The Science of Sourdough

Many readers have expressed an interest in Tituba, my sourdough starter. I started her sometime in the 1980s and really don’t know how old she is. One of the secrets is knowing how to put her away for long term storage. I used to freeze a small sample, but these days I dry the sample and refrigerate.

A sourdough starter is a wild yeast culture, but that’s pretty simplified. They really don’t travel all that well, and will eventually become a culture of your local wild yeast. That’s why I never feared adding other yeasts to the mix.

Active dry yeast is the hothouse flower of the yeast world. It will only last a generation or two under the crock environment. Its best use is to medicate an ailing starter, knowing it will all disappear and leave your wild beastie in place. I’ve added champaign yeast, brown ale yeast, and active dry yeast to mine at times.

The lifespan of one yeast organism is somewhere around the blink of an eye. I have no doubt that some hybridization occurred, but Darwinism leaves me with a decent starter. She was born in Nevada, and may be more of an Idaho wild yeast these days.

There is a microscopic war going on all around us. We want yeast to leaven our bread, but yeast is under a constant attack. The enemy here is mold. Tituba needs an ally.

Enter lactobacillus. This simple bacteria hates and kills mold with extreme prejudice. It loves the alcohol produced by the yeast as it devours the flour I feed it. I get bubbles that raise my dough, and the bacteria gets the waste product of fermentation, alcohol. (Every military in history thrives on alcohol.) The bacteria in exchange, keeps the mold at bay.

But wait, there’s more. Sourdough bread has a distinct tangy flavor. This flavor isn’t available to bakers who use active dry yeast. That’s right, it is provided by the lactobacillus.

Tituba is a symbiotic organism. She consists of both a wild yeast culture, and a colony of lactobacillus. She makes great bread too.

I baked my first loaf of the year this morning. It turned out great. I left it out overnight to ramp up the sour flavor. The house is usually cold enough at night, but this time it over proofed a bit. It was about to crawl out out of the Dutch oven when I got up. It fell a bit when I sliced the dough prior to baking. Still, it tastes wonderful.