HOW DOES LACTO-FERMENTATION WORK?
So, how does it work? A brine is created by adding salt to vegetables which release their juices, or by dissolving salt in water. The vegetables are submerged under the salty brine, in an anaerobic (no oxygen) environment, so any microbes which spoil food, or those which can cause foodborne illness, cannot survive.
Lactic Acid bacteria (LAB) are naturally present on the vegetables, and they can tolerate and survive in the salty, anaerobic conditions. The LAB feed off the sugars in the vegetables, convert it to lactic acid, which lowers the pH to create an acidic environment, which safely preserves the food. The LAB are the good bacteria, commonly known as ‘probiotics’.
WHAT CAN YOU LACTO-FERMENT?
You can lacto-ferment a number of foods, including:
- vegetables (like cucumbers, cabbage, carrot, beans, garlic)
- salsas, sauces and other condiments
- dairy (yoghurt and cheese)
- fruit (lacto-fermenting fruit may be more complicated)
This guide covers the essentials about lacto-fermenting vegetables, as that is a great place for beginner’s to start.
Note, there are other types of fermented or ‘cultured food’, such as sourdough, vinegars, beer and wine, kefirs and kombuchas, cured meats etc. which use different microbes.
DOES LACTO-FERMENTATION INVOLVE LACTOSE/ DAIRY?
A fairly common misconception related to the term ‘lacto’ often occurs, but ‘Lacto’ fermenting does not mean that dairy has to be involved (although you can find LABs in fermented dairy, i.e. yoghurt). It refers to the Lactobacillus lactic acid bacterias required for the process.
ADVANTAGES TO LACTO-FERMENTATION
- May increase biodiversity in gut microbiota, and improve levels of ‘good bacteria’ strains of Lactobacillus bacteria
- May include making some foods more digestible, as lacto-fermenting breaks down indigestible elements, and also increases the bioavailability of enzymes, vitamins & minerals in the food
- Easy to moderate difficulty level
- Requires less equipment and energy/ water use than other common preserving methods (i.e. bottling or dehydrating)
The collection and diversity of microorganisms (known as your microbiota) in your large intestine can affect your digestion, immunity and mood, so why wouldn’t we want to increase diversity and build numbers of the good guys?! Read more here in 10% Human by Alanna Collen. You can also read more about how the good bacteria make it to your large intestine in this article.
DISADVANTAGES TO LACTO-FERMENTATION
- The sour/ tangy/ salty taste and strong funky fermenting smells may be not to your liking
- Takes space on your kitchen bench for jars of ferments for weeks at a time, and then room in your fridge (or a suitable cool place) to store them once they have reached the level of fermentation you desire
- Requires chlorine free water, and iodine free salt (which may not be as accessible)
- Fermented foods may not last as long as bottled/ canned preserves. Whilst they can be boiling water bathed in jars, this processing/ heat treating in a boiling water bath kills off the good microbes (same reason why it isn’t recommended to heat/ cook your fermented veges, or use them in hot foods above 42°C)
- Need space to store the equipment and jars of ferments
IS LACTO-FERMENTATION SAFE? HOW CAN WE TELL IF IT IS SAFE TO EAT?
As with any form of food preservation, the key to safety is understanding the science behind the processes, ensuring you follow the steps you need to take, and observe for variables which may occur.
You cannot rely on what it looks like, or how it smells, or tastes, to determine if it is ‘safe’. Lacto-fermented foods smell and taste funky (and many food poisoning bacteria create no smell anyway). If you are unsure what your end result should look, smell and taste like, see if you can buy a jar of lacto-fermented veges from your local health food shop or organic grocer (or even online). Or ask a fermenting friend to give you a taste test! That can give you some confidence to know if your own lacto-fermentation has done the ‘right thing’.
By creating an anaerobic environment, using non-iodine salt (and non-chlorinated water if creating a wet brine), using fresh organic vegetables, keeping it at around 20’C, and watching for the bubbling to occur, you are doing everything you can to support the lacto-fermentation process.
