Sauerkraut From Scratch: Cabbage, Salt and Time

Sauerkraut is cabbage and salt. There is no starter culture, no whey, no sachet of anything. You cut a cabbage into ribbons, add two per cent of its weight in salt, squeeze it until it weeps, push it under its own liquid and go away for three weeks. The bacteria are already on the leaves. Your entire job is to build a room that suits them and locks everyone else out.

I make it in October, when the big white heads are cheap and dense, and it lives in the fridge until spring. Shop sauerkraut in a jar has been pasteurised, which kills the organisms that made it and leaves you with sour wet cabbage — perfectly usable in a stew, and a completely different substance from the live stuff, which is crunchy, fizzy on the tongue and smells of apples and pepper.

Salt, cabbage, and a persistent legend

The story you will hear is that sauerkraut came from China, fed to the labourers on the Great Wall, fermented in rice wine, and carried west into Europe by the Tatars under Genghis Khan. It appears in a great many cookbooks. There is no evidence for it. Chinese suan cai is genuinely ancient and genuinely fermented cabbage, and Roman writers including Cato describe preserving cabbage in salt, and those two facts almost certainly have nothing to do with each other — brine, cabbage and cold winters occurred to a lot of people independently, because there are only so many things you can do with a glut of brassica and no refrigeration.

What is documented is that James Cook took sauerkraut to sea. On the Resolution voyage of 1772-75 he carried it in barrels and imposed it on a reluctant crew, and in 1776 the Royal Society gave him the Copley Medal, its highest honour, largely for the paper he wrote on keeping sailors free of scurvy. Sauerkraut is a modest source of vitamin C — fresh cabbage has more — but it was a source that survived two years in a hold, which is the entire point.

In Germany the cabbage itself has terroir. The Filderkraut, a pointed white cabbage grown on the Filder plateau south of Stuttgart, has been the prestige sauerkraut cabbage for two centuries, tender enough that it ferments finer and sweeter than a supermarket drumhead. Leinfelden-Echterdingen still holds a Filderkrautfest every autumn. And the word travelled badly: British and American soldiers called German troops “Krauts” from the First World War onwards, and in 1918 American restaurants briefly renamed the stuff liberty cabbage, an act of culinary patriotism that fooled precisely nobody and lasted about a year.

What is actually happening in the jar

The salt is doing two jobs simultaneously. Osmotically, it pulls water out of the cabbage cells — that pool in the bowl is the cabbage’s own sap, drawn out through cell walls you have already broken by massaging. That liquid becomes the brine, and the brine excludes oxygen, which is what makes the whole thing safe. Selectively, 2% salt is comfortable for lactic acid bacteria and hostile to most of the moulds and spoilage organisms that would otherwise turn a cabbage to slime.

Then there is a succession, and it happens in a fixed order every time. Leuconostoc mesenteroides goes first: it tolerates the salt, works happily at lower temperatures, and produces carbon dioxide along with both lactic and acetic acid. That is the fizzing you see in week one, and the CO2 blanket it lays over the surface is doing you a favour by pushing out the last of the air. As the acid builds, Leuconostoc poisons its own environment and dies back at around pH 4. Lactobacillus plantarum takes over, is far more acid-tolerant, and grinds the pH down to about 3.4, which is where it stops. Below that, essentially nothing pathogenic can grow. There is no recorded case of botulism from properly submerged sauerkraut.

The 2% figure matters more than people expect. Under about 1.5%, the fermentation runs fast and loose, other organisms get a foothold, and the texture goes soft. Over 3%, the lactobacilli themselves start to struggle, the fermentation stalls half-finished, and you get salty cabbage that never turns properly sour. Weigh the shredded cabbage — not the whole head, whose core and outer leaves you have removed — and take 2% of that. It is the one number in this recipe.

Temperature is the flavour dial. At 22-24°C it will be done in ten days and taste blunt and slightly harsh. At 15-18°C it takes four or five weeks and tastes rounder, more complex, more like something. Above about 26°C, cabbage pectinases and the wrong bacteria combine to give you mush. A north-facing cupboard in autumn is close to ideal, which is not a coincidence.

The toasted caraway is my one liberty. Raw caraway is medicinal and it stays medicinal for three weeks in brine. Ninety seconds in a dry pan converts some of the carvone into softer, nuttier aromatics, and the seeds arrive in the finished kraut tasting like rye bread instead of a cough sweet.

