Fermented Red Cabbage: Salt Ratio and Time
Published
Fermented red cabbage uses salt at 2.25% of the shredded cabbage weight by default: 51 g (1.8 oz) for 5 lb (2.27 kg). The calculator's time is 21 to 28 days at 70 to 75°F (21 to 24°C).
No source opened gives a recipe for red cabbage by name. Every figure here describes cabbage in general, and the times are the National Center for Home Food Preservation sauerkraut times. For green cabbage, see the sauerkraut salt ratio guide.
Quick answer
For red cabbage, use salt equal to 2.25% of the vegetables' weight: 51 g (1.8 oz) for 5 lb (2.27 kg). Ferment for 21 to 42 days, depending on the room temperature.
- Diamond Crystal kosher, for 5 lb (2.27 kg)
- 3/8 cup
- Morton kosher, for 5 lb (2.27 kg)
- 3 1/2 Tbsp
- Table salt, for 5 lb (2.27 kg)
- 3 Tbsp
- Ferment window
- 21 to 42 days
- depends on room temperature, see the table in the guide
Warnings
NCHFP says to keep kraut at 70 to 75°F (21 to 24°C). Below 60°F (16°C) it may not ferment, and above 75°F (24°C) it may become soft. America's Test Kitchen ferments kraut at 50 to 70°F (10 to 21°C) and says that above 75°F (24°C) food safety becomes a concern.
Discard the ferment if it is slimy or smells spoiled or rotten (Illinois Extension). NCHFP's Dill Pickles page (https://nchfp.uga.edu/how/ferment/recipes/dill-pickles/) says to discard fermented pickles that become soft, slimy or develop a disagreeable odor.
Press the salted vegetables down and weigh them so they stay under the juice they release for the whole ferment. Vegetables that stick out of the liquid are exposed to air, which lets mold and yeast grow.
Do not reduce the salt below the amount shown. The National Center for Home Food Preservation says salt is vital to the safety and texture of fermented vegetables and not to cut back on the salt required, and the Inyo-Mono Master Food Preserver Program (UC Cooperative Extension) says it is unsafe to reduce salt in lactofermented vegetables.
Fermenting is not canning. This calculator gives no canning instructions. Do not can the fermented result unless you follow a tested canning procedure from the National Center for Home Food Preservation or a university extension service.
Notes
The Humboldt and Del Norte Master Food Preservers (UC Cooperative Extension) say salt under 1.5% lets the cabbage rot, under 2% can give soft or slimy kraut, and over 3.5% may inhibit the lactic acid bacteria. The University of Wisconsin-Extension says too much salt slows fermentation and can cause an acrid flavor, darker color or pink yeasts. NC State Extension (https://content.ces.ncsu.edu/pickle-and-pickle-product-problems) lists salt over 2.25% as one cause of pink sauerkraut, along with unevenly distributed salt and kraut that was not covered or weighted during fermentation, and it calls pink sauerkraut unsafe. The 2.25% strength is at that figure and the 2.5% strength is above it, although Virginia Cooperative Extension and the University of Wisconsin-Extension accept 2.5%.
If the juice does not cover the cabbage, NCHFP says to add a brine of 1 1/2 tablespoons of salt per quart of water, boiled and cooled. University of Alaska Fairbanks Extension says the cabbage should be covered with 1 to 2 inches of its own juice.
University of Minnesota Extension says a ferment is ready when the pH is 4.60 or lower and bubbling has stopped. UC Davis says the pH must be below 4.6 to prevent botulism and that its overview of the process is not a validated process.
Sources word surface growth differently. NCHFP's Dill Pickles page (https://nchfp.uga.edu/how/ferment/recipes/dill-pickles/) says to remove surface scum or mold promptly from fermenting pickles. Penn State Extension says not to taste kraut that shows mold. The Humboldt and Del Norte Master Food Preservers (UC Cooperative Extension) say white scum on kraut is from yeast, should be removed daily, and is no reason to discard the kraut.
Use salt without iodine or anti-caking additives. University of Minnesota Extension says iodine can interfere with fermentation, and Illinois Extension recommends additive-free salt. The same weight of salt fills a different volume for each salt type, so weigh the salt.
