Easy Homemade Ferments: Plant-Based Yogurt, Pickles, and More

For lacto-fermented vegetables, use 2% salt by weight of vegetables, hold the jar at 21 to 24 °C, and allow three to four weeks rather than one. For soy yoghurt, allow 8 to 12 hours at around 42 °C with a starter, using a soy drink that contains enough protein to set. For vinegar pickles, use vinegar of 5% acidity and keep them in the fridge permanently, because they are not preserves.

Three things these preparations do not do, despite what they are regularly credited with. They do not make usable vitamin B12: tempeh contains 0.019 micrograms per 100 grams according to the French ANSES Ciqual table, less than 1% of the Swiss reference value of 2.5 micrograms. They are not probiotics in any regulatory sense: the word appears nowhere in the Swiss ordinance on food information, and no health claim of that kind is listed in its Annex 14. And they do not lighten your salt load: drained sauerkraut carries 505 milligrams of sodium per 100 grams and vinegar gherkins 689, while adults in Switzerland already eat 8.7 grams of salt a day against the 5 grams recommended by the WHO.

Everything else they do is more than enough to justify the jar.

Two families that get confused constantly

Lacto-fermentation and vinegar pickling produce similar flavours through opposite mechanisms, and mixing them up costs whole batches.

In a lacto-fermentation, the lactic acid bacteria already sitting on the vegetable do the work. They convert the plant’s own sugars into lactic acid, acidity climbs steadily, and the environment eventually turns hostile to almost everything else. You add no micro-organisms at all: you create conditions in which the ones already present take over, essentially by salting and by excluding oxygen. One practical consequence surprises people. You should not sterilise the jar by boiling it. The National Center for Home Food Preservation asks you to wash the container, the plate and the weights in hot soapy water and rinse well with very hot water. Nothing more. A sterile jar does not ferment better, and the useful flora comes from the cabbage anyway.

In a vinegar pickle, nothing ferments. You pour an already acidic liquid over vegetables to preserve them. The acidity is not built up over time, it arrives at the start, and its value depends entirely on what you put in the pan. The NCHFP is blunt here: the level of acidity in a pickled product matters as much for safety as for taste, you must not alter the vinegar, food and water proportions, and you must not use vinegar of unknown acidity, because a minimum uniform level of acid throughout the mixture is what prevents Clostridium botulinum from growing. Vinegar labelled at 5% acidity is the reference.

So these are two different safety logics. One rests on time and salt, the other on chemistry fixed from the first minute. The guide to homemade lacto-fermentation safety goes deeper into the first case.

Plant-based yoghurt: the method, and what it costs you in calcium

Homemade soy yoghurt is the simplest preparation here, and the one whose nutritional consequences most often pass unnoticed.

What you need

One litre of plain unsweetened soy drink, a sachet of yoghurt starter culture or a shop-bought plant yoghurt with live cultures to inoculate, clean glass jars, and a stable heat source.

The base matters more than the equipment. A soy drink supplies roughly 3.3 grams of protein per 100 grams according to Ciqual, enough to form a gel once acidification makes the proteins coagulate. Almond and rice drinks contain a fraction of that, and they often lack the fermentable sugar the bacteria feed on as well. They do not set, or they set because the manufacturer added thickeners. This is not a technique problem.

The method

Heat the soy drink to about 42 °C and no more. Yoghurt cultures work at roughly 42 to 45 °C, and a clearly higher temperature kills them. A kitchen thermometer settles the question better than a fingertip, because the gap between warm and hot covers exactly the range where everything is decided.

Take the pan off the heat, stir the starter in gently, and do not whisk: foam creates air pockets that stop the set from being even. Pour into the jars, cover, and hold at 42 °C for 8 to 12 hours. A yoghurt maker does this unattended; an oven on its lowest setting with the light on works too, provided you have checked the real temperature once.

The yoghurt is ready when it has set and turned clearly tart. The longer it ferments, the firmer and sharper it gets. Then refrigerate: at 0 to 5 °C, the range the UK Food Standards Agency gives for a correctly set fridge, it thickens a little more and keeps for about a week.

Calcium, the question nobody asks

A plain unfortified soy drink contains 12 milligrams of calcium per 100 grams. The same drink fortified with calcium contains 98. A shop-bought plain fortified fermented soy dessert contains 120. The Swiss nutrient reference value for calcium is 800 milligrams a day.

