How Much Salt Should You Use to Ferment Vegetables | How to Ferment Vegetables
How much salt to use when fermenting foods is a very important question, that we are here to answer... with science! Thanks to microbiology, we now know what is safe when fermenting vegetables, the best salt to use for fermentation, how much salt to use when fermenting vegetables, and how long you should ferment foods for.
Everything You need to Know about Fermenting Vegetables
When you dive deeper into information about about something, you discover more, you learn more, you understand more... you can actually perfect a process, recipe, method, etc. by understanding the aspects and interworking of it fully...
Remember that time penicillin was created? and that time humans thought you could just throw antibiotics anywhere and everywhere and be healthier for it? Then we learned, and we studied, and we removed our ignorance on the subject. Through all the studying and mistakes made, we now know you can't do that. When scientists stopped focusing on the wonderful human applications of antiMICROBIAL drugs and focused on the microbes, they learned that antibiotic medicines were creating an environment in which antibiotic resistant superbugs would evolve. The moral of this story: you can't go around willy-nilly making things that are to have an effect on microbes, and then just completely ignore the microbes in favor of an anthropocentric view or opinion... Ignorance is bliss, but it's not safe. Lets remember this story throughout the duration of this blog post on fermented foods.
Anthropocentric: adj. Regarding humankind as the central or most important element of existence, especially as opposed to other creatures.
I never thought I'd be a science lifestyle blogger. But here I am. Scotty and I started the first ever microbiology lifestyle blog (that we know of anyway). The goal was to nerd out and blog about all things microbial AND to have the most instagram worthy pictures of food and life happenings. When we decided to venture into blogging we knew that we specifically wanted beautiful food photography, but what we wanted more was to provide factual, healthy information about the recipes we created.
I love seeing words like fermentation and microbiome and probiotic gain in popularity every day... but what I wish grew more is the number of people talking about the actual microbes involved. I've read so many fermentation recipe blogs and articles that provide an entire story on flavor profiles of the world with a full recipe, yet they don't once talk about the microbes. They might throw in the acronym "LAB"... or the word "lacto" but that doesn't even begin to explain it. Amongst the people who share fermentation recipes there is a severe lack of understanding of the most important ingredient in the fermentation: the microorganisms. Yes, it is super fun to play with flavor and spices and to explore the fermentation techniques of the world. However, what should be focused on first is the little creatures actually making the veggies into preserved probiotic power foods.
Now, I don't want this post to sound like I think negatively of everyone else who blogs about fermented foods, because that is not the case. I have gathered immense amounts of inspiration and flavor ideas from the fermentation blogs of the world. I'm so thankful that they exist. The non-scientific blogging community is extremely powerful and influential. Food blogs, health blogs, natural health blogs, vegan blogs, green living blogs... A lot of them are ridiculously beautiful and they all hold a great deal of influence. These blogs are what helped me to find confidence and passion in this blogging adventure. My goal for this blog post is more of a call to action. A call to action for others in the fermentation community to base the recipes they share, first and foremost, on the microbes involved.
People are often surprised at how much information we share about our process of creating fermented foods. I first learned about the microbiology of fermenting vegetables in one of my advanced microbiology lab classes at Louisiana State University. Taking what I learned, we innovated our own recipes for fermenting foods. Through extensive research of the microbes involved in vegetable fermentation and with a lot of testing and experimentation, we crafted methods perfect for probiotic microorganisms to thrive. Science is about educating everyone. We share our information because we aim to remove the fear and misunderstanding of fermented foods with thorough education and transparency. Fermenting vegetables isn't magic, and an in depth understanding of what is going on microscopically during vegetable fermentation is essential, especially if you are going to instruct and educate others on how to safely ferment foods at home.
If you really think about it..WE are not fermenting vegetables, the MICROBES are fermenting vegetables. We just have to set them up for success and watch it happen.
