The Pickle Hub

Let's get pickling

A friendly corner of the internet for pickling and fermenting at home. Find out how it works, pick something tasty to make, and learn from some brilliant cooks along the way. No lab coat needed.

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What shall we make?

Kimchi 4 recipes · 1 to 2 days, then the fridge Quick vinegar pickles 4 recipes · ready in hours Sauerkraut 4 recipes · 1 to 6 weeks Brine ferments 5 recipes · days to weeks Fermented drinks 7 recipes · cheong, kombucha and soda

Pickling vs. fermenting

Both are old ways of keeping food, and both leave you with something sour and tangy in a jar, which is why people call the results of both "pickles". The difference is where the sourness comes from.

When you pickle, you add the acid yourself: vegetables go into vinegar and are ready within hours. When you ferment, you add salt and let bacteria that already live on the vegetables make the acid for you, turning the food's natural sugars into lactic acid over days or weeks. So not every pickle is fermented, and not every fermented food is a pickle.

PicklingFermenting
Where the acid comes fromVinegar you addLactic acid made by bacteria on the food
What it sits inVinegar, usually with water, salt and sugarA salt and water brine, or the veg's own juices drawn out by salt
How longHoursDays to weeks, depending on salt, temperature and the food
FlavourBright and sharp, tasting of the veg and spicesA deeper, more complex sourness that builds over time
Live culturesNoYes, which may benefit your gut
Good first triesOnions, beetroot, carrots, cucumber, red cabbageCabbage, carrots, beetroot, celery, cucumber, chilli

What they have in common: both methods make the food acidic enough (below pH 4.6) that harmful bacteria, including the one that causes botulism, can't grow. The science section explains why that number matters.

A note on storage: vinegar pickles can only live in the cupboard if the jars have been properly heat-processed and sealed. Quick "fridge pickles" stay in the fridge. Fermented veg also belongs in the fridge once it tastes right, because the cold slows fermentation and keeps it crunchy.

Sources: Kilner, "What is the difference between fermenting and pickling?"; Wendy the Food Scientist, "Fermentation vs. Pickling".

The Science

Food goes off for two main reasons: microbes (bacteria, yeasts and moulds) grow on it, and the food's own enzymes keep working after it's harvested. Preserving food means changing the conditions so the wrong microbes can't thrive.

There are only a handful of ways to do that: heat, drying, cold, lowering the pH (making it more acidic), cutting off oxygen and taking away the nutrients microbes feed on. Pickling and fermenting lean mostly on acid. Fermenting adds salt and keeps the food under brine, away from the air.

Inside a ferment, and where it sits on the pH scale A jar of fermenting vegetables held under brine by a weight, with lactic acid bacteria and carbon dioxide bubbles in the brine and a crossed-out mould spore in the air gap. Beside it, a pH scale from 2 to 8 marks vinegar near 2.5, a finished ferment near 3.5, fresh veg near 6 and water at 7. A dashed line at pH 4.6 marks the point below which botulism bacteria cannot grow; fermenting moves the veg from about pH 6 down past that line. No air, no mould Lactic acid bacteria CO₂ bubbles 2 3 4 5 6 7 8 4.6 pH Vinegar Finished ferment Fresh veg Water (neutral) Too acidic for botulism fermenting
As lactic acid bacteria turn the veg's sugars into lactic acid, the pH drops from around 6 to past the 4.6 safety line. The weight keeps everything under the brine, away from the air that moulds need.

Acid and the pH 4.6 line

pH measures acidity: the lower the number, the more acidic. Below pH 4.6, the bacteria that cause botulism can't grow, and that's the target for both methods. Vinegar gets a pickle there straight away. A ferment gets there gradually, as lactic acid bacteria eat the sugars in the veg and turn them into lactic acid. That acid is also what gives ferments their tang.

Two kinds of fermentation

In lactic acid fermentation, bacteria turn sugars into lactic acid. It's how sauerkraut, kimchi, fermented pickles, yoghurt and some cured meats are made. In alcoholic fermentation, yeasts turn sugars into alcohol and carbon dioxide, which is how beer and wine are made. Fruit left to its own devices tends to go the alcoholic route, because yeasts cope with fruit's acidity better than most bacteria do.

