Some days ago I had to sent some sourdough per mail. That is easy when the sourdough is mixed with a lot of flour to form dry crumbs – the German name for this is “Krümmelsauer” while it is called “Gerstl” in Austria. The crumbs should be as dry and fine as possible. This reduce the amount of water and put the microorganisms to hibernation. In this state there is nearly no fermentation going on.
Reactivation is easy as well. Mixing the “Krümmelsauer” with water and waiting until the first bubbles are showing. And as I realised that I never showed this kind of sourdough conservation on the blog, I made a double batch. One halve I sent to Berlin, the other one I kept for three days on the counter to simulate the enviroment during mailing. Then I mixed the sourdough crumbles with water and as my sourdough is quite active I saw the first bubbles after one hours already. I let the mixture ferment for another five hours, then I used it to start a sourdough. And this sourdough doubled its volume easily overnight.