Sourdough and Commercial yeast

Toast
bobku on 27 Oct 2011 at 11:19

I have seen quite a few recipes using both sourdough and comercial yeast together. BBA has some and I think it is usually done to speed things up, can these be safely converted to all sourdough by just incrasing the rising time or increasing the amount of starter, or are there other reasons for using commercial yeast

I don't know for certain, but many of the ones I've encountered use large quantities of sourdough starter as if they were using it less for its leavening capacity and more for the characteristic flavour it imparts when used in quantity. It's almost as if they're using the sourdough itself as a poolish or sponge, not for leavening, which is where the commercial yeast comes into play. In short, commercial yeast for the leavening power and sourdough starter for its flavour.

Nancy Silverton, for example, uses this method in her breads (very large quantites of sourdough + commercial (she used cake) yeast) to great effect. That she used both sourdough and commercial yeast did her no favors, as people are/were very critical of her method (and they are to this day). Most of them, in their purity, have likely never tried her breads because, if they had, they'd quickly find themselves silenced by mouthfuls of some really wonderful bread.

Q. If sourdough starter is used in quantity, then how can it not have an effect on leavening, a significant one?

Obvious question, right?

A. Most of the recipes retard these heavily "sourdoughed" doughs either for bulk, proof, or bulk and proof. Cold, being the nemisis of sourdough beasties, "retards" the leaving effects of the sourdough.

That seems right in my head but, again, I really don't know why for certain.

Yesterday I baked a batch of bread from a recipe that a friend sent me. It used 1.5 cups of starter and one packet of yeast (I used about 3/4 tablespoon of instant). I was surprised that it turned out with a thin, soft golden crust and a very airy crumb. Dare I say "Wonder Bread" soft? I used my potato flake starter and the taste was very, very good. My SO who doesn't like SD bread ate two big slices. Bob

I believe Reinhart(in BBA) tries to explain that there are many variations people use to make sourdough breads. Some bakers "spike" the final dough with yeast for predictability(and shorter rising/proofing times). Many prefer to go the "pure" sourdough route.

He has recipes using some of these various methods, but explains that you can use virtually any method for any recipe. Use whatever method you feel comfortable with, given your situation. He even says that if you have learned other methods, go ahead and apply those methods to his recipes.

I don't know which formulas you're looking at specifically, but I have done just what you suggest with a number of breads, some in the BBA and some elsewhere. I'm partial to a full sourdough bagel build. I've also incorporated starter into some straight doughs, e.g. BBA's semolina snail, pizza dough and multigrain loaf, as well as in a chocolate bread. My experience has been pretty positive, so long as you adjust the flour/water accordingly (very easy if you have a 100% starter), and are flexible on the rise times.

What Thomas said is correct.  You are essentially using the starter as a preferment to the final dough, adding flavor and giving a little extra rise. 

With that said, yes you can cut the yeast from the recipe, but you would most likely need a greater amount of starter in the recipe than before, or you would have REALLY long proof times.