August 11, 2015 - 3:37am
water temperature formula for mixing sourdough and final dough in general
Lately I've thought a lot about the calculation for water temperature when you're mixing sourdough or the final dough to achieve the optimal temperature you want. The formula commonly used does not take into account the different ingredients' mass. So say if you have some sourdough starter from the fridge, the resulting water temperature from the formula will be greatly exaggerated to compensate for the starter's low temperature, even though the starter was only 10% of the flour mass.More subtly, the water itself may range between a very dry final dough (60%) to a very liquid leaven (125%). All things being equal, the water temperature should be different when the hydration level is different. I've worked out a new formula to take these things into consideration. This is described in a new post in my journal: http://www.thoughtfulness.co/journal/2015/8/11/work-out-water-temperature-for-bread-dough In short, the formula is:
Tw = Td - FF + (Mf(Td - Tf) + Mod(Td - Tod) + ΣM(Td - Ta))⁄Mwwhere T=temperature, M=mass, d=dough, f=flour, od=old dough, a=ambient, FF=friction factor. Let me know if you have any thoughts on this subject! I'm being a little obsessive about this because I recently overheated my starter slightly. Perhaps I'm just relying on these formulae and calculations too much :)
who have large volumes of dough and seek to control the fermentation conditions. What is missing from this equation is the heat transfer loss/gain from the sides of the bowl or container. It's also designed for doughs made in mixers and you won't have much of a friction factor if you are hand mixing the dough. Honestly, this is one thing I really don't pay much attention to (and I'm a chemist by training) as I don't bake commercial quantities of dough and have found that room temperature is really what dictates things (quicker in the summer, slower in the winter).
Yes, the ambient temperature is the most important element, as the dough temperature will always tend to that over time, which is why the ambient temperature is given the biggest weighting in the formula.
I agree with the friction factor point as I also hand mix my dough. I think of it as the fudge factor because sometimes I know the weather might turn nasty in the night and add a few degrees to the calculation. At the same time, a lot of home bakers use mixers too.
I find that in the normal range of temperatures, say 70 to 85F it makes much more sense to measure dough temperarure after the mixing and do the appropriate adjustments to the fermentation time. Forcing the dough into tight production schedule is something that commercial bakers have to do. At home, most of the time, it's easier to predict and follow the dough.
This is also a very good point. I absolutely love the weather in London right now because we are in that temperature range so I don't actually have to use my formula at all except for rye bread.
But in winter, my house is too cold. So as I have to mix in some warm water anyway, I may as well work out the best temperature as best as I can. Also, often I do have to follow a schedule at home so I can go out! And it is difficult for beginners to follow the dough as we have no idea what the dough should be like. So at least at the beginning, everyone needs some guide to get a feel for it.
What an equation! While I love the science behind the baking and the bread baking app I wrote has a dough temp calculator, it is nothing as complex as this... your equation kinda scares me ;)
Is your baking app available for download? You're very welcome to adapt my formula in your app. It's not so scary once you look into it. It's using all the information we already have for our dough.
By the way, your bread on the fresh leaf blog looks amazing!
Thanks for the reply and kind words on the bread. I actually will take another look at your formula. At this point I am still updating and testing the app, so it is not available. But I had coded an optimal dough temperature calculator in pretty early. I need to go back and look at what the formula actually was now, I have forgotten.
What about surface area and the storage material?
A metal bowl transfers heat much more effectively than a plastic one....
(So easy to go down the rabbit hole on these things!)