Put differently, if you replace fortified plant yoghurts with homemade ones based on an unfortified drink, you lose essentially the entire calcium contribution of that food without gaining anything in exchange. That is not a reason to stop, it is a reason to choose the base deliberately: start from a calcium-fortified soy drink, or make it up elsewhere. The same starter cultures work perfectly well on a fortified drink.

The same holds for vitamin B12, which is not in soy and which fermentation does not create. The article on choosing vegan probiotics covers what separates a fortified product from a merely fermented one, and the guide to plant yoghurt without a yoghurt maker deals with the equipment question.

Lacto-fermented vegetables: the four numbers that decide everything

Salt

Twenty grams of salt per kilo of vegetables, which is 2%. That proportion is not a seasoning setting. It selects lactic acid bacteria, which tolerate it, against much of the competing flora, which does not. The NCHFP states it plainly for fermented products: do not attempt to make sauerkraut or fermented pickles by cutting back on the salt required. The rule is different for vinegar pickles, where salt can be reduced or left out with no safety consequence, at the price of noticeably poorer texture and flavour.

Iodised salt deserves a note, because you often read that it should be avoided. The NCHFP’s reservation is cosmetic: anti-caking agents added to some salts cloud the brine, and iodised salt can darken pickles. That is an appearance issue, not a safety or fermentation issue. In Switzerland, iodised salt supplies 51% of the population’s iodine intake according to the Federal Food Safety and Veterinary Office, in a country whose soils hold very little of it. If you salt lightly elsewhere, keeping iodised salt for everyday cooking and reserving non-iodised pickling salt for the jars is a reasonable trade-off rather than an obligation.

The container

The NCHFP counts one gallon of container per five pounds of fresh vegetables, roughly 3.8 litres for 2.3 kilos: about 1.5 litres of container per kilo of vegetables. That headroom is not wasted space, it absorbs the rising brine and the foam that forms.

The vegetables must stay submerged 2.5 to 5 centimetres below the brine for the whole fermentation. A weight is therefore essential: a plate slightly smaller than the opening, held down by sealed jars of water, or a well-sealed food bag filled with salted water. Anything that pokes above the brine grows mould. It really is that simple.

Temperature

This is the number most often wrong in circulating recipes. The USDA recommends 21 to 24 °C for sauerkraut. In that range fermentation completes in three to four weeks. At 15 to 18 °C, allow five to six weeks. Below 15 °C the cabbage may not ferment at all. Above 24 °C it goes soft. For fermented cucumbers the markers are the same, with a warning to avoid exceeding 27 °C or the pickles turn soft during fermentation.

A quoted range of 20 to 30 °C, which appears everywhere, therefore sends half your batches into the softening zone.

Time

Three to four weeks for sauerkraut or fermented cucumbers at 21-24 °C, not seven to ten days. After a week the vegetable is tangy and edible, but fermentation is not finished and acidification has not run its course. The most reliable end signal is bubbling stopping. If you use jars as a weight rather than a brine-filled bag, check two or three times a week and skim any scum as it appears.

Once fermentation is complete, sauerkraut keeps for several months in the fridge in a tightly covered container. Fermented cucumbers keep four to six months refrigerated in their original container, provided surface scum and moulds are removed regularly.

The detail that saves cucumbers

Cut off and discard a 1.6 millimetre slice from the blossom end of every cucumber. That end carries an enzyme that softens pickles. Leave 6 millimetres of stem attached. And start fermentation within 24 hours of harvest: beyond that, the NCHFP links the delay to hollow and shrivelled pickles. Hollow cucumbers float during washing, so set them aside for a relish.

Quick vinegar pickles: a recipe you do not improvise

For 500 grams of firm vegetables cut into rounds or sticks, a brine of 250 millilitres of 5% acidity vinegar and 250 millilitres of water, a tablespoon of salt, a tablespoon of sugar if you want to soften the edge, and whole spices rather than ground ones, which cloud less.

Bring the brine to the boil, pour it hot over the vegetables packed into a clean jar, cover them completely, seal, let it cool to room temperature and refrigerate. They are edible after 24 hours and good for several weeks, cold.

Two points to watch. First, the vinegar-to-water ratio is a safety parameter, not a preference. Diluting further, or using an artisanal vinegar of unknown acidity, breaks the acidity guarantee. Second, these jars are not preserves. A lid that dips as the contents cool produces a vacuum, not sterilisation. They live in the fridge, full stop. Express pickles in 24 hours follow exactly this logic, and turning peelings into pickles suits the method particularly well.