Why acid isn't the whole story: yeasts and moulds

Yeasts and moulds are fungi, and unlike most bacteria they're comfortable in acid. Yeasts grow best between about pH 3.5 and 4.5, which is exactly where a finished ferment sits. Moulds tolerate anything from about pH 3.5 to 8. So a jar that's acidic enough to be safe from botulism can still grow a film or mould on top.

Moulds spread through spores that drift through the air and settle on food, and they need oxygen to grow. That's why fermenting recipes are so insistent about keeping everything below the brine with a weight: no air, no mould.

Why veg must stay under the brine, and where yeasts and moulds grow Two jars with mould spores drifting in the air above them. In the left jar, veg floats above the brine and has grown fuzzy mould. In the right jar, a weight holds the veg under the brine and it stays clean. Below, a pH chart shows yeasts growing between pH 3.5 and 4.5 and moulds between pH 3.5 and 8, both on the acidic side of the pH 4.6 botulism line. mould spores in the air Veg above the brine mould takes hold Weighted under the brine nothing for mould to grab Too acidic for botulism Yeasts Moulds 234 5678 4.6 pH
Mould spores are always in the air and need oxygen to grow, so any veg poking above the brine is a landing pad. Acid doesn't stop them either: yeasts grow between about pH 3.5 and 4.5, right where a finished ferment sits.

Both also need water. Microbes can only use "free" water, which scientists measure as water activity, on a scale from 0 (bone dry) to 1 (pure water). Yeasts stop growing below about 0.9 and moulds below about 0.8. Very salty or sugary foods, like salt cod or jam, preserve themselves partly this way. Fermenting brines are far weaker than that, so in a ferment the salt's job is to favour the good bacteria, not to stop yeasts and moulds on its own.

Cold

Keeping food below 4°C slows microbes down and slows the chemical reactions that spoil food. It can't undo spoilage that has already started, only delay it. For ferments, moving the jar to the fridge is how you hit the pause button once it tastes the way you like.

The fridge pauses a ferment A thermometer marks room temperature, 4°C and 0°C. A jar on the counter at room temperature is full of bacteria and bubbles. An arrow labelled "once it tastes right" leads to the same jar inside a fridge below 4°C, now with only a few bubbles: the ferment is paused and stays crunchy. Room temp 4°C 0°C freezing On the counter bacteria busy once it tastes right In the fridge paused, stays crunchy
At room temperature the bacteria are busy. Below 4°C they slow right down, so the fridge holds your ferment at the flavour you like and helps it keep its crunch.

Why eat fermented food?

Fermenting doesn't just preserve food. Live ferments carry the bacteria that made them, and there's growing evidence that eating them regularly is good for your gut.

Sources: Britannica, "Food preservation: Fungi" and "Control of microbial contamination"; Kilner; Wendy the Food Scientist; Wastyk et al., "Gut-microbiota-targeted diets modulate human immune status", Cell (2021).

Getting started

You don't need special kit or experience: a clean jar, the right salt, some vegetables and a bit of patience will do. A great first project is a single, simple one, like sauerkraut.

Two ways to ferment veg

Dry salting is for vegetables that give up their own juice, such as cabbage, carrots, beetroot, radishes and onions. You sprinkle salt over them, massage it in and pack them down until they're sitting in their own brine. Brining is for whole or chunky vegetables that won't make enough liquid, such as cucumbers, green beans, cauliflower, peppers and garlic. You pour salty water over them instead.

What you need

  • A jar. Wide-mouthed is easiest to pack. Old jam or pasta sauce jars work fine.
  • A weight to keep everything under the brine. A fermentation weight is ideal, but a small zip-lock bag filled with brine or a shot glass does the job.
  • A lid. A fermentation lid lets gas out by itself. With a normal lid, rest it loosely or open the jar once a day to let the gas out.
  • A plate or tray underneath, because lively ferments can bubble over.
  • Kitchen scales. Salt is the one thing worth weighing precisely.