A NOTE ON CLOSTRIDIUM BOTULINUM
Note, one of the most serious foodborne illness microorganisms is Clostridium botulinum, a soil-borne bacteria which produces toxins that can cause botulism, a potentially fatal paralytic illness. Unlike many other food microorganisms which die without oxygen, C.Botulinum produces spores which survive in anaerobic (low to no oxygen) conditions. The spores are activated and toxins are produced in moist, low-acid, oxygen free environments, at an ambient temperature.
So to ensure C.Botulinum spores cannot survive or grow when preserving, there are a few safety rules to follow, but in the case of lacto-fermentation where we generally are using low acid produce, we need to create a high lactic acid environment (with a pH less than 4.6) that can penetrate the produce. Whilst we wait for the LAB to start producing lactic acid that can change the pH, we rely on the salt brine to inhibit C. Botulinum.
The following ‘timeline’ depends on the conditions/ warmth (warmer = faster, cooler = slower), the produce and the amount of salt that you use. The process occurs approximately like this:
Day 0 – Prepare your vegetables and brine, and place in suitable containers, submerging the prepped veges under the brine. Locate the containers in a place that has temperatures 15 to 20°C and is away from direct sunlight (or wrap glass containers in a tea towel), where you can keep an eye on the process. Note, cooler temperatures than 10°C and the ferment will take longer or not happen, but any warmer, above 22°C, and it may happen too quickly and possibly become smushy.
Day 1 to 3 – No visible action, but the anaerobic environment deprives certain bad aerobic bacterias of oxygen, so they are diminished; the anaerobic good bacteria grow and the pH starts to change
Day 4 to 8 – Bubbling starts as carbon dioxide is produced; Lactic acid levels increase to 2.5% and pH level decreases to as low as 3.4
Day 8 to 10 – Bubbling slows or stops (lacto-fermenting is still taking place, but different LAB dominate who don’t produce carbon dioxide); Taste now (using a clean fork, don’t double dip) and see if it is ‘sour’ enough. If not, leave to ferment for a couple more days, and taste again. Note, some people may ferment at room temperature for weeks to achieve the sourness/ flavour they desire.
Once you are happy with the flavour/ sourness, remove the airlock and plug the valve (if you are using Pickl-it jars) and transfer the container to cool place or fridge (this will slow the fermentation process). Some people decant their fermented vegetables into smaller jars to store in the fridge.
WHAT GOOD BACTERIA ARE INVOLVED DURING THIS PROCESS?
“There is a sequence of lactic acid bacteria that grow: Leuconostoc mesenteriodes grows first, producing lactic acid, acetic acid and carbon dioxide. Then Lactobacillus brevis grows, producing more acid. Finally Lactobacillus planarum grows, producing still more lactic acid and lowering the pH to below 4.0 At this pH and under anaerobic conditions, the cabbage and other vegetables will be preserved for long periods of time.” Source
For more information on the scientific processes occurring, read this great article on Pickl-It.
You can lacto-ferment vegetables using basic equipment, such as Mason jars or flip-top lid glass jars you already have, and ziplock bags filled with brine to submerge the vegetables. However, I think it is worth the investment to buy specific fermenting equipment.
You don’t have to buy super pricey crocks which cost hundreds of dollars, there are certainly other options. In fact, since I started fermenting, there are loads more affordable and accessible options available (I had to get my Pickl-It jars/ lids shipped from the USA as no one here sold them or anything like them at the time in 2011). You can just start with one kit, or one lid to adapt your existing preserving jars.
Note, avoid metal containers (it may react with the acid), but ceramic and glass are good (possibly plastic, your choice, but it may leach toxins). Metal utensils to make the lacto-ferment are OK.