The salt these jars add to your day

Nobody counts the salt in their own preserves, and it is the most measurable blind spot in home fermentation.

One hundred grams of drained sauerkraut supply 505 milligrams of sodium according to Ciqual, about 1.3 grams of salt. One hundred grams of vinegar gherkins reach 689 milligrams of sodium, about 1.7 grams of salt. Miso, routinely presented as a health ferment, sits at 3340 milligrams of sodium per 100 grams, which makes it a condiment and nothing else.

Against that: the Swiss survey run between March 2022 and August 2023 with 863 participants puts average adult consumption at 8.7 grams of salt a day, roughly 75% above the recommended 5 grams. The WHO links excess salt directly to raised blood pressure and cardiovascular risk.

A portion of sauerkraut twice a week changes nothing in that picture. A diet where fermented vegetables replace fresh ones at every meal does. The difference is frequency and what the jar displaces, not whether it was made at home. The guide to seasoning without salt covers the levers that compensate elsewhere, and the article on miso and tamari puts numbers on what those condiments cost in salt.

Vitamins: what the micro-organisms actually make

A systematic review published in Frontiers in Nutrition in 2025 went through the human studies only, from 1970 to 2024. Its conclusion is narrower than the usual promise.

Certain micro-organisms, including Bacillus subtilis, Propionibacterium freudenreichii and some lactic acid bacteria, do raise the levels of vitamins K2, B2, B9 and B12 in fermented foods. In humans, two effects are documented: improved folate bioavailability after eating Camembert naturally rich in B9, and improved vitamin K2 status in several studies on natto, a Japanese fermented soybean product. For the other B vitamins the evidence is limited or inconsistent, and for the remaining vitamins there is no human evidence at all. The authors conclude that well-controlled large-scale human trials are still missing before fermented foods can be treated as a strategy for vitamin status.

The B12 case deserves numbers, because it concerns vegetarians and vegans directly. Ciqual’s tempeh entry contains 0.019 micrograms of B12 per 100 grams. The Swiss reference value is 2.5 micrograms a day. You would have to eat more than 13 kilos to cover a single day. The unfortified fermented soy desserts in Ciqual come in at zero or below the detection threshold. Home fermentation of vegetables or soy does not produce B12 you can rely on. A fortified food or a supplement remains the only dependable route.

Vitamin K1, on the other hand, is genuinely there: 42.8 micrograms per 100 grams of vinegar gherkins, 31 for sauerkraut, against a reference value of 75 micrograms a day. The NHS puts adult requirements at roughly 1 microgram per kilo of body weight per day. That content is irrelevant for most people; it matters for anyone taking a vitamin K antagonist anticoagulant, not because these foods must be avoided but because consistency of intake is what counts. A steady habit is easier to balance than three jars a week followed by three weeks of none, and the question belongs in a conversation with the team managing the treatment.

Probiotics: why the word means little on a homemade jar

The NHS is direct about this: probiotics are live bacteria and yeasts promoted as beneficial, there is some evidence they help in certain cases such as easing some symptoms of irritable bowel syndrome, but little evidence supports most of the health claims made about them. Because they are classed as food rather than medicine, we cannot always be sure the product contains the bacteria stated on the label, that it contains enough of them to have an effect, or that they survive long enough to reach the gut. The NHS adds that there is likely to be a huge difference between the pharmaceutical-grade strains that show promise in clinical trials and the yoghurts and supplements sold in shops.

On the Swiss side the point is regulatory: the ordinance on food information permits only the health claims listed in its Annex 14, and any other claim requires authorisation from the Federal Food Safety and Veterinary Office. The word “probiotic” does not appear in it. A homemade jar cannot claim that status, and neither can a commercial product.

None of this means fermented foods do nothing. The randomised trial published in Cell in 2021 followed two groups of 18 adults for seventeen weeks, one on a high-fibre plant diet, the other on a high-fermented-food diet. The fermented food arm showed steadily increasing microbiota diversity and falling inflammatory markers. That is the strongest human result available, and it comes with limits: eighteen people per arm, a whole food category tested together rather than any single product, and daily amounts well above an occasionally opened jar. The review published in Advances in Nutrition in 2025 lands in a similar place: consistent protective associations, significant methodological limitations, and a need for standardised product characterisation before dietary recommendations can follow.

What you get from a jar of lacto-fermented vegetables is unknown strains in unknown quantities. It may well be doing you good. It simply is not measurable, and it should not feature in any health decision.

