Updated October 2026

How to Make Sauerkraut Safely: Salt, Temperature and Time

Cabbage, salt and three to six weeks. The two things that keep it safe are the right amount of salt and a kitchen below 24°C.

Mix 45 ml of pickling salt (3 US tablespoons, or just over two 20 ml Australian tablespoons) through every 2.25 kg of finely shredded cabbage, pack it down until its own brine covers it, weigh it under the brine and leave it at 21 to 24°C for 3 to 4 weeks. Those are the USDA's tested amounts and times. Do not cut the salt: it holds back spoilage bacteria while the lactic acid bacteria get going. In much of Australia the harder part is temperature, because above 24°C kraut turns soft.

Salt calculator

Weigh the shredded cabbage. By weight, the USDA amount works out at roughly 2.25 to 2.5% salt with fine pickling salt.

Step by step

1. Use fresh cabbage. USDA advises shredding within 24 to 48 hours of harvest. Pull off the outer leaves, quarter, core and shred it about 2 mm thick.
2. Salt in batches. Work 2.25 kg at a time. Mix in the salt with clean hands and pack it firmly into the container until the juice rises.
3. Keep it under. The cabbage needs to sit 2.5 to 5 cm below the brine. A plate weighed down with water-filled jars works, or a sealed food-grade bag filled with brine (USDA uses 68 ml of salt in 2.8 litres of water) so a leak will not dilute the kraut.
4. Top up if needed. If the juice does not cover the cabbage, add brine made from 22 ml of salt per 950 ml of boiled and cooled water.
5. Cover and wait. A clean towel over the top keeps insects out. If you weighted it with a brine bag, leave it alone until the bubbling stops. If you used jars as weights, check two or three times a week and skim any scum.

Temperature and time in Australian kitchens

Brisbane, Darwin and Perth kitchens sit above 24°C for months, so make kraut in the cooler months or in the coolest room you have. Cabbage is a cool season crop in most regions anyway, so the glut and the right weather tend to arrive together. A Hobart or Canberra kitchen in July can fall below 15°C overnight, so find a warmer cupboard.

Containers and cleaning

Allow about 4 litres of container for every 2.25 kg of cabbage. Australia's Food Safety Information Council advises glass or food-grade plastic and warns against ceramic, because some glazes contain lead; a stoneware crock sold for fermenting is the exception most fermenters rely on. Avoid metal other than stainless steel. Clean everything, then sanitise it with boiling water for 60 seconds, or a 10 minute soak in 1½ teaspoons of household bleach per 5 litres of water.

Scum, mould and when to throw it out

A white film on the brine is common; USDA's instruction is to skim it off as often as needed. Fuzzy mould on the surface should also come off promptly. If the kraut underneath is soft, slimy, dark or smells rotten rather than sour, throw out the whole batch. If mould has spread over the surface or you are unsure, throw it out.

Other fermented vegetables

Sauerkraut and fermented dill cucumbers are the two vegetable ferments with USDA-tested methods. Kimchi, brined carrots, beans and chillies are popular, but we have not found a tested Tier 1 method for them, so we do not give recipes here. If you make them, the Food Safety Information Council's advice applies: follow a trusted recipe's salt, temperature and time exactly, measure the salt, keep everything submerged, and refrigerate once sour. Never ferment meat at home.

Storing kraut

Fully fermented sauerkraut keeps several months in the fridge in a covered container. To keep it in the cupboard, process it: bring the kraut and its juice slowly to the boil, pack into jars with 1.25 cm headspace and boil them 10 minutes for jars up to 473 ml or 15 minutes up to 946 ml (up to 300 m above sea level). Heating kills the live bacteria, so keep some in the fridge if that is why you make it.

Sources we checked (October 2026): Food Safety Information Council, Fermenting food and drink at home (August 2019); USDA Complete Guide to Home Canning (2015) through the National Center for Home Food Preservation: Sauerkraut, General Information on Fermenting, Suitable Containers, Covers and Weights for Fermenting Food, Causes and Possible Solutions for Problems with Fermented Pickles; our AU regional planting data.

Common questions