A brief overview of Lactic Acid Fermentation
What is Fermentation?
Fermentation is the production of energy from nutrients in an anaerobic environment (anaerobic = without oxygen).
It can take place in many forms, but this document will focus on Lactic Acid Fermentation.
Lactic Acid Fermentation is undertaken by microorganisms called Lactic Acid Bacteria (LABs). They are Friendly Bacteria!
Some of the usual suspects are Lactobacillus Plantarum, and Leuconostoc Mesenteroides, but there are many more such as Lactobacillus Acidophilus, Bifidus and more.
In simple terms LABs convert the simple carbohydrates in food (a.k.a sugars) into lactic acid, and multiply if given favourable conditions.
In doing so, they raise the acidity of the food substrate (or lower the PH) and kill off other unwanted pathogens that are present (albeit minimally) in all naturally derived food sources.
LABs also produce carbon dioxide as a byproduct, which increases their predilection for an anaerobic environment, and again makes it harder for the nasties to cohabitate.
Because they like (and help create) acidic environments - LABs can survive exposure to our stomach acids and live lower down in the gut.
History
Many Historians and Biologists believe that our controlled use of fermentation is most likely older than our controlled use of fire.
The beneficial microbes associated with fermentation have evolved in symbiosis with the human race and they are present (in one form or another) in all our cultures and societies.
Some examples of human assisted fermentation include Yogurt, Beer, Wine, Cheese, Sauerkraut, Kombucha, Kimchi, Miso, Sourdough Bread, Injera Bread, Ginger Bugs, Dairy Kefir, Water Kefir, Lassi and many more.
Why Ferment?
There is a good reason for this symbiosis - and that is that we need friendly bacteria in order to maintain good health!
The human body contains over 10 times more microbial cells than human cells.
This ecosystem of small things is often referred as our Microbiome - a mix of microscopic organisms that coexist in a defined space - being us!
The microbiome of the gut is so important that it has been referred as a “forgotten organ”.
Fermented foods are outstanding sources of essential vitamins and nutrients such as Vitamin K2 - which helps to prevent arterial plaque buildup and heart disease.
In days gone by Sauerkraut was one of the major sources of Vit C. Dutch Sailors (who did not grow many oranges) used to take fermented vegetables aboard their ships to keep scurvy at bay.
The process of fermentation potentiates the ingredients - amplifying their nutritive qualities. If you ferment with health benefiting spices and herbs, they will become more effective than in a non-fermented state.
Research indicates that a healthy microbiome plays a very important curative role in the treatment many human diseases and maladies.
Conversely - a depleted microbiome can also be attributed to the onset of many undesirable diseases and conditions.
In the last few generations (especially in the West) we have lost our connection to fermented foods, and only recently have we begun to intellectually understand why they are embedded in the cuisines of every human culture in the world.
One contributing factor to the demise of fermentation in our society is the advent of Pasteurization as the go-to food preservation method of our times.
Artificial preservatives have also impacted on our many fermentation-inclusive approaches to food preservation.
We have also increased our dependency on Pharmaceutical Antibiotics to treat many unfriendly bacteria and pathogens. While Antibiotics do offer short term benefits, one often overlooked side effect is that fact that they also kill friendly bacteria and work in opposition to a healthy gut microbiome.
Organic, uncooked, fresh foods contain trace amounts of probiotics in them, but when we eat food with low nutritional value (like McDonalds), not only do we not support a healthy LAB rich microbiome, but in the absence of healthy gut flora - we allow room for other nasties (like Candida Albicans) to colonize and negatively impact our health.
We are an Ecosystem!
I like to think of our gut microbiome as a river ecosystem that goes from our mouth to our bum. Rivers are the lifeblood of landscape effecting all the birds, animals, forests, fishes around and within it.
Events that occur upstream in a river directly impact things downstream.
Rivers can be polluted by human abuse, or have their supporting forests clear felled. When that happens, the natural order is compromised and indigenous lifeforms are replaced with other invasive species.
Once the decline sets in - it can get harder and harder to restore equilibrium.
Healing ourselves, and our gut is a bit like a regenerative land-care scheme. We need to stop erosion, and proactively reintroduce the indigenous resident lifeforms (LABs) in order for the whole ecosystem to regain it’s vitality.
We are an ecosystem - and our gut microbiome does not live in isolation to the upstream choices we make when it comes to what is on our plate at dinnertime.
An estimated 80 percent of your immune system is located in the gut.
Probiotics play a crucial role in the development and operation of the mucosal immune system in your digestive tract, and aid in the production of antibodies.
We have a Gut-Brain Connection. Several recent studies have shown that the state of the “little brain” in our gut (a.k.a The Enteric Nervous System) can directly influence our state of mind and help with conditions such as Anxiety, Depression and more.
In summary:
A healthy gut is critical to maintaining optimal health through a robust immune system.
Consuming fermented foods is a great way to get a healthy gut.
Fermenting your own food is not only fun - but it’s much cheaper than buying probiotic capsules from the Health Food Store, or even buying fermented products from your supermarket like Southern Wild’s!
