liquid levain question

[android]

i was trying to formulate some experimental recipes last night and was curious to know if there is a general conversion in regards to amount of "yeast" that should be added when using a sourdough for leavening rather than baker's yeast? for example, if i were to use .5% IDY, would there be any sort of translation, percentage-wise, into sourdough to experience similar dough properties (notwithstanding flavor of course)?

[Matthew]

i was trying to formulate some experimental recipes last night and was curious to know if there is a general conversion in regards to amount of "yeast" that should be added when using a sourdough for leavening rather than baker's yeast? for example, if i were to use .5% IDY, would there be any sort of translation into sourdough to experience similar dough properties (notwithstanding flavor of course)?

The range will vary based on fermentation time & the strength of the starter being used. 

[Pete-zza]

for example, if i were to use .5% IDY, would there be any sort of translation, percentage-wise, into sourdough to experience similar dough properties (notwithstanding flavor of course)?

android,

That is a question that comes up fairly frequently. It is possible to come up with a reasonable conversion of a dough formulation using commercial yeast to a natural sourdough format, and vice versa, but it will depends on the dough formulation, fermentation protocol, etc. You can see some of the challenges involved in Reply 92 at http://www.pizzamaking.com/forum/index.php/topic,11578.msg107295.html#msg107295. You can also see an example of a conversion I did for Norma at Reply 111 at http://www.pizzamaking.com/forum/index.php/topic,11578.msg107361.html#msg107361. In that case, I converted a basic Lehmann NY style dough formulation using commercial yeast (IDY) that Norma had been using into a preferment format using a natural starter culture (Ischia).

For background reading purposes, you might read the thread at http://www.pizzamaking.com/forum/index.php/topic,11578.0.html and the related thread at http://www.pizzamaking.com/forum/index.php/topic,11700.msg108007.html#msg108007. You might also read about Mike's Simplistic Conversion Technique at http://www.sourdoughhome.com/convert.html, which I tested in the assistance I provided to Norma, and also the article at http://www.nyx.net/~dgreenw/howdoiconvertyeastbreadrec.html. I have written fairly extensively on this subject in general, for several different pizza styles, from NY style to cracker style and just about everything in between, so if you do some forum searching you should be able to find other posts that I have entered on the subject.

Peter

[android]

wow, my search skills suck! thanks pete-zza, i for some reason couldn't find what i was searching for. i appreciate all the links and will read up. i ended up using 3.6% based entirely on what appeared like an appropriate amount to ferment the dough over a few days in the fridge.

[Pete-zza]

i ended up using 3.6% based entirely on what seemed like an appropriate amount to ferment the dough over a few days in the fridge.

android,

Member pizzanoletana (Marco) recommends using up to 5% of the total formula water when using a natural starter culture to make a Neapolitan dough. However, the fermentation is conducted in stages (bulk, followed by division) at ambient temperature, over a period of many, many hours. If you use 3.6% starter (presumably by weight of formula flour), you may find that the dough will not ferment sufficiently while in the refrigerator, even after several days. Moreover, you are also likely to end up with a gluten structure that is damaged by action of enzymes in the flour.

Peter