Sam Sifton today had a great piece in the New York Times on sourdough cultures, showing how natural fermentation is going mainstream. For those who are interested, I spend a whole chapter explaining sourdough cultures in my book and the science behind it. Fascinating stuff. 

Here's a quick post I wrote some time ago on how to make a sourdough culture. (There is a much more detailed recipe in the book that readers have found very successful). The video that accompanies it uses rye flour.

Quick tips to keep in mind:

• Whole grains help jump-start the culture, because of minerals and other components in the bran.
• Keep the temperature warm, the ideal is 78-80 F. If your kitchen is cool in the winter it will be very hard to get the culture going.
• Start with acidic liquid, such as pineapple juice to start to favor the right organisms (they like an acidic environment). 
• Keep going even when the culture looks dead. It's alive.
• Sourdough is ready when it floats in room temperature water. Take a piece out to test it. Or rise a stiff ball of sourdough in the water itself. It will rise!