Salt

Use sea salt, pickling salt or kosher salt. Avoid iodised salt and salt with anti-caking agents, which can hold back the bacteria you want. Always weigh it rather than using spoons: a tablespoon of fine sea salt weighs almost twice as much as a tablespoon of coarse kosher salt.

StrengthUse it for
2% of the veg's weightDry-salted ferments like sauerkraut and kimchi (20 g salt per 1 kg of veg)
3% of the waterA lighter brine for quick or delicate ferments
3.5% of the waterThe all-purpose brine (35 g salt per litre of water)
5% of the waterHot weather, long ferments or extra crunch

The brine strengths above are a percentage of the water alone, so in the brine calculator enter just the water's weight. For a dry-salted ferment, enter the weight of the veg.

Where to keep it

Find a spot out of direct sunlight, away from the oven, radiators and outside walls, where the temperature stays steady and you'll remember to check it every day. Temperature sets the pace:

TemperatureWhat happensTypical time
15 to 18°CSlow, with a complex flavourWeeks to months
18 to 24°CThe sweet spot1 to 4 weeks
24 to 29°CFast, with a sharper flavour2 to 5 days
Above 29°CRisky: add more salt or find somewhere coolerNot recommended

Keeping things clean

Wash everything (jars, weights, lids, your hands and the worktop) in hot, soapy water, rinse well and leave it to air dry. A dishwasher is fine for cleaning. For vegetable ferments that's enough: the lactic acid the bacteria make protects the jar, so you don't need to sanitise. Do sanitise if your home has damp or mould problems, or if your last batch grew mould or a yeast film. Two things to avoid: don't plunge glass jars into boiling water, because they can crack, and don't clean with vinegar and bicarbonate of soda together, because they cancel each other out.

Is it working?

Start tasting after about five days. Bubbles mean the bacteria are busy, and as the bubbling slows the main fermentation is winding down. A healthy ferment smells pleasantly sour, and cloudy brine and a fizz when you open the jar are both normal. When it tastes right to you, move it to the fridge. Most fermented veg keeps for months there.

Throw it out if you see fuzzy mould, if the veg turns slimy or if it smells rotten rather than sour. The safety section covers what's harmless and what isn't.

Ferment what's in season, and what's left over

Produce fermented at its peak gives the freshest, best-flavoured results, and fermenting is a good way to stop food going to waste. Slightly tired or bruised vegetables are fine once you've trimmed the bad bits. Even scraps can be useful: pineapple peel makes tepache (a fizzy drink), ginger peel can start a ginger bug and watermelon rind can be pickled in brine.

In season in the UK

    British produce worth fermenting or pickling. Seasons shift with the weather and where you live, so check what your greengrocer or farm shop has.

    Sources: The Ferment Guide, "How to ferment at home"; Edinburgh Food & Drink Academy; Révolution Fermentation on cleaning equipment, reducing waste and seasonal fermenting. Seasonal calendar: Hubbub, with cabbage and cucumbers from Oddbox.

    Brine calculator

    Work out how much salt to add, based on the total weight of everything in the jar.

    Brine strength
    Total weight

    Everything going in the jar: veg, aromatics and water. If your recipe gives the brine as a percentage of the water only, enter just the water's weight.

    Salt needed 0 g Enter a weight to see how much salt you need.
    How to weigh it: put the empty jar on the scale and zero it. Pack in the veg and aromatics, top up with water until everything is covered, then read the weight.

    Technique

    Quick vinegar pickles

    A quick pickle is just vegetables in vinegar: no fermenting, no special kit, and ready in anything from a few minutes to a couple of days.

    Here are four ways to do it, from a London chef's crinkle-cut cucumbers to a two-ingredient shortcut. Pick a video to watch it and see the method underneath.

    Good to know: quick pickles aren't heat-processed, so keep them in the fridge.

    Technique

    Sauerkraut

    Sauerkraut is just cabbage and salt. The salt draws the water out of the cabbage to make its own brine, and the bacteria already living on the leaves do the rest, turning it tangy over a few weeks.