Biogenic amines: the one real quantitative limit

Biogenic amines are decarboxylation products of amino acids formed during microbial fermentation. They are unavoidable in fermented foods, and a review published in Heliyon in 2024 collected the measured levels.

For sauerkraut: 37 milligrams of histamine and 206 milligrams of tyramine per kilo. For kimchi: 947 milligrams of histamine and 358 of tyramine per kilo. Fermented vegetables generally sit between the two, with considerable variability depending on the raw material and how the fermentation ran.

The thresholds. In a healthy person, no adverse effects are expected from a histamine exposure of 25 to 50 milligrams per meal. In someone with histamine intolerance, 5 to 10 milligrams is sometimes enough to trigger marked symptoms. Alcohol amplifies the effect by inhibiting the enzymes that break these amines down. For tyramine, no toxic threshold is established in healthy humans, but the interaction with monoamine oxidase inhibitors is well documented and can push blood pressure up.

Translated into portions: 100 grams of kimchi carries around 95 milligrams of histamine, above the range where effects can appear even in people who do not know they are sensitive. The same weight of sauerkraut carries under 4. The review published in Critical Reviews in Food Science and Nutrition in 2026 stresses the point that bears most on home cooking: spontaneous fermentation, without a defined starter, is precisely the kind that produces the least predictable accumulation.

In practice this concerns three situations. People with food-triggered migraines. People taking an MAOI. People with documented histamine intolerance. For everyone else it is not a cause for worry, it is one more argument against building a diet around ferments.

Kombucha: what the protocol actually requires

Kombucha is sweetened tea fermented by a symbiotic culture of bacteria and yeast, the SCOBY. The protocol published by the NCHFP supplies the numbers most recipes leave out.

Equipment is washed with soap and water, then sanitised by submersion in water of at least 77 °C for at least 30 seconds. Here, unlike lacto-fermentation, sanitising makes sense: you deliberately inoculate with a SCOBY and starter liquid, and there is no resident flora to protect. The pH of the starter liquid is measured before you begin, with a strip.

Tea is steeped in water at 71-77 °C, the sugar is dissolved afterwards, and the mixture is cooled below 35 °C before the SCOBY goes in. Fermentation runs at 20 to 25 °C for 7 to 10 days under a breathable cover: paper towel, coffee filter or clean cheesecloth held with a rubber band. Once finished, the drink goes into clean bottles, into the fridge, to be used within 30 days.

One NCHFP warning is worth repeating: storing kombucha in airtight containers causes CO2 to accumulate and can lead to an explosion if it is not monitored. Second fermentation in a bottle, the step that makes it fizzy, is exactly the risky situation. Burp one bottle a day, and do not use thin glass.

Nutritionally, a commercial kombucha in the Ciqual table shows 1.45 grams of sugars per 100 grams and 9.5 kilocalories, which makes it a light drink. A homemade one stopped early contains considerably more, since the remaining sugar is precisely what the fermentation has not yet consumed. The full method is in the guide to DIY kombucha without expensive equipment, and the neighbouring drinks in homemade water kefir and ginger beer.

Homemade tempeh: the project not to take lightly

Tempeh is soy fermented by Rhizopus oligosporus and pressed into a compact block. Ciqual gives it 16.1 grams of protein and 6.2 grams of fibre per 100 grams, with only 39 milligrams of sodium: of every ferment on this page, it has the most interesting nutritional profile by a distance.

It is also the only one whose home production carries a genuine microbiological risk. A review published in Heliyon in 2024 on the safety of soybean fermentation notes that spontaneous fermentation, or fermentation run with traditional starters, exposes the product to pathogens, high biogenic amine levels and mycotoxins, and that using a defined, controlled starter culture is what reduces those risks. Tempeh stacks the unfavourable conditions: a protein-rich, low-acid legume substrate, incubation around 30 °C, and 36 to 48 hours of waiting.

If you attempt it, two things are non-negotiable. A commercial Rhizopus oligosporus starter, never a culture scraped off a previous block. And acidification of the soybeans during soaking, with vinegar, which lowers the pH and limits bacterial competition while the mould establishes itself. The dedicated guide to homemade tempeh walks through the procedure.

What to throw out, and what you can keep

A flat whitish film on the surface of a brine is almost always a surface yeast. The NCHFP describes it as wild yeasts and bacteria feeding on the acid, and recommends removing it as often as needed. It lowers the batch’s acidity if left to build up, but it is not a reason to discard.

Fuzzy coloured mould, green, black, pink or blue, is a different matter. It has a mycelium that penetrates the product, and lifting off the visible part does not remove the rest. That batch goes.