The shred, and the kit you need

Thickness decides texture, and 2-3 mm is the number. Finer than that and the ribbons go limp within a week and end up as a wet tangle. Much coarser and the salt takes days to penetrate, which gives the surface bacteria a head start on the interior. A cheap mandoline with a guard does this in four minutes; a long knife and a quartered cabbage laid flat-side down does it in ten. Cut across the grain, not with it, so each ribbon is a short section of leaf rather than a long tough rib.

Take the core out. It is dense, it ferments at a different rate, and it stays woody. The outer leaves you peel off at the start are worth keeping whole — folded over the surface, they act as a raft that stops small shreds bobbing up into the air, and they are far more effective than a disc of baking paper.

You do not need a crock. A 2-litre Kilner jar works, and the only real question is how you handle the gas. Fermentation produces a serious volume of CO2 in the first week, and a sealed jar will either vent past the seal or crack. An airlock lid solves it for a few pounds. Failing that, close the jar loosely and burp it once a day over the sink — the tray underneath is because it will overflow, usually on day three, usually overnight.

The traditional German Gärtopf — a stoneware crock with a water-filled channel around the rim that the lid sits in — is a one-way valve invented long before anyone knew what a lactobacillus was. Gas escapes through the moat, air never comes back. If you intend to make kraut every autumn for the next thirty years, buy one. If this is your first jar, do not.

For a weight, a scrubbed river stone works, so does a smaller jar filled with water, so does a freezer bag of 2% brine — the bag is best because it moulds to the shape of the vessel and seals the edges. Use brine rather than plain water in the bag, so a leak dilutes nothing.

Every way it goes wrong

White film on the surface. Almost always kahm yeast: flat, wrinkled, chalk-white, smells yeasty. Harmless. Skim it, make sure everything is still submerged, carry on. It appears when the surface sees air, so it is a sign your weight has slipped.

Fuzzy, coloured mould — blue, green, black, pink and raised. Different problem. If it is a small patch on the surface and everything below is firmly under brine, lift it out generously along with the leaf beneath it. If it has fingers reaching down into the cabbage, or the whole jar smells of wet cellar, throw it away. That is not a common outcome and it is nearly always a submersion failure.

Slimy, ropey brine that strings off the spoon. This is Leuconostoc making dextran, usually because the jar got warm early or the salt is uneven. If it happens in week one, wait — the plantarum phase generally eats through it and the texture recovers. If the kraut is still ropey at three weeks, it is compost.

Pink cabbage. Certain yeasts, encouraged by too much salt or salt that was never properly distributed. Discard it and massage harder next time.

No brine after 12 hours. Either the cabbage was old and dry or you did not squeeze it hard enough. Top up with 2% brine and stop worrying; it changes nothing except the mild dilution.

Soft kraut, no crunch. Too warm, or too little salt, or both. Iodised table salt and anything with anti-caking agents can also do it, so use pure sea salt or kosher salt.

Eating it

Live sauerkraut, straight from the jar, is a condiment: sharp, cold, crunchy, and superb next to anything fatty. It is what a roast pork knuckle wants — Schweinshaxe with cold kraut is a better plate than Schweinshaxe with hot kraut, though Bavaria will argue.

Cooked, it becomes a different ingredient entirely. Twenty minutes in goose fat with an onion and a splash of Riesling turns it mellow and savoury, which is the foundation of Alsace’s choucroute garnie and of Czech vepřo knedlo zelo. Estonian mulgikapsad simmers it with pork and barley until it barely resembles cabbage, and Slovak kapustnica uses the brine itself as the souring agent in the broth. Save that brine — it is the best part, and it makes a startling addition to a salad dressing.

Half a head of cabbage in a 1-litre jar works exactly the same way and is the sensible first attempt — 1 kg of shredded cabbage, 20 g of salt, same three weeks. The reason people make 2 kg at a time is that the massaging is the only real labour, and it takes no longer for a big batch than a small one.

Rinsing is a matter of taste and mostly a matter of your salt discipline. At 2%, correctly fermented, it does not need it, and rinsing washes away the acid you spent three weeks growing. If you want it milder, squeeze rather than rinse. And keep a jar of red cabbage going alongside if you like: fermented, it is fierce and magenta, and it sits somewhere between this and a braised Rotkohl with apple and clove.