Yeast Farming: Sourdough 1

Yeast. Single celled fungi. Amazing little beasts. They give us beer and wine and bread, without which much of civilization might not have happened. At least it would have happened much differently. We've been using yeast for well over 4,000 years, but we've only known that they exist since Anton Von Leeuwenhoek and his microscope first saw them in 1680. Before then brewers and bakers just knew that they had to keep a little bit of the last project around to fire up the next one. Some people consider yeast the earliest domesticated organism. The first thing we farmed, we couldn't even see.

I think I'm going to need a smaller tractor. 

Before 1780 you couldn't buy yeast to bake bread. You had to capture it yourself in the wild or beg or borrow or steal someone else's. Everybody's yeast is the same, and it's a little different. A big part of that is because the collection of microscopic stuff that lives in your house is different than what lives in mine. The yeast is specially adapted to your climate. That's one reason that San Francisco sourdough is so good, their local wild yeast is awesome. The more you bake, the more yeast you have just hanging around. Flour, fruit, sugar, it's all food to yeast. The natural variety, and convenience, is what initially let people to desire commercial yeast. They wanted bread to be consistent. Consistent from house to house, bakery to bakery, and season to season. Remember, baking wasn't always considered as much fun as it is now. Raising yeast is much more like very very small scale farming than baking. It's a bit of a pain in the ass.
With that in mind, a lot of bakers wish to try baking sourdough bread. It's considered somehow more magical than regular yeasted bread. To be a true baker, you raise your own yeast. Really though, sourdough is nothing more complicated than using wild yeast instead of domestic yeast. Imagine buffalo instead of cows. Capturing and raising a sourdough culture isn't much more difficult than keeping, and cycling, a flour and water mixture until a large enough population forms. There's already a few yeast in your flour, a few in the air, a few on the counter, you just need one of them and time. This article is as good as any at describing how to capture and raise your yeast. I've used his method with success. I've also used a method that utilized fruit juice or vinegar to make your yeast farm more acidic. The idea is to promote an ideal environment for your yeast to grow. I'm also a month into trying a method that I haven't read about but I doubt is new. I'm trying to colonize a batch of domestic yeast with wild yeast.
Normally, when I make pizza or bread, I use a poolish. It's nothing more than a fake sourdough starter. I mix yeast and flour and water and let it sit overnight to make the equivalent of a sourdough sponge. Except it's not sourdough, because the yeast are wrong. It's still delicious, but not the same. That got me to wondering. When you make a sourdough sponge, you just save a bit of it out, mix it with some flour and water and save it. That's you're starter for next time. What if I did that with my domestically yeasted sponge? Would I just continue to grow the same yeast over and over, or would the local wild yeast infiltrate the starter and take it over? It was clearly already an ideal environment to grow yeast in. So that's what I did. It seems to be working. My bread is changing with every loaf even though the recipe is staying the same. The flavor is changing and the texture of the bread is changing. It's getting really really aromatic and chewy. I really wish I had Von Leeuwenhoek's microscope and the knowledge to be able to watch my little yeast farm evolve. For now though, it's just as much magic as it was for thousands of years of baking. Save out a little piece of dough, take care of it, and make good bread next time.