WEIGHTS/ SUBMERGING OPTIONS
To keep the vegetables, herbs and spices submerged under the brine, and in an anaerobic environment, you can try these options:
- ziplock bag filled with brine, or with ceramic blind baking weights
- smaller jar filled with water that fits into the mouth of a bigger jar that you are fermenting in
- glass weights – I use Dunk’R’s which came with my Pickl-It kit
- using a piece of cabbage leaf wedged into the jar, or ‘woven’ carrot/ vege peelings, pushing the other vegetables under the brine
‘OPEN’ VESSEL/ JARS
What is it? Using a jar without a lid or a casserole dish, or an open crock, with a plate, dish or above options to submerge the vegetables under the brine, with a cheesecloth or tea towel cover to keep bugs away. Like this Cheapo Jar Method or Fermenting Vegetables in a Mason Jar
Benefits Affordable, using something you may already have
Challenges More exposure to air/ oxygen, which may mean more chance of Kahm yeast/ moulds/ aerobic bacteria growing on the surface. The LAB are facultative anaerobes, which means they can still do their thing, even if some oxygen is present. Unfortunately this means the moulds/ yeasts can too!
JARS WITH FLIP TOP LIDS
What is it? flip-top lid glass jars like Bormioli Rocco Fido, which have the lid on a wire bale, a rubber seal, and using an option above to submerge your vegetables under the brine
Benefits you may have these already, or can source them secondhand or cheaply; less exposure to air than an ‘open vessel’
Challenges requires ‘burping’ to allow release of the gas build up, or they could potentially break
ONE WAY VALVE/ AIRLOCK LIDS or INSERTS
What is it? You can buy lids or inserts with one-way valves or airlocks, that can retrofit your existing preserving jars, for a reasonable price. You still need to submerge the vegetables under the brine. Some examples:
- Mason Jar Fermenting Lids
- Fowlers Vacola Fermenting Lids
- Weck Jar fermenting lids
- Pickle Pipe (waterless fermentation air lock for wide mouth mason jars)
Benefits Add to existing gear you already have, affordable and easy to store; can suit small batches
Challenges Not as cheap as buying nothing!
What is it? fermenting crocks, are usually larger ceramic containers which have a lid and ‘water grove’ or channel around the rim that you fill with water, to create a water seal that carbon dioxide can escape out of, but oxygen cannot enter the crock. You still need to submerge the vegetables under the brine.
Benefits Dark vessel protected from light; good for large batches
Challenges May be heavy, may be expensive; Decant vegetables after fermenting into smaller jars for storage. You may need to top up the water grove/ moat.
What is it? Jars that come with lids and existing airlocks/ one way valves. You still need to submerge the vegetables under the brine.
I do my fermenting in Pickl-It jars, which have a one-way water lock valve in the lid. I also had and bought Bormioli Rocco Fido jars in different sizes (i.e. 250ml, 500ml, 1000ml, 2.1L, 3L for different sized batches), and can transfer the Pickl-It lids between them (after fermenting is finished, I put a normal flip-top back on from another jar then put the jar of ferments in the fridge, then I can wash the Pickl-It lid, fit it to that jar without a lid, ready to use again). Or the Pickl-It jars come with rubber stoppers to insert into the valve so you can remove the airlock before cold storage.
Pickl-It are now available in Australia at Emporio Organico.
Benefits anaerobic system; easy to use; and able to buy different sized Fido jars & interchange the lids with Pickl-It jars to suit different sized batches; if herbs/ spices/ pieces of vegetables float to the top of the brine, it doesn’t matter so much, as the environment is anaerobic
Challenges the cost may be prohibitive; need somewhere to store them between uses; need to keep an eye on water level in the airlock
- tea towel/ cover to wrap around glass containers
- knives or mandolin for cutting finely
- measuring spoons
- scale for weighing salt
- jug & whisk to dissolve salt into brine
- tool for pounding (when making sauerkaut)
DO I HAVE TO STERILISE MY EQUIPMENT FIRST?