Fermentation is an ancient way of preserving foods. We know people have been fermenting without a background in microbiology for thousands of years. We definitely aren't the first people to do it, and we are not the first people to do it "right." There are many ways in which humans of the world ferment foods. Whether in wooden barrels, in a hole in the ground, in crocks, in glass jars... fermentation methods are eclectic and fascinating. The beautiful thing about ancient processes is that methods can evolve and improve over time. With technology and advances in the field of microbiology, fermented foods can be better and healthier than they were thousands of years ago. Learning about traditional fermentation methods, and how things were done generations ago is a wonderful experience. After all we have to understand where we come from. But why not adapt and grow to learn more each day about the microbial universe. Why not use scientific information to ferment smarter, healthier, and better than ever before? Thousands of years ago people didn't even know what microorganisms were. They had no idea that tiny living things were to credit for their vegetables being preserved after adding salt.
There is an argument always thrown my way over salt concentration, especially by people who just will not accept that using tablespoons to measure salt is not okay. It sounds a little something like "people have been fermenting for thousands of years and they didn't need science." Well I have three things to say about that: 1. "They" also lived in a less toxic world where agriculture was different, salt was different, microbes were different and antibiotic resistant bacteria didn't exist. 2. No, people didn't always use science to ferment... but they have used weight measurements for recipes, trade, and calculations for a LONG time. A long time meaning since around 1200 BC at least. People of the Eastern world used mass and math to make fermented vegetables for thousands of year. Not tablespoons. 3. Salinity or salt concentration can ONLY be determined using the mass of the salt. 1 tablespoon of two different types of salt weighs two completely different things, so if you're telling people to use any salt they want, but use a tablespoon because it creates a certain salinity, you're lying.
The scientific community now knows so much about the bacteria involved in vegetable fermentation... all that knowledge definitely needs to be factored into fermenting foods and developing fermented food recipes. Let us spread the best fermentation methods and recipes we can, by focusing on microbiology. Microbes are the ones doing all the work anyways.
Accurate salt concentration, providing adequate time for the fermentation to proceed, and proper temperature are necessary for a healthy population of microbes to develop in a vegetable fermentation. The temperature for vegetable fermentation should be between 70-80 degrees F. Once the temperature is established the two main factors that need to be tailored to the microbes are 1. Salt concentration and 2. length of time for the fermentation. If all of these things are accounted for appropriately, the pH of the fermentation will drop, lactic acid will build up, the microbial population will consist only of probiotic bacteria, and the vegetable matter will be preserved.
How Much Salt Should You Use to Ferment Foods?
"The amount of salt isn't that important." "You can't mess up fermentation, it's safe" "Just sprinkle some salt and leave it for a week" "There's supposed to be yeast in fermented vegetables"
I've heard all of these statements from people who claim to be educators on vegetable fermentation. Which is quite disappointing. Salt concentration is the most important factor, and without proper salt concentration you can indeed mess up fermentation. You don't just "sprinkle salt and leave it for a week." Salt concentration must be calculated using mass, and vegetable fermentation absolutely takes longer than a week. If done properly, at the end of the fermentation process only bacterial species should be present.
When microorganisms are grown on petri dishes in the lab, they are grown on very specific media with specific nutrients (or lack thereof) and specific concentrations of salts and minerals. Sometimes even a 1% difference in salt concentration of microbial growth media determines if the microorganism inoculated on a petri dish will even grow at all. One percent may seem tiny to us macro-organisms, but that difference is a big deal to bacteria, the tiniest of all living things.
Salt concentration is the first step in establishing a safe fermentation environment. Particular concentrations of salt pave the way for creating a happy home for lactic acid producing bacteria. These bacteria are species of Leuconostoc and Lactobacillus. It isn't about how salty or not salty you like your fermented vegetables. It is about the home you are supposed to create in order for these beneficial bacteria to thrive. All the microbes needed to get the fermentation process started are already present on your vegetables, even after you wash them. Once you provide the proper salt concentration, bacterial succession can occur and lactic acid can be adequately produced.
In order to provide the microbes present on the vegetables with the goldilocks principle of salt, the concentration that is just right, you must use units of mass to measure your salt. There are two mathematical ways to create an exact percent salt solution.
PSA: Using the metric system is much easier because 1 mL of water weighs 1 gram. So there is no mathematical conversion between mL and grams measurements of water in the metric system.
