How to tell them apart
- Kahm yeast: a thin, flat, white or cream film. Wrinkled or tight-meshed, a little like a skin. It smells of alcohol, yeast or sour fruit. It sits on the surface and does not grow hair.
- Mold: fuzzy, dry or powdery, raised. Often in spots. White, green, blue, gray or black. Often smells musty.
- Pink or orange streaks or spots: a sign of unwanted bacteria. Throw the starter out.
- Dark liquid on top: not mold. It is hunger, often called hooch. Stir it in or pour it off.
What to do
- Mold or pink and orange streaks: throw out the starter and the jar contents. Do not scrape the top and keep the rest. Clean the jar thoroughly and start fresh.
- Kahm yeast: remove the film and a little of the starter below it, then feed as usual. If you are not sure whether it is kahm yeast or mold, treat it as mold.
- Do not sniff closely. Mold spores are not something to breathe in.
The rule that keeps you safe: when in doubt, throw it out. A new starter costs you a few days. It is not worth risking your health for it.
How to prevent it
- Feed on a steady rhythm so the starter does not stay hungry for long
- Use a clean jar and clean utensils
- Keep it loosely closed, not airtight, and not in a damp or very warm corner
- Look at the surface before every feeding
The Starter Kit includes a troubleshooting table that matches every symptom, including films and smells, to the right action. The Starter Colleague has a Help section with the same rule: when in doubt, throw it out.
Get the Starter Kit — €16