Tag Archives: mother sponge

Baking Tales: Meet “Barm,” The Sourdough Starter

I spent the weekend making bread, bread and more bread! I’m working from the cookbook “The Bread Baker’s Apprentice,” which is by far the best book I’ve ever used for making bread. The instructions are crystal clear and all of my breads thus far have turned out beautifully. Plus, Peter Reinhart, the author, includes a variety of techniques for shaping beautiful loaves.

But before I get ahead of myself, I’d like you to meet “barm,” the newest member of my pet family (in addition to barm, we have two cats and a dog). Barm is a culture of wild yeast and bacteria used for making sourdough breads. Every fourth day or so, barm gets a feeding of fresh flour and water and goes crazy, bubbling away in its container. (Check out barm at right!).

Many people assume that what makes sourdough sour is the wild yeast. The sourness actually comes from the lactic acid bacteria that feed on the byproducts of the yeast fermentation. Commercial yeast usually cannot survive in this sour medium, but the wild yeast can, which is why this is such a symbiotic relationship. The yeast fermentation is usually faster than the bacterial one, so it takes time to develop the unique sour flavor we associate with sourdough; I’ve been nurturing barm (others call this the “starter” or “mother sponge”) for weeks now and it has developed a really nice complex taste.

Why does sourdough taste different from place to place? Wild yeast — present in the air and naturally in flour — varies quite a bit from location to location, which is why my sourdough will always taste different than San Francisco sourdough or New York sourdough.

Baking bread, by the way, is much, much easier than most people envision. Although many recipes call for an exact fermentation time, I’ve found that I can create the dough, leave it in a warm place and go work out or read for a few hours before coming back to a beautifully risen dough.

If you want to start your own barm or “mother sponge,” beware that it takes days before you can use it for your sourdough. The recipe is in “The Bread Baker’s Apprentice.” It’s pretty low-maintenance, but takes its time to develop the flavors you are looking for. You can also get free starter from a group called “Friends of Carl,” which has saved starter from 1847! Check it out at


Posted by on April 28, 2008 in Breads, Food Reads


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