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The complete guide to sauerkraut

Cabbage, salt and a few weeks. Everything that decides whether a sauerkraut turns out well, step by step, with the figures from official guides.

9 min read First steps Reviewed October 26, 2026 53 facts, each with its source

What sauerkraut is

Sauerkraut is finely cut cabbage fermented with its salt. There's no vinegar and no water: the salt draws the juice out of the cabbage, and that juice becomes the brine1. Inside the jar, with no air, the lactic acid bacteria that come on the cabbage turn its sugars into lactic acid, which holds back harmful bacteria and preserves it2.

Fermentation goes in stages. First, Leuconostoc bacteria take over, releasing gas and pushing the oxygen out of the jar from the start3: those are the bubbles of the first few days. Then other lactic acid bacteria take over and the pH keeps dropping. Over weeks or months it gets down to 3.4, and the flavor turns more sour and sharper4.

What you need

  • A wide-mouth glass jar, 1 liter (1 quart) to start with. Glass and food-grade plastic are good stand-ins for the traditional stoneware crock5. No copper, iron or galvanized metal containers, and no crock with a glaze that could contain lead6: the acid attacks them. A stoneware crock only if it is sold for fermenting (a house rule).
  • A weight that fits through the mouth of the jar: a glass one or a bag of brine.
  • An airlock lid, a regular lid or a cloth. You'll see below how each one works.
  • A kitchen scale, for the cabbage and for the salt.
  • Something to cut with: a sharp knife, a mandoline or a food processor7, and a large bowl for mixing.

The cabbage and the cut

Use firm, fresh heads, and start the sauerkraut 24 to 48 hours after harvest8. Both green and red cabbage work.

Remove the outer leaves, rinse the cabbage under cold water, cut it into quarters and cut out the core9. Then slice it into strips 3 to 5 mm wide10, with a sharp knife, a mandoline or a shredder. Don't chop it like coleslaw: that fine, it bruises and packs too tight, and the salt and juice can't reach all of it11.

Salt it as soon as it's cut. Cutting leaves the sugars open to any microbe, and the salt has to get there quickly so the lactic acid bacteria win12.

Salt: 25 g per kilo

Salt is weighed against the cabbage once it's cut, without outer leaves or core. Fervida uses 2.5%: 25 g per kilo13. BCCDC, British Columbia's public health agency, puts the optimum at 2.25%14 and says to avoid more than 3.5%15, because that much salt holds back the first bacteria of the ferment.

Cut cabbage Salt at 2.5%
500 g (1.1 lb) 12.5 g
1 kg (2.2 lb) 25 g
2 kg (4.4 lb) 50 g
5 kg (11 lb) 125 g

The minimum is 2%, and that is a house rule: reducing the salt in a vegetable ferment is not safe16. Always weigh it17, and use salt without additives, such as canning or pickling salt18. If the recipe has apple, beet or any other extra, the salt is worked out on the weight of everything that goes into the jar.

Try it with your cabbage

Dry-salted

Salt 25g

In rangeAt 2.5%, within the range the guides use.

Massage, press and cover

Mix the salt into the cabbage with clean hands. If it's slow to give up its juice, let it rest for 20 to 30 minutes19 and squeeze again. Pack it into the jar in layers, pressing each layer down until the juice rises. That pushes out the air trapped between the strips20.

A 1-liter jar holds about 950 g (2 lb) of dry-salted vegetables21. Fill it only to the shoulder, leaving about 2 inches (5 cm) free at the top22: during the first 24 to 48 hours, gas pushes the cabbage up23.

If the juice doesn't cover it, add boiled and cooled brine, about 28 g of salt per liter of water24. Put the weight on top. All the cabbage has to stay under the brine from start to finish25.

How to close the jar

The sauerkraut recipes give you three ways to close it. All three work as long as the cabbage stays under the brine.

Closure How it works What you do
Airlock lid Lets gas out without letting air in26 Nothing; just check it stays submerged
Regular lid Has no way out for the gas Loosen it for a moment at each check27
A cloth No lid: plate, weight and a clean towel on top28 Check it 2 or 3 times a week and lift off any film29

Temperature and time

Temperature decides how long it takes. These are the figures of the NCHFP, the USDA-backed National Center for Home Food Preservation3031, except the one above 25 °C (77 °F), which is BCCDC's:

Temperature Time
Below 16 °C (60 °F) May not ferment
16–18 °C (60–65 °F) 5 to 6 weeks
18–21 °C (65–70 °F) 3 to 6 weeks
21–24 °C (70–75 °F) 3 to 4 weeks
24–25 °C (75–77 °F) May turn soft
Above 25 °C (77 °F) May spoil32

Between 18 and 21 °C (65 and 70 °F) the NCHFP gives no times. Fervida uses the span of its two neighboring bands, and that is a house rule. Keep the jar in the dark, because lactic acid bacteria are sensitive to light33.

