Fermenting Vegetables: A Traditional Country Skill

Why Fermentation Still Earns Its Place

Before freezers and imported vegetables, a British kitchen garden had to feed a household through winter, and fermentation was one of the quiet ways it managed. Cabbages, kale, carrots, mooli, beetroot and runner beans all arrive in gluts, and salting them in a crock turns a two-week surplus into six months of eating. There is no electricity involved, no sterilising at pressure, no special equipment beyond a jar, a weight and a cool corner of the house.

The principle is simple enough. Lactic acid bacteria already live on the surface of leaves and roots. Given salt, an anaerobic environment and a sensible temperature, they multiply and produce lactic acid, which drops the pH and preserves the vegetables while making them taste sharper and more digestible. Your job is to give them the right conditions and then leave them alone.

Salt Ratios Worth Committing to Memory

Salt is the whole game. Too little and unwanted bacteria and moulds get a foothold; too much and the lactic bacteria stall, leaving you with salty vegetables and no sourness. The reliable method is to weigh everything and work in percentages.

• Dry-salted shreds (sauerkraut): 2% salt by weight of prepared vegetables — 20g of salt for every 1kg of shredded cabbage. Add 2.5% for a firmer, longer-keeping batch in a warm kitchen.
• Brined whole or chunked vegetables: a 5% brine, which is 50g of salt dissolved in 1 litre of water. Use this for carrots, beetroot, beans and cucumbers.
• Kimchi-style mixes: salt the prepared leaves at 2–3% for two to four hours, rinse lightly, then dress with a paste. A 5% brine can be used instead if you prefer to soak.

Weigh the salt. A tablespoon of fine sea salt and a tablespoon of coarse flakes are very different amounts. Use non-iodised salt with no anti-caking agents — iodised salt can inhibit fermentation and additives can cloud the brine. British sea salt or a plain coarse salt is ideal.

Jars, Crocks and Cleanliness

You do not need a cellar full of stoneware, though if you have inherited one, use it. A large glass jar with a wide neck is easier to manage than a narrow one. Wash it in hot soapy water, rinse well, then either run it through a hot oven for ten minutes or rinse with a sterilising solution and let it drain. Wipe the rim with a little vinegar before you seal it.

The second piece of kit matters just as much: something to hold the vegetables below the brine. A clean glass weight, a smaller filled jar, a well-scrubbed stone or a bag of 2% brine all work. Anything above the surface will spoil — that is where moulds live. Fit a lid loosely, or use an airlock, so carbon dioxide can escape without letting air in.

A Plain Sauerkraut, Step by Step

Take a firm white or savoy cabbage, remove the outer leaves and set two aside. Quarter, core and shred finely — about 3mm. Weigh the shreds and add 2% salt. Now massage the salt in with clean hands for five to ten minutes, until the cabbage goes limp and a pool of brine forms in the bowl.

Pack it into the jar a handful at a time, pressing down firmly with your fist or a pestle so no air pockets remain and the brine rises above the vegetables. Lay the reserved leaves over the top, add the weight, and make sure the liquid sits at least a centimetre above everything. If the cabbage is dry, top up with a little 2% brine rather than plain water.

Leave it at 18–20°C, out of direct sunlight. It will begin to bubble within two or three days. Start tasting after five days; a young kraut is crisp and mild, and it grows sharper with each week. Most people jar it up and move it to the fridge at three to four weeks, which slows fermentation but does not stop it. It keeps for months.

Kimchi-Style Mixes from British Crops

The same method adapts beautifully to what grows here. Use pointed cabbage, kale, or a mix of carrot, mooli and turnip. Salt the prepared vegetables at 2–3% for a few hours, turning them now and then, then rinse briefly and drain.

For the paste, blend garlic, ginger, a little chilli and a spoonful of rice flour cooked to a thin porridge — this feeds the bacteria and helps the paste cling. Add a splash of fish sauce if you like, or a spoonful of miso for a vegetarian version. Work the paste through the drained vegetables with clean hands, pack down firmly, weight and seal. Kimchi-style mixes ferment faster than kraut in a warm kitchen; taste after three days.

Staying Safe and Knowing What to Look For

Trust your senses, but understand what you are seeing. A white, powdery film on the surface is usually kahm yeast — harmless, if a little musty. Skim it off, top up with brine and carry on. Fuzzy mould in green, blue or black, or any pink or slimy growth, means the batch goes on the compost. Never scrape mould off and eat what lies beneath.

Keep vegetables submerged, keep everything clean, and keep the temperature steady. A finished ferment should smell sour and clean, taste salty and sharp, and reach a pH below 4.6 — a reading you can check with a strip if you are unsure. Discard anything soft, slimy, or smells of rot, and start again with fresh produce.

Begin with one jar of cabbage. Once you have watched it turn from raw and crunchy to bright and sour on your own kitchen table, the winter glut stops being a problem and becomes something you look forward to.