The Omnivore's Dilemma: A Natural History of Four Meals

by Michael Pollan

Gathering wild yeast turns out to be no big deal. The spores of various yeasts are floating in the air just about everywhere; collecting them is a matter of giving them a place to rest and something to eat. Some species of yeast taste better than others, however, and this is where geography and luck enter in. The Bay Area has a reputation for its sourdough bread, so I figured the air outside my house would be an excellent hunting ground for wild yeast. I made a thick soup of organic flour and spring water (the idea is to avoid any chemicals that might harm your yeast); then, after briefly exposing the mixture to the air on a windowsill, I sealed it in an airtight container and left it out on the kitchen counter overnight. By the following morning the surface of the chef, as it’s called, was bubbling like pancake batter on a hot griddle, a good sign. Each day, you’re supposed to feed fresh water and flour to the young colony of microbes, and sniff it. The chef should smell slightly alcoholic, sour, and yeasty—a bit like beer. The absence of bubbles is a bad sign. So is the presence of off odors or colorful scums, which indicate you’ve probably snared wilder and weirder microbes than you want; throw out the chef and start over. I counted myself lucky that by the second day my chef already smelled promisingly beery and breadlike.