How to Ferment
The key technological factors for vegetable fermentation are:
- Your ingredients
- The degree of salinity
- The exclusion of oxygen
- The surface area to volume ratio of your ingredients
- The relationship between temperature & time
- Wild Fermentation VS Starter Cultures
Ingredients
Our friendly LABs are very sensitive to chemicals.
Therefore using Organic or Chemical-Free ingredients is very important for fermentation.
The probiotics we are trying to colonize in our guts are already alive on the surface of organically naturally produced, uncooked, fresh food.
Cabbage alone has over 30 probiotic strains living in it.
Using Chemical-Free water is also very important if you plan to do any brining.
Salinity
Salinity creates an enjoyable environment for our LABs. This allows them to thrive at the expense of other undesirables.
It is important to use mineral rich unrefined salt. Salts that are refined and contain anti caking agents (such as Iodine) have been known to negatively effect our ability to colonize the LABs.
We like using Sea Salt - the locally farmed Tasman Sea Salt is fantastic.
When we salt the vegetables, the salt pulls the water from them, and by creating a brine substrate we further reduce the amount of oxygen in the fermenter, which the LABs also love.
One of the reasons why cabbage is so commonplace with vegetable fermentation is the fact it can release a lot of water.
How much salt you use is quite important. The less salt you put in, the more likely the ferment is to putrefy. The more salt included, the longer you can ferment - but you don’t want too much salt for health’s sake.
We often use our ferments as a substitute for applying salt to prepared dishes. Sauerkraut in soups, salads or sandwiches is great!
We typically use between 1.5% and 2.5% salt by weight.
Due to the wide amount of variance in salt crystals (flakes, rocks, grains) it is better to weigh your salt rather use than volumetric measurements like cups, or tablespoons.
As an example of high-salt fermentation. Some Misos have 15% salt and typically ferment for several years in cold conditions.
Conversely - you can make low-sodium “young ferments” to consume within a week or two.
You can definitely experiment with salting to taste. It is typical for the process of fermentation to reduce the sense of saltiness over time.
A good guideline is to taste your ferment at the beginning, and salt it to a little more than you would consider optimal, and this will mellow to perfection when it is ready.
Surface Area to Volume Ratio
There is a direct relationship between the available surface area in chopped vegetables and the LAB’s ability to consume them.
The more surface area that is available, the more the LABs can digest the simple carbohydrates in the vegetables.
However - if vegetables are sliced too thinly, the salt applied can pull too much liquid from the vegetables and you will get a mushy result.
When your vegetables are cut too thickly - the fermentation can take months or even years to achieve readiness.
Typically, 3-5 millimeter thickness for cabbage slices is a good place to start.
If you are combining different vegetables in your ferment it can be fun to experiment with different sizes for vegetables of varying hardness.
For example - if you add Carrot to a Cabbage ferment. Carrot is harder, but if you shred it finer than the cabbage, it will probably achieve a similar texture when fermentation is complete. Of if you shred it to be larger than the cabbage it will probably stay much harder - and this may be a good thing!
Temperature & Time
The optimum temperature for fermentation is about 18-22 degrees Celsius.
The hotter is gets, the faster the process will go.
It can be too hot - where the various strains of LABs will not evolve properly in their respective life cycles and the flavor becomes compromised.
Whereas colder does not negatively effect the flavor, but it can slow the process down dramatically.
Maintaining a consistent temperature is ideal - avoid fermenting in places that experience wide variances in temperature.
The vessel you ferment in can help with this and ceramic crocks are great in that they insulate the fluctuations in outside temperature.
In terms of timing, at optimal conditions of around 19 degrees I like to ferment for around 21 days.
Due to the dynamic relationship between temperature and time there can be no fixed rule unless you are fermenting in a laboratory.
As a general rule we ferment at home for a minimum of 5 days when the outside temperature average is around 19 degrees.
A lot of research shows that by fermenting longer you get a wider spectrum, and increased populations of LABs - which makes the ferment better for you.
One golden rule applied for optimal fermentation is to ferment around 21 days at 19 degrees Celsius to get a good balance of flavor and LABs.
Different LABs evolve at different stages of the process (as acidity increases).
- L. Mesenteroides begins days 0-3
- L. Plantarum - days 3-16
- L. Pentoaceticus - days 16+
Wild Fermentation VS Starter Cultures
When it comes to inoculation - there are three main approaches to fermentation:
Wild Fermentation - just adding salt and mixing the vegetables and letting the native LABs evolve in the vessel naturally. This approach is very safe and can produce excellent flavors but the propensity to get variances in different batches is high.
Backslop - this means adding some of your old ferment brine to the new batch. you pre-colonize the ferment and give it a head start, but the backslop usually ensures that you have a fairly wide spectrum of LABs that are being inoculated. If you continue to use a backslop you will likely get increased consistency of flavor over multiple generations compared to Wild Fermentation.
Starter Cultures - you can buy starter cultures of specific LABs and inoculate them into your batch to help with the fermentation. This likely increases the propensity for consistency of flavor, but we personally find that the flavor possibilities are reduced as a result of promoting only 1 or 2 strains of LAB. You also pay extra for the culture when mother nature provides it free of charge.