When it's done

There are three signs, and it's worth checking all three:

  • The bubbling stops. That tells you fermentation has finished34.
  • The pH is below 4.6, the limit the guides set35. Fervida recommends waiting for 4.2 before it goes into the fridge, which is also the figure below which BCCDC lets fresh sauerkraut be packed36, and sits under the 4.4 it asks of unpasteurized vegetables kept cold, against Listeria37.
  • You like the taste. Shorter makes it milder; longer, tangier38.

Red cabbage helps you follow it: as it acidifies it turns from purple to pink. If it goes back to purple, the pH is rising, as happens when mold grows on it outside the brine39.

What can go wrong

What you see What it is What to do
A flat white film Usually kahm yeast40 Skim it off every time it appears41; if it keeps coming back, check the pH: it shouldn't rise above 4.635
Fuzz or green, blue, brown or black spots Mold42 Throw out the whole batch43: it can't be scooped out44
Slimy cabbage It has spoiled45 Throw it out
Soft cabbage Too little salt46 or too much heat Next time, weigh the salt and find a cooler spot
Putrid smell A failed ferment47 Throw it out

A well-fermented sauerkraut smells pleasantly sour, never putrid48. If you can't tell whether a layer is kahm or mold, treat it as mold: when in doubt, throw it out49.

Storing it

Once it's done, close it tightly and move it to the fridge, where it keeps for several months50. Keep the cabbage pressed under its juice. In the cold its flavor keeps changing, but very slowly51.

The recipes, and your own

Every Fervida sauerkraut recipe follows this method, with the same salt and the same times:

  • Homemade sauerkraut: green cabbage and salt. The starting point.
  • Red cabbage sauerkraut: the one that changes color as it sours.
  • With apple and caraway, the classic German kraut, and with juniper and bay leaf, the Alsatian one.
  • Beet and ginger, fennel and lemon and turmeric and black pepper: green cabbage with one extra for color and aroma.
  • Cabbage and carrot with dill, and Salvadoran curtido, with carrot, onion, oregano and a little chili.

To make your own with what you have at home, use "What can I ferment with what I have?". You pick the main vegetable and the extras, and it gives you the weighed salt and the method's times. Extras weigh at most 30% of the main vegetable: a house rule, so that sauerkraut with apple is still sauerkraut. The salt is always worked out on everything that ferments.

There are two things it won't suggest. Garlic is never the main vegetable, because there are no validated recipes for fermenting it52. And nothing is kept in oil, which can create airless pockets where the botulism bacterium grows53.

Where every number comes from

Every number in the text leads to its figure: the exact sentence from the official guide it comes from, in its own language.

  1. 1

    Salt draws the juice out of the cabbage

    “Pack firmly until salt draws juices from cabbage.”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  2. 2

    Without air, bacteria turn sugars into lactic acid, which holds back harmful bacteria and preserves

    “In an anaerobic (oxygen-free) environment, these bacteria convert sugars into lactic acid, which inhibits harmful bacteria and acts as a preservative.”

    University of Illinois Extension · Fermentation handout (2020) · read on October 20, 2026

  3. 3

    Leuconostoc bacteria release gas and push out the oxygen early on

    “Leuconostoc bacteria also release CO2 into the brine establishing an anaerobic environment early in this process.”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.2: Sauerkraut (2024) · read on October 26, 2026

  4. 4

    Over weeks or months, pH drops to 3.4 and the flavor gets sharper

    “Extended fermentations from several weeks to several months will result in lower pH to 3.4; higher acid content from 1.5% to 2.0% (lactic and acetic acid) and provides a sharper flavour.”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.2: Sauerkraut (2024) · read on October 26, 2026

  5. 5

    Glass and food-grade plastic are good stand-ins for a stoneware crock

    “Food-grade plastic and glass containers are excellent substitutes for stone crocks.”

    National Center for Home Food Preservation (USDA, University of Georgia) · Suitable Containers, Covers, and Weights for Fermenting Food · read on October 26, 2026

  6. 6

    No copper, iron or galvanized metal containers, and no lead-glazed crocks

    “Do not use copper, iron, or galvanized metal containers or lead-glazed crocks”

    University of Illinois Extension · Fermentation handout (2020) · read on October 20, 2026

  7. 7

    A sharp knife, a mandoline or a food processor

    “Kraut boards, food processors, sharp knives, and mandolins all work well.”

