- Generally speaking, temperatures above 72 degrees (22ºC), favor more the lactobacillus species.
If you ferment in a warm climate, you might have difficulties with the lacto fermentation process simply because the high temperature will promote the growth of yeast and unwanted bacteria. Using a starter culture helps.
Even though some bacteria require oxygen for their metabolic activities, lacto-fermentation at home works best in the absence of oxygen. Using air-tight jars is therefore important.
NOTE: During the first part of fermentation don’t put the lids on too tight. Gas is produced and pressure can build in the jars. Open the lid for a second daily to let the gas out. When storing the jars in the fridge the fermentation process calms down and lids can be screwed on tighter to keep air out.
Three phases of lacto-fermentation
It starts with “breaking down” of substances in the vegetables. This first phase if short, only a few days. You might see bubbles and brine coming out of the jars. This is normal. During the first phase, most harmful microorganisms are destroyed as the veggies turn increasingly sour.
Good bacteria are now in complete control of the jar and consume sugars contained in the vegetables. Lactose, glucose, fructose, and sucrose are all converted by the bacteria into lactic acid and many other potent substances.This gradually increases the bio-availability of nutrients.
The level of acidity increases slowly in the brine and this creates the familiar tart, tangy flavor in fermented food. The acidity helps preserve the vegetables since most harmful bacteria do not survive in such an environment. The more lactic acid, the more acidic the flavour.
Storing the jars in a cool place slows down the lacto-fermentation process. However, the probiotic bacteria are still alive, slowly consuming carbohydrates and producing a range of potent substances. The bacteria can stay alive in the jars for many months. The longer you store the jars, the more tart and complex aromas are created.
Using starter cultures
Several bacteria species are involved in the natural or wild lacto- fermentation process. The bacteria naturally occur on vegetables and in raw milk.
However, a starter culture controls which bacteria strains take control in addition to the ones naturally present on the veggies. Bacteria in the starter culture will dominate the process from start to end.
Starter cultures have many benefits:
- More lactic acid
- Fewer problems
- Predictable result
- Stable fermentation
- Easier fermentation
- Can be consumed faster
- More beneficial bacteria
In addition to the desirable bacteria, there are a range of undesirable micro-organisms present on cabbage and other vegetables which can interfere with the fermentation if allowed to multiply unchecked.
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.
Here are a few examples of bacteria involved in lacto fermentation.
Yogurt: Fermenting milk into yogurt involves Lactobacillus bulgaricus, Lactobacillus acidophilus, and Streptococcus thermophilus.
Kefir: A milk drink using cow, sheep, goat milk or even soy, rice or coconut milk. Originates in the Caucasus region. 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. Read more on preparing sauerkraut.
- 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 mostly soybeans. Miso is a natural food containing healthy microorganisms such as Tetragenococcus halophilus. As probiotics bacteria can be killed by over-cooking, add the miso to soups or other foods just before they are removed from the heat. Or use miso without any cooking at all.
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.
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.
Lacto fermentation in all forms is an amazing process. Be sure to consume plenty of it!