Drying and freezing sourdough starter

How to dry a starter

Label the jar with the date. Dried starter keeps for months; many bakers keep one as insurance against mold or a forgotten jar.

1. Feed the starter and use it at its peak.
2. Spread a few spoonfuls paper-thin on parchment or a silicone mat.
3. Leave it to dry at room temperature, away from sun, until it snaps: a day in a dry, warm house, up to five days in damp weather (King Arthur).
4. Break it into flakes or grind it coarsely.
5. Store in an airtight jar in a cool, dark cupboard.

Reviving dried starter

Soak the flakes in twice their weight of lukewarm water until they dissolve, about 3 hours with an occasional stir, then stir in flour equal to the flakes' weight and keep it warm (King Arthur's method). Feed 1:1:1 twice a day. Expect little for a day or two, then rising; it is ready when it doubles within 4 to 8 hours, as in when is my starter ready. If the revived starter grows fuzzy mold or pink or orange streaks, or smells of anything but sour or alcohol, throw it out and revive another spoonful of flakes (when to throw a starter out).

Freezing

King Arthur advises against freezing a starter: its drying guide says freezing will kill it, and its troubleshooting guide says a brief freeze may be survived but a long one does damage. Dry a spoonful instead.

Travelling with a starter

For a few days, feed a stiff starter, keep it cool in a jar with room to rise, and feed it on arrival. For longer, take dried flakes. A jar with a loose lid matters on the road: an active starter makes gas.