There are several ways to keep the beloved sourdough culture alive and well during periods of absence. On a commercial level, lab cultures are mixed, usually with rye flour to a semi dry crumble (struesel), and are packed and shipped world wide in kg. blocks, bakerys use these products to tuneup an existing culture or to begin afresh.
One month ago, i set about to try to duplicate this process.
I brought a portion of my culture to a state of vigour , mixed it with rye flour in a kitchen aid with the paddle attachment, at the point where the tiny machine started to complain about the stiffness, i took it further and incorporated more flour by hand in a bowl.
I then spread the crumb mixture on a screen to air dry for two days.
The crumb mixture is being stored in jars in a cool basement pantry.
So far i have successfully regenerated the culture twice and will continue to test this over the next few months.
Update, at the 3 month point the struesel culture was overtaken by mold, and was fed to the compost worms.