No, you don’t have to pre-sterilise your container or equipment. Just wash in hot soapy water and rinse, or use your dishwasher (if applicable). The salted anaerobic environment will stop any possible remaining bacteria from growing.
VEGETABLES, HERBS + SPICES
- Use organic vegetables to make sure you have good Lactic Acid Bacteria (LAB) available (your ferment will still work even when using conventional treated produce, but I prefer to use home grown or locally sourced organic vegetables, because who wouldn’t!)
- Don’t peel or remove outer layers – we want the LAB that are on the outside – if there is visible dirt, wash it off
- Use fresh as possible – only use vegetables that are fresh and show no signs of decay/ mould etc
- Purple and brightly coloured carrots/ cabbage etc will change the colour of the rest of the vegetables that you use
- You can use garlic – any antimicrobial properties will not ruin the lacto-fermenting process (Note, lacto-fermentation of garlic cloves can sometimes turn them blueish-green, but that’s OK)
- You can use black peppercorns, juniper berries, caraway seed, fennel seed, chilli powder, dill seed, finely grated tumeric and ginger etc. but be warned that whilst some flavours may mellow, the flavours from herbs and spices can become more intense as they penetrate the other ingredients
- You use herbs and stems/ roots from herbs – check for bugs first, if using home grown herbs!
- You can use grape or oak leaves to help keep cucumber pickles crunchy, because of the tannins in them
- Use water without chlorine – we have a stoneware water purifier with a filter that removes fluoride and chlorine from our tap water
- You can use tapwater that has been left in an open container on your kitchen bench for 24 hours to reduce the chlorine levels by evaporation, or by boiling it for 15 to 20 minutes
- You could use filtered rainwater
- You could use bottled water in a pinch
Fine table/ cooking salts are suitable to lacto-ferment with, providing they have no iodine added. The iodine has antimicrobial properties, and could affect the development of our LAB/ good bacteria. Also check there are no other additives, like anti-caking agents. For great results (and possible extra minerals) you can use:
- fine sea salt (i.e. Australian or Celtic sea salt)
- fine rock salt (i.e. Himalayan salt)
- other natural fine salt (i.e. Murray River salt flakes)
If you have coarser grade salt on hand, just remember that there is less salt by volume since there is more room for air between the grains. In this case, it will be better to weigh the salt to determine the grams, rather than measuring by volume. See Brine section.
SHOULD I USE WHEY, OR A STARTER CULTURE?
The Lactic Acid Bacteria (LAB) come from the soil and are naturally present on the vegetables, which is why using organic and fresh produce is important when lacto-fermenting (and well, anytime). You do not need to use whey (from yoghurt or cheese making), starter culture, or even brine/ liquid from a previous batch of LF veges. However, some people might use these to introduce LAB. They do this because:
- they are not using salt, or are using less salt, and want to ensure the ‘good bacteria’ grow and produce lactic acid quickly
- they want a ‘foolproof’ result, knowing the ‘right’ bacteria have been added
- they’ve been told to, or have read in certain well known books to do so
The problems with doing this can include:
- LAB from dairy are not the same strains that will thrive on and ferment vegetables
- You may skip stages of the lacto-fermenting process, as you’ve added ‘end-stage’ bacteria, and the early and middle stage LAB may not get a chance to do their equally important thing
- The introduced LAB strains becoming dominant, and you may miss out on the ‘wild’ LAB that are naturally present on the vegetables, and therefore the biodiversity available for your gut
What is brine? Why do we use it?
Brine is salty water (high concentrations of sodium chloride in water). Although some lacto-fermenting is done without salt, I use a brine as I like the salty flavour, and I feel it is a safer way to lacto-ferment vegetables. The high salt levels absorb moisture from the food, and deny the food spoiling/ poisoning microorganisms the aqueous solution they need, killing them and inhibiting their growth, until the LAB good bacteria produce enough lactic acid (which creates an acidic environment, which is also inhospitable to the bad microbes).
