Substituting Bread Starters

[CobraLimes]

I'm trying to convert a recipe that uses a yeast-based starter into one using a sourdough starter. I am proofing the sourdough starter overnight. My question is what quantity sourdough starter do I use in place of the yeast-based starter?

The recipe calls for a starter made with:

1/2 cup water (75-F.)
1/2 teaspoon dry yeast
3/4 cup flour

and after it's proofed it calls for an additional 1/2 tsp. yeast.

Also, is there any need to use that additional yeast?

Thanks in advance. (I've posted this in Cooking Q & A, also)

[MEAN CHEF]

Sorry I never use sourdough starters only Bigas.

[justcallmejulie]

Check the first stickie in this thread.

[Donna M.]

Those quantities would equal 3/4 cup of starter. Leave out the yeast in both instances. You don't need it. Be aware that the flour to water ratio is different than what some starters are fed. If you are currently feeding with a 50/50 ratio you have a wetter starter than the yeast starter is.

My suggestion is that you remove 1/4 cup of starter from your starter pot and feed it with the 1/2 cup of water and 3/4 cup of flour. Measure out 3/4 cup of that mixture and use it for your recipe. Put the remaining small amount of starter back in your original pot.

Is that clear as mud?

[CobraLimes]

Thanks again, Donna, for your expertise. I wasn't able to get your answer prior to experimenting on my own. I proofed the starter overnight with a 1:1 ratio of flour and water, added the entire quantity of water called for in the recipe and omitted the yeast. Then I added about another full cup to 1 1/2 c. of flour (due to the consistency of the dough). It took a very long time to rise, and didn't rise as much as I thought it should, but once baked it literally blew up like a balloon and formed an absolutely gorgeous loaf of perfect bread. Next time I try this recipe I'll use your ideas (it will certainly save me in flour usage). You've taught me well and still continue to and I really do appreciate your help. Thanks!