Disclaimer

Last updated: May 2026.

Fermentation is one of the oldest food-preservation methods on Earth and, when handled with the right salt, the right temperature, and a bit of attention, it is also one of the safest. It is not, however, foolproof — and the recipes published on Ferment Foundry are written for adults who are willing to read carefully, follow numbers, and use their own senses.

Read this before you start

Every recipe on this site has been tested in our own kitchen, but your kitchen is not our kitchen. Ambient temperature, the mineral content of your water, the salt brand you use, the age of your starter, and the airflow around your jar all change the outcome. Treat the timings as guidelines and your own observations as the final word.

Specific risks worth knowing

• Botulism in low-acid environments. Clostridium botulinum spores cannot grow in sufficiently acidic or sufficiently salty conditions, but they can grow in oil-covered ferments such as garlic-in-oil and in low-salt vegetable ferments. Stick to a minimum of 2% salt by weight for most vegetable ferments and never store raw garlic in oil at room temperature.
• Mold vs. kahm yeast. Fuzzy, brightly coloured growth on the surface of a ferment is mold and the batch should be discarded. A thin, white, slightly wrinkled film is usually kahm yeast — harmless but bad for flavour. If in doubt, throw it out.
• Pressure. Second-fermentation kombucha, water kefir, and ginger bug sodas can build dangerous pressure in sealed bottles. Use thick-walled flip-tops, refrigerate before fully ripe, and burp regularly.
• Allergies and dietary needs. Many guides include soy, gluten, and dairy. Check ingredients against your own needs before you cook.

Not medical advice

Anything you read on Ferment Foundry about gut health, digestion, or the properties of fermented foods is general information, not medical advice. We are not doctors. Talk to a qualified health professional before changing your diet for any health reason.

Questions about safety on a specific recipe — email [email protected] and we’ll do our best to help.