Salt also helps the vegetables retain their crunch, as it helps harden the pectin in the cell walls. (Tannins in oak or grape leaves are also used for this purpose, and definitely make cucumber dill pickles retain their crunch! Don’t forget to cut off the blossom ends too.)
HOW MUCH SALT SHOULD WE USE?
You need a brine between 2% up to 10%. Too little salt and you are at risk of the bad bacteria growing. If you use too much salt, instead of lacto-fermenting, you may actually be ‘salt preserving’, which isn’t necessarily bad, you just miss the good microbes and may also end up with a product too salty to eat!
The more salt you use, the slower the fermentation will be, and the sourer (more acidic) the end result will be. The less salt you use, the faster fermentation will be, and less sour result.
Every salt has a different weight depending on its grind, density and moisture content. 1 tablespoon could weigh 10gm, but another could weigh 16gms! Therefore, some people prefer to weigh their salt, instead of measuring by volume (using cooking tablespoons), as it is considered more accurate. Also, in Australia, our cooking tablespoons hold about 20mls or 4 teaspoons, but in the USA and UK, theirs hold about 15mls, or 3 teaspoons.
DRY BRINE (AKA SELF BRINE)
We can create a Dry Brine by adding salt to vegetables (such as cabbage when making sauerkraut, AKA a ‘self brine’) and massaging and pounding it in, causing the juices from the vegetable to be released (from osmosis and as the cell walls breaks down) and mix with the salt.
- The general ratio is 1 tablespoon (17gm) of salt for every kilogram of vegetables.
We can create a Wet Brine by dissolving salt in water and create a brine to pour over vegetables (such as cucumbers, when making dilly pickles).
- For every tablespoon of salt, 17gm, you add to that litre of water, increases the brine by approximately 1.8% (see note)
- To make a 3.6% brine, use 2 tablespoons (34gm) per litre of water. If you are fermenting in cooler weather or conditions, or fermenting harder vegetables (i.e. carrots, green beans, beetroots) you may use a lower brine, like 3.6% brine. This is considered ‘half sour’ when fermenting cucumber pickles.
- For a 5.4% brine, use 3 tablespoons (51gm) per litre of water. If you are fermenting in warmer weather, or using higher water content vegetables (i.e. cucumbers) consider using a higher percentage brine, like 5.4%, which will help control the ferment and retain crunch. This is ‘full sour’ when fermenting cucumber pickles.
Note, the wet brine measurements are taken from Wild Fermentation p.51, where 1 tablespoon of 17gm salt is added into a quart of water, which is 946mls, about 1.79%. Of course, a litre is 1000mls, so the % don’t quite calculate, but I presume Sandor called it ‘close enough’ when converting the measurements.
NO BUBBLING TROUBLESHOOTING
Don’t panic, some lacto-fermenting vegetables will not bubble as much as others, like condiments which are thicker, than cucumber pickles in a brine. Or you may not notice the bubbles escaping if they are tiny, or continually being released. Look closer, or gently agitate the container to see if bubbles do escape.
If your vegetables do not seem to have started bubbling during the lacto-fermentation process, troubleshoot by considering:
- Did you use non-iodine salt? Did you use between 2 to 10% brine?
- Did you use non-chlorinated water?
- Did you use organic, fresh vegetables?
- Do you have it located in a warm temperature (15 to 20°C)?
- Are you using a container that ensures an anaerobic environment?
Once you have prepped and commenced fermenting of your vegetables, the only thing you can really change is the temperature, by moving the container to a warmer spot. Otherwise, you may have to start again if one of the other elements is the issue.
HELP, MY LACTO-FERMENT SEEMS TO BE GROWING MOULD!
A white to cream coloured film on top of your lacto-fermenting vegetable brine might be Kahm yeast, a harmless aerobic yeast. Anything fuzzy, blue, green or darker in colour, thick or emerging above the brine level, is more likely to be mould.
