Lacto-fermentation is a food preservation process that relies on salt to create a hospitable environment for gut-friendly bacteria. At the same time, it eliminating the growth of harmful food bacteria and fungi. These beneficial bacteria create lactic acid, which naturally preserves fruits and vegetables in a manner that best retains flavor, nutrition, and texture.
It’s an essential skill for the seasonal kitchen. It’s one of the safest food preservation techniques that actually makes foods more nutritious.
Read on the get the most of this comprehensive guide to lacto-fermentation!
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Lacto Fermentation | A Definition
When fresh vegetables and fruits are processed with salt, they produce a brine.
The salt pulls the liquids from the vegetables and fruits, and the salt dissolves in that liquid. The vegetables or fruits are submerged in the brine, where beneficial bacteria create lactic acid. The lactic acid preserves the food’s texture, flavor, and nutrition for an extended period of time.
Lacto-fermentation is the process of submerging fruits and vegetables in such a brine to create an environment without oxygen. Called an anaerobic environment, brines allow lactobacilli to thrive and thwart the growth of harmful microorganisms such as unwanted bacteria, yeast, and mold.
Lactic-acid bacteria (LAB) thrive in this anaerobic environment and produce lactic acid as they break down the sugars in the vegetables and fruits.
It is the lactic acid that preserves food. It keeps much of their nutrient content intact, for months and sometimes years.
We can make salt brines and submerge whole vegetables in it to create the perfect anaerobic food preservation environment as well.
The Chemistry of Lacto-Fermentation
Fermentation is a metabolic process that converts sugars (carbohydrates) into acid or alcohol.
When the fermentation process produces alcohol, it is called ethanol fermentation. This is the magical process that brings us beer, wine, sake, and hard ciders, among other wonderful adult beverages.
The fermentation process that converts sugars into acid is lacto-fermentation. That’s what we are here to explore today.
Let’s visit the 5 Minute School for a quick lesson on the science of it all!
In a nutshell, or fermentation crock as the case may be, shredded vegetables and salt create a brine. The vegetables are kept submerged under the brine where beneficial bacteria called Lactic Acid Bacteria (LAB) flourish. In this anaerobic environment, an environment without oxygen), the LAB grows and produce lactic acid. The lactic acid preserves the flavor and nutrition of the shredded vegetables.
What you get is a kraut or kimchi that is tasty, nutritious, and pro-biotic.
When you ferment a whole vegetable, it is called pickling. Whole or large pieces of vegetables like cucumbers or carrots, need to be submerged in a premade brine that is between 2-5% salinity. Each recipe you use will give you a salt to water ratio appropriate for that vegetable.
Salt encourages the growth of the LAB, retards and prohibits the growth of troublesome bacteria and yeast, and preserves the texture of the preserved vegetables.
Beginners should note that early fermenting mistakes almost always include using too much salt. You can use the free downloadable salinity chart as a reference for your ferments. this will be handy once you become more comfortable with the process and use recipes as a quick reference.
Fermented Foods and Gut Health
The LABs (Lactic Acid Bateria) in fermented foods are good for so much more than preserving your foods.
Lacto-fermentation creates foods that are probiotic, meaning that they supply a source of beneficial bacteria that are helpful for your microbiome.
Probiotic literally translates to ‘for life‘!
When our microbiome, the world of microorganisms that live in our bodies, is healthy and thriving, they aid digestion, boost immunity, and keep unwelcome bacteria away.
You can supplement with encapsulated probiotics, or you can ferment your foods and cultivate a microbiome specific to your local and seasonal environment.
Here’s an interesting story of how science first began to document the benefits of probiotics in the daily diet:
Russian microbiologist Elie Metchnikoff (1845-1916) was the first to associate the large amounts of fermented dairy products with the good health and longevity of Bulgarians back in 1907. He proposed that the acid-producing organisms in fermented dairy products could prevent what he called “fouling” in the large intestine. He believed if eaten regularly, these foods could lead to a longer, healthier life. One version of the Old Testament even attributes Abraham’s long life — 175 years — to the “consumption of sour milk.” Fermented milk products may have also been used to treat illnesses of the digestive tract during Roman times. ~ Harvard Health Publishing
What’s a Brine
Brine is a saltwater solution. It can be used to preserve food, as we have been discussing with this explanation of fermentation.