Creating a 2.5% total salt concentration would be done like so: on a scale with a bowl zeroed out, add 2.5 grams of salt to the bowl, then add your produce and any water into that same bowl up to 100 grams. That's a 2.5% total salt concentration.
What we do is slightly different and easier: We weigh all of our produce and water, multiply that weight by 2.5%, and add the number we get in salt.
Example: If we have 100 grams of produce and water we multiply by 2.5%. So 100 x 0.025 [you have to move the decimal because you are multiplying by a percentage] = 2.5. So we add 2.5 grams of salt. This ends up being a 2.44% total salt concentration.
In order to calculate a total percent salt concentration you divide the grams of salt by the total grams of the whole solution: 2.5 grams of salt / 102.5 grams (of salt + water + produce) = 0.02439.
Move the decimal to make it a percent and you get 2.44% And guess what? With this method, we end up with 2.44% salt, no matter the weight of vegetables or water... as long as you multiply and weigh your salt:
For example, If we have 756 grams of cabbage and water, we multiply that by 2.5% it equals 18.9. So we add 18.9 grams of salt.
18.9/(756+18.9) = 0.02439 [that's 2.44%].
The only way you will get a consistent salt concentration throughout different batches of fermentation is by weighing the produce and water, doing math, and then weighing out your salt.
Two reasons to weigh everything and do math to determine salt concentration: 1. between batches the weight of vegetables you are fermenting will vary 2. sodium chloride is an ionic compound with a mass... salinity can only be determined by weighing the salt.
Depending on what salt you are using the amount of NaCl in a volume measurement, such as a tablespoon, varies greatly.
Unrefined sea salt can be found in many different "grains", such as flake, large grain, small grain etc. A tablespoon of flake salt has a mass of about 1 gram. A tablespoon of small grain Himalayan salt has a mass of about 3 grams. If you added the tablespoon of flake salt to 100 grams of vegetables and water you get a 0.99% salt concentration. If you add the tablespoon of Himalayan salt to 100 grams of vegetables and water you get a 2.9% salt concentration. Thats a huge difference, and the 0.99% salt concentration is completely unsafe, and will not select for probiotic microbes to thrive.
The minimum total concentration of salt that we've used with successful results is 2.25%
Percent salt concentration can only be determined by using the mass, and the percent salt needed depends on the vegetables in question. Vine growing vegetables tend to need 3% salt added. Low growing vegetables, such as cabbage need 2.5%. Root vegetables tend to only ferment well in the presence of other vegetables like cabbage.
We do not suggest fermenting beets or carrots by themselves due to the sugar content. Also, when we say "Vegetable Fermentation" we are not referring to the fermentation of legumes or starchy root vegetables.
How Long Should You Ferment Vegetables?
For the best probiotic microbes to thrive and produce lactic acid, the substance that actually preserves the vegetables, bacterial succession must occur. Bacterial Succession is when the growth and metabolism of one bacterial species increases, permanently altering the environment.
This leads to the death of that species and the takeover of a different type of bacteria. As one type of bacteria dies off, the next species takes over until the ferment reaches a point with perfect living conditions for species of Lactobacillus (which are probiotic bacteria).
If you do not add a proper salt concentration to the vegetables (calculated by using mass), bacterial succession will not take place, an anaerobic environment will not be formed, lactic acid will not build up, and the pH will not drop sufficently. This means that without first a proper salt concentration, then an adequate amount of time to ferment, the vegetable fermentation is not safe to eat, it is not preserved, and potential pathogens such as pathogenic yeasts and Clostridium spp. could be present.
Y'all.... Time is SO important. You've got to give the vegetable fermentation enough time to do its thing. I've seen recipes that say to leave a ferment on a counter for THREE days. I can guarantee you that it takes longer than 3 days. That makes me shiver with fear and disgust. When using wild natural microbes and a correct salt concentration to produce fermented foods, bacterial succession takes time and occurs in three stages that take 2 to 4 weeks. The time depends on the vegetable being fermented, but I promise it will always be longer than a week and definitely longer than three days.