Whilst many people will scrape or remove the mould and continue fermenting, or eating the lacto-fermented vegetables, but I do not think it is worth the risk. Not only are moulds potentially bad for you, some people have allergic reactions to the moulds, and if conditions allowed an aerobic mould to grow, it may also have allowed aerobic food poisoning microbes to grow.
Avoid mould growing in future ferments by using a container with an one-way valve or airlock to ensure anaerobic onditions, and making sure you keep the vegetables submerged under the brine. Pack the vegetables in and use a container in which ‘headspace’ is minimised.
How do we eat lacto-fermented veges?
You can eat them as a condiment, on top of breakfast, lunch or dinner! They will lose their good microbial benefits if you cook them, or expose them to hot foods. I eat mine with my veges and fried egg for breakfast. I love them in a salad wrap. I plonk some of top of a curry or soup before eating.
Start slow with the amount that you consume, building up over time, as you may experience ‘die off’ (of all the bad bacteria built up in your gut) when starting out with cultured/ fermented foods. ‘Die off’ may be flu-like symptoms. This article explains a bit more.
STORING YOUR LACTO-FERMENTED Veges
Label, date and store your jars in a cool, dry place with temperatures between 0 to 10° C. This is likely to be your fridge, but it may be a root cellar or pantry. If you freeze them, the good bacteria may revive upon being defrosted, or may not, and the vegetables will probably go mushy anyway.
HOW LONG DO THEY LAST?
It depends on many factors, like what vegetables you fermented, how sour you like it, if it has gone too soft/ mushy etc. Some people store their lacto-fermented vegetables for months, even eating them after a year. I generally eat mine up within a couple of months after being moved to cold storage, but I then I purposely make smaller batches so that they don’t linger in the fridge for months.
- Pickl-It – What is Lacto-fermentation? and What are Lactic Acid bacteria?
- Cultures for Health – Busting Lacto-Fermentation Myths plus How Time and Temperature Affect Vegetable Fermentation
- Erica from Northwest Edible Life – How Much Salt plus a great recipe for Lacto-fermented Salsa
- Phickle – Dill Pickles recipe and tips for best cucumber pickles
- Milkwood Permaculture – Making simple sauerkraut with whatever greens you’ve got
Clean your hands and kitchen bench. Gather equipment and materials. Based on the recipe, or your choice of brine %, dissolve salt in water
Measure your herbs and spices, as per your recipe. Add smaller pieces to the bottom of the jar so they are less likely to float above the brine
Julienne or shred your veges – this works well to retain some crunch, compared to grating
Cut into bite sized pieces, which are easier to remove in small portions when it comes time to eat the fermented veges
Pack vegetables into the jar. If using different types, you can mix them up before packing in to ensure you get a mix when you scoop them out to eat them once finished, or do them in layers.
Do not overfill the container, as brine and vegetable juice will expand into the airlock, but try to choose containers where there will be minimal headspace.
Wedge a piece of cabbage or strips of vegetables on top of the vegetables, pressing them down, to help submerge the chopped veges and herbs/ spices once the brine is added.
Stir to make sure your brine has dissolved. Pour over the vegetables. Gently agitate the container to make sure the brine has filled in gaps/ spaces, and top up if needed.
Add a glass weight on top of the cabbage leaf or strips of vegetables. If you have used all your brine, but it is not covering the vegetables and glass weight, make up another small amount of brine using the same percentage to top it up with.
Add the lid and clamp it on, then fit the airlock in to the rubber valve area. Top up the airlock to the line, using brine or filtered water.
Place in a location which gets consistent temperatures around 15 to 22°C, away from direct sunlight (or cover with a tea towel) but where you can watch for bubbling to start.
Once bubbling has stopped, use a clean fork to remove a sample to taste. If it isn’t to your liking yet, continue fermenting & taste in a couple of days. When it tastes sour enough, remove the airlock & plug the valve, or change out the lid for a normal Fido lid. Transfer to cold storage/ fridge.
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