September 24, 2023 - 3:15pm
Is the loss of mass flour as well as water?
I typically lose about 6% mass making a levain. I have always assumed this was almost completely evaporation. But how much of the loss is flour that gets converted to gas via the chemical and biological processes of fermentation?
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I don't know the answer, but when I make my standard mostly-white sourdough loaves for which I don't build a levain but just use my mother culture directly, 20 oz of flour will produce two 1-lb loaves. This would be around 70% hydration plus say 3 oz of starter, So 37 oz of dough would end up as 32 oz of baked bread, for a 17.5% weight loss overall.
(Not sure if this is helpful!)
TomP
Flour mass loss is about 2.3-3.8% during preferment stage alone. Basically, it's flour sugars digested by microorganisms. They consume about 5% of sugars from start to finish (from mixing preferment all the way to the end of proofing before baking) in a traditionally made yeasted bread.
I once read a dissertation on that topic where they added 5% sugar to the formula of a typical soft sandwich bread sold presliced in grocery stores in plastic bags and in baked bread tests showed little (about 0.5%) to no sugar present, it was all gone, digested by baker's yeast and bacteria in flour.
2.3-3.8% dry flour mass loss refer to a traditional yeasted or sourdough sponge fermented at 30-33C for four hours. Longer than that will lead to more dry mass of flour loss. Shorter duration of preferment's fermentation, or direct method and zero time doughs, and/or using liquid preferments instead of the stiff ones help reduce dry mass loss.
Very little water, alcohol, or organic acids evaporate during fermentation and proofing before baking. They are lost during baking (usually 6-12% or up to 25% and 50% of raw bread mass loss in French baguettes and fiicelles/ thin baguettes), and bread cooling (3-5% of baked bread mass) stages.
"Flour mass loss is about 2.3-3.8% during preferment stage alone. Basically, it's flour sugars digested by microorganisms."
"Very little water, alcohol, or organic acids evaporate during fermentation and proofing before baking."
Thank you!
1) I think in dry Az with less-than-perfect seal I may end up with some evaporation as well, and some tiny amount sticking to container I can't see. But the point is taken: in theory flour is the main loss.
I'm going to have to change my calculations for total flour in my formulas. I've been estimating the flour in the levain based on its dough hydration and amount of levain used. But if what you're saying it true it sounds like that over-estimates the flour amount!
2) Now I wonder why e.g. Hamelman and others using BBGA have formulas that take chef + flour + water over 12-16 hours, then take out the chef leaving the exact amount of flour and water in the final levain (with no loss). If one follows their methods of elaboration, wouldn't the levain be constituently about 1-2% too small at time of use, at least those with long final builds?
Personally I don't think it's worth worrying about 1-2% in home baking. Even if we can measure that precisely, and even if some of the liquid or dough doesn't stick to a container and get left behind, a small variation in amounts leads to a small variation in results. I mean, we don't know the age or water content of our flour, we don't know the nature of the micro-organisms in our starter or even if that composition is stable from week to week. We don't know how much the gluten content of our favorite flour varies from bag to bag - a change of 1% in a nominal value of 11.0% is only 0.11%, too small for a bag to be reprinted, I'm sure. We don't know the real falling number of this one batch of flour. Our room temperature surely varies by several degrees.
So I don't worry about tiny variations. Now if I ran a professional bakery, it would probably be different.