I am building a spreadsheet to help me develop formulas for breads. I'm gaining a much better understanding of baker's math in this process. However, I am getting some discrepancies in my calculations that I just can't seem to understand. I'm looking for help.

As an exercise, I'm working with a dough with the following parameters:

My spreadsheet calculates the amount of levain I need and how I should feed it. Another part of the spreadsheet calculates the amounts needed of each ingredient, including the levain. These two calculations of the levain amount are yielding different answers. I can't figure out why. 

Can anyone explain why the Final Dough says I need 210.53 gms of levain, while the Levain calculations says I need 240 gms of levain?

Thanks in advance.

David

From time to time I read posts with questions like this:

"I want to use 435 grams of starter at 70% hydration in a bread dough formula that calls for 500 grams of flour at 60% hydration.  How do I figure out how much flour and water I need to add in order to meet that requirement?"

Here's a primer that should alleviate the headache you might normally experience trying to figure it out.

435 grams starter at 70% hydration means you'll divide 435 by 1.70 for a total of 256.  That means 256 grams of your starter is flour.  Now subtract the known flour weight from the total starter weight and you'll get 179 grams of water.   So your 70% hydrated starter is the product of 256 grams of flour and 179 grams of water.

The bread formula you're working with calls for 500 grams of flour with a 60% hydration level.  So all you have to do is make up the difference between the 256 grams of flour in your starter and the 500 total you need for the bread (500 minus 265 equals 244) and add that much new flour to the mix.  60% hydration for 500 grams of flour requires 300 grams of water.  You already have 179 grams of water in your starter, so all  you need to do is add another 121 grams of water and you've achieved your goal.

Total Starter Weight/Hydration Percentage (as a decimal) = weight of flour content

Total Starter Weight minus Flour content weight = weight of water in the starter

The principal applies, regardless of the hydration level of the starter.  Of course, for an 80% hydrated starter, you'd need to change the hydration percentage figure from 1.70 to 1.80 to identify the comparative weight ration of flour to water in your starter.

Ok, so I'm pretty good at math. I had to get by to get through graduate and medical school. But, I'm seeing recipes with 448.5% of total ingredients? How does that work? Also, how do you figure out the hydration of your starter? What is the difference between a levain and starter as far as the percentage in hydration? Can I convert a starter to a levain? How do I figure the amount of water/ flour used by my starter or levain when making a recipe if the recipe is not properly done with percentages?

Are there any "rules of thumb" for the ratio/relationship of bulk fermentation time to final proofing times? 

For fast, straight doughs, I've generally found that the amount of time needed for the final proof is about half as long as for the initial bulk fermentation.  Now that I'm experimenting with the "yeast and time equation" to convert recipes to slow ripened ones, I'm beginning to wonder about this relationship.  If I convert a recipe to a 12 hour bulk fermentation, does that mean that I should plan on a 6 hour final proof? 

The yeast and time equation that I am referencing is from this post: http://www.thefreshloaf.com/node/10876/long-slow-bulk-fermentationplease-critique-recipe  and the ensuing discussion on same at the A Year in Bread site:  http://ayearinbread.earthandhearth.com/2009/02/math-is-not-hard-adjusting-yeast-for.html

Somehow my mind wanted to think that the yeasties were happily and languidly breeding during bulk ferment and that the final proof should be similar to a straight dough.  Not sure where I got that idea.  Is this concept totally absurd?

I'd been happily baking whole grain hearth loaves and other crusty breads when my husband dropped the bomb that he really prefers a sandwhich style loaf for morning toast.   So I tied out the ZolaBlue's Semolina sandwhich loaf  http://www.thefreshloaf.com/node/4213/semolina-sandwich-loaf .  I didn't have any semonlina flour on hand, so I used spelt flour as the closet item to durum flour in my pantry.  The loaf was delicious although I did not get quite the same ovenspring with the whole grain spelt flour.  I tried agan with semolina flour but reduced the yeast to 1/8 tsp for a 12 hour bulk rise. (I prefer the taste and digestibility of a long ripened dough for our staple bread).   It actually took 18 hours to double in the bulk stage, but only 3 hours to double in the proofing stage.

I am currently using the same basic proportions as the Semolina Sandhwich loaf but with a mix of White Whole Wheat (WWW) and whole grain spelt flours, using butter instead of the olive oil.  The dough doubled nicely in the 12 hour bulk stage but looks like it will need 6 hours to double in the final proof.  It's been in the oven with the oven light on for 5 hours now.  I've been refreshing the pan of boiling water in the oven to keep it humid in there.  The dough is just now cresting above the loaf pan.  I'm guessing another hour before I can bake it.  My main driver on the 12 hour bulk timing is to fit the baking in with my schedule.  I mix up the dough at night, shape it after breakfast.

Any thoughts on the time ratio between bulk and final proof times?  Anyone have similar or alternate experiences using the yeast and time conversion?

I put together an Excel workbook for working with bread formulas. Although there are other similar tools on this site, this one has some nice additional features. Let's say you have a formula for a sourdough bread, but you want to make a couple changes. First, you want to add 10% spelt flour, you want to up the hydration from 65% to 68%, change the salt form 1.8 to 2%, reduce the dough yield from 3.5 pounds to 3.0 pounds, and increase the percent of pre-fermented flour from 15-20%.