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Guidelines for converting yeast weights to equivalent starter weights???

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SpartanArtisanWantabe's picture
SpartanArtisanW...

Guidelines for converting yeast weights to equivalent starter weights???

Could someone provide some guidelines for converting yeast weights into active sourdough starter equivalents. That is if a recipe calls for 1/4 tsp of yeast how much starter should I use? My starter is home grown from wild grapes ala the La Brea starter and is quite potent. I keep it at 100% hydration ( I think that is right 8 oz flour 8 oz water) and I am trying to transform the acme rustic baguette recipe from Artisan Baking into a natural levain based recipe, knowing that I'll have to adjust the hydration levels to account for the starter. When making a preferment with 4 oz of starter, 8 oz of water and 11 oz of all purpose (i.e. cooks illustrated) and leave it sitting on the counter all night it seems like the yeast is spent. (Could this be why I get a pale crust no matter howlong I bake?), refrigeration helps but I'm getting forgetful in my old age and often go to bed with it on the counter.

SpartanArtisanWantabe's picture
SpartanArtisanW...

Okay as a relative newbie please forgive the non scientific nature of this experiment. Perhaps this should be on a different board??? I ran a little experiment today trying to figure out how much starter to use to replace the yeast in some of the recipes I would like to try.  In one glass I put 1 oz of my starter and enough flour and water to get to 1-5/8 oz water and 2.5 oz flour for what I thought would be a fairly typical hydration level.  In the second glass I put 1/4 teaspon of yeast and the same total amount of flour and water.  After 4 hours I got this first picture. The yeast is on the left. After 6 hours I got the second photo. The yeast is bubbly and soft about maxed out I think but the sourdough is catching up and still doming.  I wish I had taken a picture every hour or half hour. At three hours there was even more of a difference. The yeast expanded much more quickly and seemed to top out after about 4 hours. The sourdough appears to have nearly the same ability to raise the bread but takes half again as long to get there and comes up a little short but it was still working. Now after just over 7 hours they are at about the same volume. I am not sure what would happen if I used twice as much starter. Would it have surpassed the yeast and topped out earlier? Has anyone seen similar responses with breads they have made?


Yeast vs Sourdough after 4 hours


 


 


Yeast Vs. Sourdough after 6 hours

LindyD's picture
LindyD

Google came up with this - and a number of other hits:  http://www.sourdoughhome.com/convert.html


Hope it answers some of your questions.

SpartanArtisanWantabe's picture
SpartanArtisanW...

Thanks for your help. It seems like the answer I am looking for is that an ounce of healthy room temprature starer containes the equivalent of about 1/8 to 1/16th of a teaspon of yeast, I am sure there are some growth rates in there and maybe a math wiz could figure them out. I'm making lots of assumptions here but if it took roughly twice as long to double then maybe I started with about 1/2 of the population hence the 1/8. If the volume tripled then it would be closer to the 1/16th I think. The link suggests that starting with a cup of starter for a TBL spoon of yeast is about the right place to start. This seems close given what I saw.  8 oz of starter is close to a cup. I think a cup of my starter actually comes in at about 9 ounces and I get more like 2 1/2 teaspoons out of a package of yeast instead of a tablespoon, I'll start with the assumption that 1 ounce of starter is roughly equal to 1/8th of a teaspon of yeast, maybe a llittle less and see how things work out. Thanks again for your help!

LindyD's picture
LindyD

Susan of Wild Yeast has some interesting thoughts about such attempted conversions.

SpartanArtisanWantabe's picture
SpartanArtisanW...

Thanks for the link, it is interesting the bread photos are fabulous. Interesting that Susan starts with 15-25% Several of the recipes that I looked at from Nancy Silverton for example use about 30%.


There were several other things I noted in the little experiment I did. 1.) The whole family preferred the smell of the sourdough culture fermenting to the comercial culture, it smelled nutty and bready where as the comercial culture had an off oder to it especially in the beginning stages, By they time I threw them out they both smelled about the same neither one smelled bad just overly fermented. 2.) The wild yeast starter had the ability to expand the dough to the same level as the comercial yeast for some reason I was surprised by this but it makes sense when I think about it. Same food same limit on growth. 3.) The wild yeast culture seemed more forgiving. After 24 hours it was still light and bubbly, but the comercial yeast culture had completely colapsed.


I'm going to make my first pass at my own wild yeast baguette recipe this weekend we'll just have to see how it turns out and how to tweak it from there. Thanks again and have a great day!