    Good to know: keep the cabbage pressed under its brine the whole time, because anything poking above it can go mouldy. Weigh your salt (the brine calculator will work it out), taste from about day 5, and move the jar to the fridge once it's as sour as you like.

    Technique

    Brine ferments

    Brine ferments are for whole or chunky veg, and even fruit, that won't make enough juice of their own: you cover them in salty water and let the bacteria get to work.

    Most of the recipes below weigh the veg and water together and add salt as a percentage of the total, which is exactly what the brine calculator does.

    Good to know: keep everything under the brine, using a weight if anything floats, and don't go below 2% salt. Taste from day 2 to 5, then move the jar to the fridge once it's as sour as you like.

    Technique

    Kimchi

    Kimchi is Korea's great fermented side dish: salted napa cabbage coated in a paste of chilli, garlic, ginger and fish sauce, then left to ferment until it's sour, spicy and a little fizzy.

    Unlike sauerkraut, the cabbage is usually salted first and then rinsed, so there's no salt percentage to weigh. The courgette version below is the exception: it's salted at 2% like a kraut.

    Good to know: wear gloves when you mix in the chilli paste, press the kimchi down so it sits under its own juice, and leave room in the jar because it fizzes. A day or two at room temperature, then the fridge, where it keeps getting more sour.

    Technique

    Fermented drinks

    From sweet fruit syrups to fun, fizzy sodas. Pick a type below: cheong (Korean fruit syrups made with sugar), kombucha (fermented sweet tea) or soda (ginger bug sodas, tepache and fruit kvass).

    Good to know: fizzy drinks build up pressure. Use bottles made for fermenting, leave space at the top, open them once a day to let the gas out, and chill them once they're fizzy enough.

    Safety & troubleshooting

    Home fermenting is very safe when you stick to three things: enough salt, everything under the brine, and a clean jar. Most of what looks alarming is perfectly normal. A few things mean the batch should go in the bin.

    The golden rules

    • Weigh your salt and never go below the recipe. For vegetable ferments, 2% is the minimum. You can go higher, never lower.
    • Keep everything under the brine, ideally 2.5 to 5 cm under, with a weight. Anything exposed to the air can go mouldy.
    • Clean, don't sterilise. Wash jars, weights and lids in hot, soapy water and rinse well. Lactic acid protects the ferment from there.
    • Ferment somewhere steady and out of the sun. 21 to 24°C is ideal for sauerkraut. Below about 15°C it may not ferment, and above 24°C it can turn soft.
    • Use the right salt: sea, pickling or kosher salt. Iodised salt and anti-caking agents can stop the fermentation working and discolour it.
    • Use glass, ceramic or food-grade plastic. Never bin bags. Keep brass, copper and zinc utensils well away.
    • If in doubt, throw it out. It's only cabbage and salt, and the next batch will be better.

    Perfectly normal

    • Bubbles, fizz and a hiss when you open the jar: that's carbon dioxide from the bacteria at work.
    • Cloudy brine, and a fine white sediment at the bottom of the jar.
    • Brine rising up the jar or overflowing in the first week. Stand it on a plate and leave some space at the top.
    • A sour, tangy smell. Cabbage ferments can smell a bit funky too, especially early on.
    • Tasting a little odd in the first few days, before the sourness has built up.

    Harmless, but worth fixing

    Kahm yeast is a flat, white, sometimes wrinkly film on the surface of the brine. It isn't harmful, but it can make the ferment taste off. Skim it off, press everything back under the brine and carry on. It's more common in warm kitchens and low-salt ferments.

    Throw it out

    • Fuzzy, raised mould in green, black, pink or white, especially if it has spread or is growing below the brine.
    • Slimy vegetables, or pickles that are soft and slippery.
    • A rotten smell rather than a sour one.
    • Anything that has been in contact with brass, copper or zinc utensils.
    About small spots of mould: some experienced fermenters scoop out a small spot that's only on the surface, along with a good margin of veg around it. The safest choice is still to throw the batch away, and that's what we'd recommend while you're learning.