    University of Illinois Extension · Fermentation handout (2020) · read on October 20, 2026

  8. 8

    Firm, fresh heads, 24 to 48 hours after harvest

    “For the best sauerkraut, use firm heads of fresh cabbage. Shred cabbage and start kraut between 24 and 48 hours after harvest.”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  9. 9

    Outer leaves off, rinsed, quartered and cored

    “Discard outer leaves. Rinse heads under cold running water and drain. Cut heads in quarters and remove cores.”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  10. 10

    Strips 3 to 5 mm wide

    “Generally the cabbage is cored and chopped or sliced to 3 to 5 mm width.”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.2: Sauerkraut (2024) · read on October 26, 2026

  11. 11

    Cut too fine, it bruises and packs too tight, and the salt can't get in

    “If the cabbage is cut like coleslaw, it will bruise and pack too tight. When it packs too tight, it will not allow the salt and liquid to penetrate the cabbage.”

    Washington State University Extension, Lewis County · Sauerkraut Making · read on October 26, 2026

  12. 12

    Salt it right after cutting

    “Following slicing and shredding it is important to add salt quickly to promote LAB growth”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.2: Sauerkraut (2024) · read on October 26, 2026

  13. 13

    25 g of salt per kilo, 2.5%

    “2.5% 25 g / kg food”

    UC Master Food Preservers, Inyo-Mono · Brine Math Made Easy · read on October 20, 2026

  14. 14

    BCCDC puts the optimum at 2.25%

    “Added salt to promote LAB fermentation, optimal 2.25% w/w”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.2: Sauerkraut (2024) · read on October 26, 2026

  15. 15

    Avoid more than 3.5% salt

    “Salt concentrations above 3.5% should be avoided”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.2: Sauerkraut (2024) · read on October 26, 2026

  16. 16

    Reducing salt is not safe

    “It is unsafe to reduce salt in lactofermented vegetables.”

    UC Master Food Preservers, Inyo-Mono · Brine Math Made Easy · read on October 20, 2026

  17. 17

    Weigh the salt

    “It is best to weigh salt for accuracy.”

    University of Illinois Extension · Fermentation handout (2020) · read on October 20, 2026

  18. 18

    Salt without additives, such as canning salt

    “The salt used in fermentation should contain no additives. Canning or pickling salt is recommended”

    University of Illinois Extension · Fermentation handout (2020) · read on October 20, 2026

  19. 19

    Resting 20 to 30 minutes helps the juice come out

    “After mixing in the salt, you may want to leave the mixture for 20-30 minutes to allow for natural juice extraction.”

    University of Illinois Extension · Fermentation handout (2020) · read on October 20, 2026

  20. 20

    Press the cabbage down to squeeze out air bubbles

    “it is important to exclude air by (1) pressing down cabbage and squeezing to remove air bubbles”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.2: Sauerkraut (2024) · read on October 26, 2026

  21. 21

    A 1-liter jar holds about 950 g of dry-salted vegetables

    “Remember, a 1-quart jar will hold 2 pounds of veggies when dry salting”

    K-State Research and Extension (Kansas State University) · Taking a New Look at Fermented Foods (MF3491, June 2020) · read on October 20, 2026

  22. 22

    Fill only to the shoulder, leaving 2 inches (5 cm) free

    “Fill only to the shoulder of the jar, leaving at least 2 inches of head space,”

    K-State Research and Extension (Kansas State University) · Taking a New Look at Fermented Foods (MF3491, June 2020) · read on October 20, 2026

  23. 23

    In the first 24 to 48 hours, gas pushes the cabbage up

    “During initial fermentation (24 to 48 hr), carbon dioxide gas forms and pushes up cabbage, causing heaving.”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.2: Sauerkraut (2024) · read on October 26, 2026

  24. 24

    If the juice doesn't cover it, boiled and cooled brine

    “If juice does not cover cabbage, add boiled and cooled brine (1-1/2 tablespoons of salt per quart of water).”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  25. 25

    Everything under the brine

    “All produce should be submerged in the brine liquid.”

    UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026

  26. 26

    The valve lets the gas out

    “it is important to vent the jar with a one-way valve to release the gases that form during fermentation.”

    K-State Research and Extension (Kansas State University) · Taking a New Look at Fermented Foods (MF3491, June 2020) · read on October 20, 2026

  27. 27

    Without a valve, loosen the lid now and then

    “If a one-way valve is not used, the gases will need to be released manually by loosening the lid occasionally.”