The NCHFP asks you to discard pickles that have become soft, slimy or developed a disagreeable odour, with no discussion. A white sediment at the bottom of the jar, on the other hand, is normal: it comes from the fermentation bacteria, or from an anti-caking agent in a salt that was not a pickling salt.

Finally, an NHS reminder that applies to all jars, homemade or not: do not eat food from tins, jars or bottles that are bulging or damaged, and do not eat food that smells bad. And never give honey to a child under twelve months, since it can contain the bacteria that cause infant botulism. The point belongs here because honey keeps appearing in kombucha flavouring suggestions.

Five mistakes that come up constantly

Boiling the jar before a lacto-fermentation. The habit comes from canning, where it makes sense. Here it achieves nothing: the useful flora comes from the vegetable and the container only needs to be clean.

Stopping fermentation after a week. The vegetable is tangy, so people conclude it is done. It has not reached its final acidity and it keeps less well.

Fermenting in a 26 or 28 °C kitchen in summer. Above 24 °C, vegetables go soft. A north-facing cupboard or a cellar beats a sunlit worktop.

Letting pieces sit above the brine. Anything in contact with air moulds. A weight is cheaper than a lost batch.

Using artisanal vinegar of unknown acidity for quick pickles. It is the only step on this page that touches a botulism risk directly, because acidity there replaces fermentation entirely as the barrier.

Adapting to different situations

For a first attempt, start with a soy yoghurt and a jar of carrots or cabbage. Both forgive mistakes, and they let you calibrate your kitchen before investing in a SCOBY or tempeh starter.

In a heated flat in winter, the difficulty is finding somewhere below 24 °C. A hallway, a cellar or a larder beats a kitchen cupboard, even if that means five to six weeks of fermentation instead of three.

For anyone watching their salt, lacto-fermentation is the wrong place to economise, since salt there is a safety parameter. Rinsing sauerkraut briefly in cold water before serving removes some of it, and serving 50 grams as a condiment rather than 200 grams as a vegetable is far more effective than tampering with the recipe.

For anyone sensitive to histamine, taking an MAOI, or prone to food-triggered migraines, long-fermented vegetables and kimchi are the first things to limit. Vinegar pickles, which do not ferment, do not raise this issue.

For anyone pregnant or immunocompromised, the usual caution around unpasteurised products applies. A homemade ferment has had no heat treatment at all, which is the whole point of the method and also its limit in these situations.

The limits of this page

The figures quoted come from composition tables, not from measurements on your jar. Homemade sauerkraut can drift noticeably from Ciqual’s 505 milligrams of sodium depending on how much brine clings to it, and biogenic amines vary by a factor of ten between batches in the published data.

The temperatures and durations come from USDA recommendations relayed by the NCHFP, established for cabbage and cucumbers. They transfer reasonably to carrots, beetroot and radishes, but those are not the vegetables the trials were run on.

No Swiss prices appear here, because the cost of a litre of soy drink, a sachet of starter or a jar varies too much between retailers for an invented range to be worth anything.

Frequently asked questions

Do I need to sterilise jars for lacto-fermentation? No. Wash the container, weight and cover in hot soapy water and rinse with very hot water. The fermentation is seeded by the vegetable’s own flora.

How long before I can taste it? You can taste after a few days, but allow three to four weeks at 21-24 °C for complete fermentation, and five to six weeks at 15-18 °C.

My soy yoghurt will not set. Check the temperature, which should stay near 42 °C, and check the base: almond and rice drinks lack protein and often lack fermentable sugar. Plain unsweetened soy drink is the most reliable choice.

Do homemade ferments cover my B12 needs? No. Tempeh contains 0.019 micrograms per 100 grams against a reference value of 2.5 micrograms a day. A fortified food or a supplement is still necessary.

Is the white film on my brine dangerous? A flat whitish film is a surface yeast: skim it off regularly. Fuzzy coloured mould means the batch goes.

Can I reduce the salt in fermented vegetables? Not in a lacto-fermentation, where salt selects the right bacteria. In vinegar pickles, yes, at a cost in texture and flavour.

How long do vinegar pickles keep? Several weeks in the fridge. They are not shelf-stable preserves, even if the lid has dipped.

Does homemade kombucha contain alcohol? Fermentation turns sugar into acids and also produces some ethanol. The amounts vary far too much between homemade batches for a figure to be given here, which is itself a reason for caution during pregnancy and with children.

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