    Troubleshooting

    ProblemLikely causeWhat to do
    Soft or mushyToo little salt, too warm, fermented too long, or the cucumber's blossom end left onUse more salt or a stronger brine, ferment somewhere cooler and trim the blossom ends. Throw it out if it's slimy
    Too saltyA young ferment, or too much saltGive it more time, since the bacteria use up some salt, or rinse it before eating
    Not sour enoughToo cool, or not enough timeWait longer or move it somewhere warmer
    No bubblesToo cold, or still early daysFind a warmer spot, between 18 and 24°C, and give it a few days
    OverflowingCarbon dioxide from a lively fermentLeave space at the top, stand the jar on a plate and let the gas out if the lid is sealed
    White filmKahm yeastSkim it off and keep everything under the brine
    ShrivelledBrine too strong, or veg that wasn't freshFollow the recipe's salt and use veg within a day of picking or buying
    Hollow cucumbersCucumbers too big, or left too long before briningUse small, firm, fresh cucumbers
    Dark or discolouredIodised salt, ground spices, hard water or reactive metalUse pickling salt and whole spices. Throw it out if brass, copper or zinc was involved

    What about botulism?

    The bacteria that cause botulism thrive without oxygen, just like the good fermenting bacteria, but they can't cope with salt and acid. A properly salted ferment quickly becomes too acidic for them: they can't grow below pH 4.6, and a finished ferment sits well below that (see The Science). That's why the salt rules above matter. Botulism from properly salted vegetable ferments is very rare, but if you want extra reassurance you can check a batch with pH strips or a pH meter.

    Storing your ferments

    Once a ferment tastes right, move it to the fridge with the lid on tight, where it keeps for several months. Quick vinegar pickles belong in the fridge from the start. Only jars that have been heat-processed and sealed using a tested method are safe to keep in the cupboard.

    Sources: National Center for Home Food Preservation on problems with fermented pickles, containers, covers and weights and sauerkraut; The Ferment Guide; Edinburgh Food & Drink Academy; Révolution Fermentation; Ethan Chlebowski.

    Shop

    You don't need much kit to get going: a few good jars, something to keep the veg under the brine, and scales so your salt is spot on. Here are some good places to start.

    About these links: they're Amazon affiliate links. If you buy something through one, The Pickle Hub gets a small commission and you pay the same price. As an Amazon Associate I earn from qualifying purchases.

    • Jars

      Kilner jars

      The classic for ferments and fridge pickles. Clip-top jars can let a little gas escape as a ferment bubbles, and screw-top ones are easy to open for a daily taste. Get a few sizes: a 1 litre jar holds a small cabbage's worth of sauerkraut.

      Browse Kilner jars on Amazon ↗ Affiliate link
    • Fermenting kit

      Kilner fermenting accessories

      Airlock lids, glass weights, funnels and more. If you only add one thing, make it a weight: anything poking up above the brine is where mould gets started (see Safety & troubleshooting).

      Browse Kilner accessories on Amazon ↗ Affiliate link
    • Scales

      Salter Arc digital kitchen scale

      Salt is the one thing worth getting exactly right, and spoonfuls vary a lot. This one weighs in grams, takes up to 3 kg, and can reset to zero with the jar already on it, which makes the brine calculator a breeze.

      See the scale on Amazon ↗ Affiliate link

    Prices and stock are set by Amazon and can change.

    Sources & resources

    Want to go further? Here are some of the best free guides and recipes we've found. None of them need a subscription.

    Food safety guides

    • Fermenting and Pickling. National Center for Home Food Preservation (University of Georgia). Tested, research-backed methods and the place to check when you're unsure.
    • Fermented dill pickles and Sauerkraut. National Center for Home Food Preservation. Step-by-step tested recipes.
    • USDA Complete Guide to Home Canning. Free to download, if you ever want to store pickles in the cupboard rather than the fridge.
    • Making sauerkraut. Clemson University Home & Garden Information Center. A clear fact sheet with troubleshooting.

    Recipes to try

    The science

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