    K-State Research and Extension (Kansas State University) · Taking a New Look at Fermented Foods (MF3491, June 2020) · read on October 20, 2026

  28. 28

    Plate, weight and a clean towel

    “Add plate and weights; cover container with a clean bath towel.”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  29. 29

    With jars as weights, check it 2 to 3 times a week

    “you will have to check the kraut 2 to 3 times each week and remove scum if it forms”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  30. 30

    3 to 4 weeks at 70–75 °F; 5 to 6 at 60–65 °F

    “At temperatures between 70º and 75ºF, kraut will be fully fermented in about 3 to 4 weeks; at 60º to 65ºF, fermentation may take 5 to 6 weeks.”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  31. 31

    Below 60 °F it may not ferment; above 75 °F it softens

    “At temperatures lower than 60ºF, kraut may not ferment. Above 75ºF, kraut may become soft.”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  32. 32

    Above 25 °C (77 °F), fermentation may spoil

    “fermentation at temperatures higher than 25°C may result in spoilage.”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.1: Fermented Vegetables (August 2024, updated December 2024) · read on October 25, 2026

  33. 33

    In the dark: lactic acid bacteria are sensitive to light

    “Containers with fermenting produce should be stored in a dark place, as Lactobacillus are sensitive to light.”

    University of Minnesota Extension · Preserving food at home: Fermentation (reviewed 2026) · read on October 25, 2026

  34. 34

    It's fermented when the bubbling stops

    “until normal fermentation is completed (when bubbling ceases)”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  35. 35

    pH should not go above 4.6

    “The pH can be checked periodically to ensure it does not rise above 4.6.”

    UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026

  36. 36

    Fresh sauerkraut is packed once pH is below 4.2

    “Fresh sauerkraut can be packaged when pH is below 4.2”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.2: Sauerkraut (2024) · read on October 26, 2026

  37. 37

    Unpasteurized vegetables kept cold, below pH 4.4 against Listeria

    “A pH of lower than 4.4 is recommended for unpasteurized pickled vegetables held under refrigeration for L. monocytogenes control.”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.1: Fermented Vegetables (August 2024, updated December 2024) · read on October 25, 2026

  38. 38

    Shorter is milder; longer is tangier

    “Generally, if you want a less sour product, use a shorter fermentation time; longer for more tang.”

    University of Illinois Extension · Fermentation handout (2020) · read on October 20, 2026

  39. 39

    If pH rises, red cabbage turns purple again

    “causing it to change color to purple instead of red due to an increase in pH”

    UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026

  40. 40

    A white film is usually kahm yeast

    “This film is typically yeast, often referred to by home fermenters as Kahm yeast.”

    UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026

  41. 41

    In sauerkraut, kahm is skimmed off now and then

    “For other ferments, such as sauerkraut, yeast should be periodically removed during fermentation.”

    UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026

  42. 42

    Mold is usually green, blue, brown or black

    “Mold is typically green, blue, brown, or black in color.”

    UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026

  43. 43

    If there's mold, the whole batch goes

    “If you confirm mold growth on any part of a ferment, it should be immediately discarded.”

    UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026

  44. 44

    Mold can't be scooped out

    “The mold cannot be scooped out, as the roots will still be in your food and could make you sick.”

    Ask Extension (Clackamas County Extension, Oregon State University) · Pickle/olive brine surface mold spots #889210 · read on October 20, 2026

  45. 45

    Slimy sauerkraut has spoiled: throw it out

    “Slimy kraut (indicates spoilage; discard kraut)”

    Oregon State University Extension Service · Sauerkraut: Problems and solutions · read on October 26, 2026

  46. 46

    Below 1.7% salt it turns soft

    “Insufficient salt (less than 1.7% concentration).”

    Oregon State University Extension Service · Sauerkraut: Problems and solutions · read on October 26, 2026

  47. 47

    A putrid smell means a failed ferment

    “A putrid smell indicates a failed fermentation.”

    UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026

  48. 48

    It smells pleasantly sour, not putrid

    “A fermented fruit or vegetable will smell pleasantly sour but not putrid.”

    UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026

  49. 49

    When in doubt, throw it out

    “When in Doubt—Throw it Out”

    University of Illinois Extension · Fermentation handout (2020) · read on October 20, 2026

  50. 50

    Once fermented, it keeps for months in the fridge, tightly covered

    “Fully fermented kraut may be kept tightly covered in the refrigerator for several months”

    National Center for Home Food Preservation (USDA, University of Georgia) · Sauerkraut · read on October 20, 2026

  51. 51

    In the fridge the flavor keeps changing slowly

    “Expect subtle changes in flavor even during refrigeration (the process slowly continues).”

    University of Illinois Extension · Fermentation handout (2020) · read on October 20, 2026

  52. 52

    There are no validated recipes for fermenting garlic

    “There are currently no validated recipes for fermenting garlic.”

    Ask Extension (Loretta Sweeney, Franklin County, Ohio) · Food preservation and safety: lacto-fermenting garlic #930666 (2026) · read on October 25, 2026

  53. 53

    Oil can create pockets where botulism grows

    “Recipes calling for the addition of oil should be examined with caution as when oil is added it can create micro-environments of oil bubbles that may allow growth of C. botulinum.”

    BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.1: Fermented Vegetables (August 2024, updated December 2024) · read on October 25, 2026

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