I praised natural leavening (sourdough) the other day for its slow, deliberate rising. Having made quite bit of sourdough bread over the last week, I found the pace gave me time to implement some dough-stretching techniques I’ve long heard about but never tried. What’s dough stretching? It’s pretty much as it sounds, a process by which you gently tug your dough into an elongated shape as it rises, and then fold it or roll it back up into a lump and let it rise some more. You generally start the stretching at about the two hour point after mixing your sourdough, after the dough has had a chance to bulk up some. You stretch the dough every hour or so until it’s ready to be shaped (i.e. where you can really see bubbles when you cut into it). If this sounds familiar, it’s just that it’s a more refined variation on the “punching down” step we all hear so much about in our bread recipes. Yet simply de-gassing a dough doesn’t take full advantage of what’s occurring in the rising stage.
So what does stretching do? Two things that I can think of. First, it distributes the yeast throughout the dough. I know what you’re thinking: isn’t the yeast distributed already? I mean, we mixed and kneaded the stuff, didn’t we? Well yes, but yeast has a funny way of growing that requires you to spread it out every so often. We all imagine little microbial critters as being highly mobile, probably as a result of science class where we got to watch paramecium wiggle around under a microscope. But yeast really aren’t that kind of animal. They don’t have appendages (little cilia or pseudo pods or anything like that), so they don’t move. They grow by budding, making little offshoots of themselves which tend to stay very near (or on) the original yeast bud. Stretching the dough spreads them out, which gives the new little yeast buds an opportunity to find more food and create more little bubbles of carbon dioxide gas. Second, it stretches and elongates any bubbles that are already there.
All in all, the effect is a more open, holey crumb. Depending on how slow your starter leavens your loaf, you can stretch a sourdough like this up to half a dozen times. Or so I’m told, I’ve never had the courage to let dough rise so darn long. But the theory is sound. So far it’s worked. Try it yourself and see.