Bacterial succession and the stages of fermentation make foods safe, delicious and nutritious. With the addition of a proper salt concentration, bacterial succession can begin. Next an anaerobic environment is created by oxygen utilizing microbes, then the production of lactic acid can occur. Once in stage three there is a very selective environment within the fermentation vessel, where only probiotic bacteria can thrive; bad microbes have already died off and are inhibited from growing. The key is providing an adequate amount of time for this process to occur.
Once you've weighed your salt, mixed your vegetables and water, and secured everything below the brine in your fermentation vessel using a fermentation weight, the following timeline will ensue:
Stage one: Stage one of microbial fermentation begins as soon as you add the salt to your veggies. There are many bacteria naturally on your vegetables that can tolerate salt, and the ones that utilize oxygen proliferate first. In this stage it's the Gram-negative rod shaped species of bacteria, like Enterobacter cloacae and Erwinia herbicola, that thrive. In the brine-vegetable mixture, these bacteria use up all the oxygen present and make the brine into an anaerobic (oxygen free) environment. Once all the oxygen is used up by the stage one microbes, and the brine is a nice anaerobic environment, we enter into stage two.
Stage Two: The second stage begins about three days past the start of fermentation. At this time the stage one bacteria have died off, and Leuconostoc species of bacteria populate. Leuconostoc species are lactic acid bacteria that tolerate salt and acid. They are Gram-positive cocci shaped, heterolactic fermenters (heterolactic means that they produce two different acids.) Lactic acid, ethanol and carbon dioxide along with small amounts of acetic acid and glycerol are produced when these bacteria thrive. This is the bubbly stage! At the time for stage two you want to look for bubbles from the carbon dioxide being produced (be sure to burp the fermentation jar during this stage). In stage two the environment becomes more acidic, leading us into stage three.
Stage Three: This stage begins after about six to eight days from the start of fermentation. The bacterial population mostly consists of Lactobacillus species in stage three. Lactobacillus species are salt-tolerant, acid-tolerant, homolactic fermenters. They are considered homolactic fermenters because the one main product from their fermentation of plant sugar is lactic acid. Their metabolism of plant sugar into lactic acid results in a acidic pH of about 3.1 - 3.7. The lactic acid produced in this stage is actually what preserves the ferments. Once stage three is reached you want to give your ferments time to be in stage three for a bit, so that the lactic acid bacteria have adequate time to produce their wonderful preserving substance! We always wait about two weeks after this stage is reached, because that time yields a safe pH and a perfectly pleasant sour taste. It is okay to vary this time just a bit though. It is fine to taste test, refrigerate and eat at about 12 days past reaching stage three, (which would be around three weeks total time).
To reach stage three and to prevent unwanted microbes in your ferments, vegetables MUST stay in an anaerobic environment; you must keep the produce you are fermenting submerged in the anoxic brine created in stage one. Using a fermentation weight is best to accomplish this. You also should remember to keep your ferments at a favorable temperature of about 70-80 degrees F and not in the sunlight. Lastly a steadily decreasing pH is needed, ph strips are great for checking the progress of pH as your ferments move through the stages.
Let us all recall that not everything you find on Google and Wikipedia is true. It's important when finding information online to also learn about the person providing that information, and what makes them qualified to do so. Ask yourself questions like: What is the author's level of education in this subject? What experiences qualify the author to provide safe and accurate information?
Fermented vegetables is an up and coming area in the food scene, and it is more than just trendy. Thanks to science, there's lot's of research and evidence on the positive effect of probiotics and fermented vegetables for gut health. This means that fermented foods are here to stay. In order for fermented foods to remain classified as healthy and viewed in a good light, fermentation needs to be done properly. This starts with the educators of at home fermentation.
Again, let us focus on the microbes when it comes to microbial made foods.
If you are interested in safely fermenting foods at home, visit our blog index for detailed step by step recipes.
Peace, Love and Probiotics
*Footnote: Bacteria, yeast, viruses, and molds are all vastly different types of organisms and these words cannot be used interchangeably. Using the word yeast and the word bacteria interchangeably is like using the word human and the word cactus interchangeably.