Do not ferment in copper, iron or galvanized metal containers or in lead-glazed crocks (Illinois Extension's fermentation handout, https://extension.illinois.edu/sites/default/files/fermentation_handout_2020.pdf, and Penn State Extension's sauerkraut publication, https://oc4h.ucanr.edu/sites/default/files/2020-10/337943.pdf). University of Minnesota Extension says to avoid metal containers because the metal reacts with the lactic acid.
Fermentation times for red cabbage are the NCHFP sauerkraut times for shredded cabbage (70 to 75°F, 3 to 4 weeks; 60 to 65°F, 5 to 6 weeks). They are not written for red cabbage alone. The other vegetables in this calculator use 68 to 72°F and 60 to 67°F bands from University of Minnesota and Illinois Extension general guidance, so the bands differ because the sources differ.
The Dietary Guidelines for Americans recommend that adults limit sodium to less than 2,300 mg per day. Brined and fermented food contains added salt.
Salt percentage
Red cabbage is dry-salted: the salt is a percentage of the cabbage weight, and the cabbage makes its own brine. The calculator offers two settings.
| Strength | Salt percentage | Salt per pound of food | Time at room temperature |
|---|---|---|---|
| Standard, 2.25% Salt at 2.25% of the cabbage weight, the low end of the 2.25% to 2.5% that two extension publications give for cabbage. | 2.25% of food | 10.2 g (0.36 oz) 1 Tbsp Diamond Crystal kosher 2 1/4 tsp Morton kosher 1 3/4 tsp Table salt | 21 to 42 days |
| Upper, 2.5% Salt at 2.5% of the cabbage weight, the upper end of the 2.25% to 2.5% range that Virginia Cooperative Extension and the University of Wisconsin-Extension give. NC State Extension lists salt over 2.25% as a cause of pink sauerkraut. | 2.5% of food | 11.3 g (0.4 oz) 1 1/2 Tbsp Diamond Crystal kosher 2 1/4 tsp Morton kosher 2 tsp Table salt | 21 to 42 days |
Weigh the salt when you can. The same volume of different salts weighs different amounts.
Virginia Cooperative Extension and the University of Wisconsin-Extension both give 2.25% to 2.5% of the cabbage weight, which the calculator uses at both ends. NC State Extension lists salt over 2.25% as one cause of pink sauerkraut. The Humboldt and Del Norte Master Food Preservers give 2% to 2.5%, and University of Vermont Extension gives 1.5% to 2.5%. NCHFP gives 3 tablespoons of canning salt per 5 pounds, about 2.4%, and 3/4 cup per 25 pounds, about 1.9%.
Salt and time by weight
Weigh the cabbage after trimming and shredding, before adding the salt. NCHFP gives amounts for batches of about 5 pounds and for 25 pounds. Enter your own weight in the calculator.
| Vegetables | Salt by weight | Diamond Crystal kosher | Morton kosher | Table salt |
|---|---|---|---|---|
| 2 lb (0.91 kg) | 20.4 g (0.72 oz) | 2 1/2 Tbsp | 1 1/2 Tbsp | 1 Tbsp |
| 5 lb (2.27 kg) | 51 g (1.8 oz) | 3/8 cup | 3 1/2 Tbsp | 3 Tbsp |
| 10 lb (4.54 kg) | 102 g (3.6 oz) | 3/4 cup | 1/2 cup | 3/8 cup |
| 25 lb (11.34 kg) | 255 g (9 oz) | 1 7/8 cups | 1 1/8 cups | 7/8 cup |
Weigh the salt when you can. The same volume of different salts weighs different amounts.
| Room temperature | Time |
|---|---|
| 60°F (16°C) | 35 to 42 days |
| 70°F (21°C) | 21 to 28 days |
The same volume of different salts weighs different amounts, so weigh the salt. The kosher salt versus table salt guide explains why.
What the time is based on
The times are the NCHFP sauerkraut times for cabbage, not written for red cabbage alone. At 70 to 75°F (21 to 24°C) NCHFP says kraut is fully fermented in about 3 to 4 weeks, which the calculator shows as 21 to 28 days. At 60 to 65°F (16 to 18°C) it may take 5 to 6 weeks, shown as 35 to 42 days.
