Kombucha: what to know before you brew

Kombucha is an interesting drink to understand before it becomes a kitchen project. The useful questions are practical: what is changing in the tea, how is the process controlled, and what happens after bottling?

One culture, several changes

In sweetened tea, yeasts and bacteria work together. Sugar can become alcohol, and bacteria can use oxygen to convert alcohol into acid. Those changes do not move in lockstep: a tart drink is not proof that all its alcohol or sugar has disappeared. University of Georgia: Homemade kombucha

Acidity needs a method

Start with a tested brewing method that includes ingredients, quantities, timing, temperature, acidity checks and storage. Do not use “it tastes sour” as the whole acceptance test. Use a suitable food-grade vessel; acidic drinks can leach unwanted substances from unsuitable materials. University of Georgia: Homemade kombucha

Mould is a reason to discard

Dry, fuzzy patches on the culture or liquid surface are a spoilage sign. University of Georgia guidance says to discard both the tea and the culture, then clean and sanitise the vessel. Removing the visible patch and carrying on is not its recommended response. University of Georgia: Homemade kombucha

Bottling changes the job

A closed bottle can accumulate carbon dioxide. BCCDC guidance identifies excess pressure and continued alcohol production as hazards in raw kombucha; refrigeration is part of controlling the finished drink. Follow the chosen process's bottling and storage directions rather than extending a warm second fermentation for more fizz. BCCDC: Kombucha and jun guidance

Alcohol can rise after the drink leaves the fermenting vessel. The TTB explicitly addresses kombucha that continues fermenting after bottling. A homemade batch should not be assumed alcohol-free. TTB: Kombucha requirements

Choose a drink on its own merits

Enjoying the flavour is a clear reason to choose kombucha. A broad promise about gut health is a different claim and needs its own evidence. Our guide to probiotic claims explains what to look for.

If alcohol must be avoided, do not rely on an unmeasured home brew. BCCDC's guidance also flags kombucha as unsuitable for young children and during pregnancy. BCCDC: Kombucha and jun guidance

This overview is for choosing and understanding a project. Use the linked brewing guidance for a complete method; a diagram of fermentation is not a recipe.