It can also be used to soak foods prior to cooking. It’s Thanksgiving week, and I’ll be placing my goose in a brine for 24 hours before it is cooked. That’s not fermentation, that’s brining.
As we’ve discussed, chopped vegetables can be worked with salt and a brine will result from the moisture in the vegetables. Whole vegetables can be submerged in a brine, using the salinity chart mentioned above, to make pickles.
The role of salt in lacto-fermentation
Salt brine in the early stages of lacto-fermentation keeps the unwanted bacteria and yeast away while the LABs have time to flourish.
You may meet people who want to ferment without salt because they believe the modern myth that salt is bad for the diet. Not only will it be near impossible to keep unwanted bacteria and molds from the ferment, but the end product will also probably be quite mushy.
Salt not only helps with the food preservation process, but it also helps retain some crispness of the vegetables as it pulls moisture during the process.
Salinity Chart for Lacto-Fermentation
You can use the free downloadable salinity chart as a reference for your ferments. Once you become more comfortable with the process and use recipes as a quick reference, it will be very handy.
Lacto Fermentation and Air | What’s an Airlock
First, the vegetables for your ferment have been submerged in a brine. then, you’ll need a way to keep oxygenated air from entering the fermentation chamber (crock, mason jar, etc.).
Oxygenated air will introduce unwanted bacteria, yeast, and molds to your ferment.
You help maintain an anaerobic environment with an airlock system that allows CO2 to escape from the ferment but block oxygenated air from re-entering.
There are a variety of ways to do this. Some will fill a plastic bag with brine and place it on top of the ferment to create a barrier. This is the cheapest way to create an airlock, and it is quite effective.
Then, there is a wide variety of airlock mechanisms that I find quite useful. You can see them in the Amazon links below.
Of course, the brine itself is an airlock and a good weight will help keep your ferment submerged. I have both ceramic and glass weights and love them both. When fermenting with weights as airlocks, I stir the ferment daily.
Here are some examples:
Lacto-Fermentation vs Canning | Not the Same
Canning, either with a hot water bath or a pressure canner seeks to sterilize foods for longterm storage.
Fermentation, as we’ve discussed, uses a natural process that preserves food with lactic acid.
I use both methods when preserving summer harvests for winter meals. I think that vegetables respond differently to various food preservation methods, but it is important to understand just how different they are.
If you would like to know more about traditional methods of food preservation, check out this post. It’s a fairly comprehensive list from some of the best food writers around.
My Fermentation Library
Managing a seasonal kitchen requires saving today’s harvests for tomorrow’s meals. It’s the only way to ensure local and seasonal ingredients are available year-round. If this explanation of lacto-fermentation has you intrigued, I have a growing library of fermentation recipes designed with the beginner in mind!
Click to try them out.
[Hint – the Dilly Beans are one of the most popular posts on the blog!]
Shelf Life and Storage of Fermented Foods
One of the BEST things about fermenting foods is that for many products, the longer they sit, the better they taste!
Ferments should be stored in a cool dark place. For most products, this means the fridge. I have a separate fermentation fridge that comes in handy during the fall when I have the most products.
Ferments can be stored for anywhere from 4 weeks to 18 months. It is very easy to tell if a ferment is off. Smell and texture will be clear signs that something’s not right.
As an aside, this is not the case with canning. If the sterilization process was not complete, deadly bacteria can lurk in the product. Canned foods should be rotated out of the pantry every year. You can read more about this risk here.
Food Preservation Boot Camp
Want a quick and easy Food Preservation 101 course? Take the FREE Food Preservation Bootcamp!
It’s a series of emails that give an overview of basic food preservation techniques, with recipes. The emails can be saved for future reference in your email system. So, no need to feel rushed or pressured through the course!
Click here or on the image below to learn more!
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- What is lacto-fermentation?
Lacto-fermentation is a food preservation process that relies on salt to create a hospitable environment for gut-friendly bacteria, while also eliminating the growth of harmful food bacteria and fungi. These beneficial bacteria create lactic acid, which naturally preserves fruits and vegetables in a manner that best retains flavor, nutrition, and texture.
- Is lacto-fermentation the same as canning?
No, lacto-fermentation preserves foods with beneficial bacteria, canning preserves food by sterilizing it thus removing any bacteria.