Penn State Extension says fermentation at 60 to 65°F (16 to 18°C) may take 6 weeks, where NCHFP gives 5 to 6 weeks, and the calculator keeps NCHFP's figure. The University of Wisconsin-Extension says small jar batches usually take 2 to 3 weeks. The calculator uses the longer minimum.
Steps
- Shred and weigh. Shred the cabbage after trimming, then weigh it.
- Salt. Weigh the salt for your weight of cabbage.
- Pack. NCHFP says to mix the salt in with clean hands and pack firmly until the salt draws out juice.
- Cover. The cabbage must be fully covered by 1 to 2 inches of juice, according to the University of Wisconsin-Extension. NCHFP uses a plate and weights under a clean towel.
- Ferment. Keep the cabbage between 60 and 75°F (16 and 24°C), as the bands above show.
- Check. NCHFP says to check a jar-weighted crock 2 to 3 times each week and remove scum if it forms.
- Refrigerate. NCHFP says fully fermented kraut keeps tightly covered in the refrigerator for several months.
Safety
The brine food safety guide collects the limits that apply to every ferment.
Warning
NCHFP says to keep kraut at 70 to 75°F (21 to 24°C). Below 60°F (16°C) it may not ferment, and above 75°F (24°C) it may become soft. America's Test Kitchen ferments kraut at 50 to 70°F (10 to 21°C) and says that above 75°F (24°C) food safety becomes a concern.
Warning
Discard the ferment if it is slimy or smells spoiled or rotten (Illinois Extension). NCHFP's Dill Pickles page says to discard fermented pickles that become soft, slimy or develop a disagreeable odor.
Warning
Press the salted vegetables down and weigh them so they stay under the juice they release for the whole ferment. Vegetables that stick out of the liquid are exposed to air, which lets mold and yeast grow.
Warning
Do not reduce the salt below the amount shown. The National Center for Home Food Preservation says salt is vital to the safety and texture of fermented vegetables and not to cut back on the salt required, and the Inyo-Mono Master Food Preserver Program (UC Cooperative Extension) says it is unsafe to reduce salt in lactofermented vegetables.
Warning
Fermenting is not canning. This calculator gives no canning instructions. Do not can the fermented result unless you follow a tested canning procedure from the National Center for Home Food Preservation or a university extension service.
Note
The Humboldt and Del Norte Master Food Preservers (UC Cooperative Extension) say salt under 1.5% lets the cabbage rot, under 2% can give soft or slimy kraut, and over 3.5% may inhibit the lactic acid bacteria. The University of Wisconsin-Extension says too much salt slows fermentation and can cause an acrid flavor, darker color or pink yeasts. NC State Extension (https://content.ces.ncsu.edu/pickle-and-pickle-product-problems) lists salt over 2.25% as one cause of pink sauerkraut, along with unevenly distributed salt and kraut that was not covered or weighted during fermentation, and it calls pink sauerkraut unsafe. The 2.25% strength is at that figure and the 2.5% strength is above it, although Virginia Cooperative Extension and the University of Wisconsin-Extension accept 2.5%.
Note
If the juice does not cover the cabbage, NCHFP says to add a brine of 1 1/2 tablespoons of salt per quart of water, boiled and cooled. University of Alaska Fairbanks Extension says the cabbage should be covered with 1 to 2 inches of its own juice.
Note
University of Minnesota Extension says a ferment is ready when the pH is 4.60 or lower and bubbling has stopped. UC Davis says the pH must be below 4.6 to prevent botulism and that its overview of the process is not a validated process.
Note
Sources word surface growth differently. NCHFP's Dill Pickles page says to remove surface scum or mold promptly from fermenting pickles. Penn State Extension says not to taste kraut that shows mold. The Humboldt and Del Norte Master Food Preservers (UC Cooperative Extension) say white scum on kraut is from yeast, should be removed daily, and is no reason to discard the kraut.
Note
Use salt without iodine or anti-caking additives. University of Minnesota Extension says iodine can interfere with fermentation, and Illinois Extension recommends additive-free salt. The same weight of salt fills a different volume for each salt type, so weigh the salt.
Note
Do not ferment in copper, iron or galvanized metal containers or in lead-glazed crocks (Illinois Extension's fermentation handout and Penn State Extension's sauerkraut publication). University of Minnesota Extension says to avoid metal containers because the metal reacts with the lactic acid.
Note
Fermentation times for red cabbage are the NCHFP sauerkraut times for shredded cabbage (70 to 75°F, 3 to 4 weeks; 60 to 65°F, 5 to 6 weeks). They are not written for red cabbage alone. The other vegetables in this calculator use 68 to 72°F and 60 to 67°F bands from University of Minnesota and Illinois Extension general guidance, so the bands differ because the sources differ.
Note
The Dietary Guidelines for Americans recommend that adults limit sodium to less than 2,300 mg per day. Brined and fermented food contains added salt.
Problems and what causes them
Soft kraut. The University of Wisconsin-Extension lists insufficient salt, high fermentation temperatures, uneven salt distribution and air pockets from poor packing. NCHFP says kraut may become soft above 75°F (24°C).
Pink kraut. The Wisconsin publication says pink kraut comes from pink-pigment yeasts growing on the surface, more likely with too much salt, unevenly distributed salt or inadequate covering. NC State Extension lists the same three causes (salt over 2.25%, unevenly distributed salt, and improper covering or weighting) and calls pink sauerkraut unsafe. Dark or off-color cabbage. Virginia Cooperative Extension says pink, brown or black kraut is caused by spoilage organisms growing in the presence of oxygen, usually because the brine does not cover the cabbage, or because the fermentation temperature is high. It does not mention red cabbage.
Scum on the surface. The sources differ, as the surface growth note shows. The Wisconsin publication says to skim film yeasts or molds daily and remove discolored kraut within the top inch.
Related guides
Fermented Brussels sprouts use a kraut-style recipe with brine, and kimchi salt ratio covers another cabbage ferment. The fermentation salt percentage chart compares strengths across vegetables, and how to ferment vegetables covers the shared method.
Red cabbage calculator
Enter your own weight, salt level, choose your salt type, and get the salt by weight and volume and the time.
Open the red cabbage calculatorFrequently asked questions
How much salt do I need for fermented red cabbage?
The calculator's default is 2.25% of the shredded cabbage weight, which is 51 g (1.8 oz) for 5 lb (2.27 kg). The upper setting is 2.5%, which is 56.7 g (2 oz) for 5 lb. Both are figures for cabbage in general, since no source opened gives a recipe for red cabbage by name.
How long does red cabbage take to ferment?
The calculator shows 21 to 28 days at 70 to 75°F (21 to 24°C) and 35 to 42 days at 60 to 65°F (16 to 18°C). These are the National Center for Home Food Preservation's sauerkraut times for cabbage, not times written for red cabbage.
Is the salt ratio different from green cabbage sauerkraut?
The sources opened do not separate red cabbage from green cabbage, so the calculator uses the same cabbage figures for both. Virginia Cooperative Extension names cabbage varieties it says are better for sauerkraut and calls mature heads with a solid, white interior most desirable. It does not mention red cabbage.
Do I add water to fermented red cabbage?
Not at first. The cabbage is salted and packed until the salt draws out its juice. If the juice does not cover the cabbage, NCHFP says to add a brine of 1 1/2 tablespoons of salt per quart of water, boiled and cooled.
Can I can fermented red cabbage?
No canning instructions are given here. Fermenting is not canning, and you should not can the result unless you follow a tested canning procedure from the National Center for Home Food Preservation or a university extension service.
Sources
- Sauerkraut (National Center for Home Food Preservation)
- Vegetable Fermentation, FST-328 (Virginia Cooperative Extension)
- Make Your Own Sauerkraut, B2087 (University of Wisconsin-Extension)
- Sauerkraut (Master Food Preservers of Humboldt and Del Norte Counties, UC Cooperative Extension)
- Sauerkraut DIY (University of Vermont Extension)
- Pickle and Pickle Product Problems (NC State Extension)