Desired Dough Temperature (DDT): further considerations
Desired DoughTemperature (DDT), at best only a gross-estimate of the temperature of a dough at the beginning of bulk fermentation (ref.: http://www.thefreshloaf.com/node/11719/ddt-calculation-question-daniel-t-dimuzio ) is too often ignored, or given only a brief word or two of non-specific, and often ambiguous explanation. (See, for example, BBA's Pain a l'Ancienne: this is the best I've found, and still, in my opinion, using ice-water is ambiguous in specificity, and lacks complete explanation, of effects and side-effects.)
Within the usual range of factors, i.e., the newly mixed dough's temperature, Ph, hydration, and ingredients present; dough temperature, more than any other factor, controls yeast and bacteria activity. Secondly, dough temperature is hard to change, and especially hard to change in a controlled way. Thirdly--and not an issue, but a reality--the home baker has more direct control over temperature than any other factor. (Ingredients is, of course, the second, but you can't turn a brioche into a ciabatta.)
Addressing the latter issue first, having recently built a proofing box, early experiences supported my concern that a dough's initial temperature would dominate the dough's average temperature for hours. Stated differently, the heat energy in a light bulb, or heating pad--typical heat sources in homemade proofing boxes--is low. Furthermore, the transfer of heat into a dough mass (a complex function of the dough's mass, surface area, temperature differences, and its specific heat) is slow.
This is not a bad thing. If the heat source is cranked up too high, undesired side-effects will likely occur; e.g., the dough's surface will dry out, yeast cells at or near the dough's surface will produce gas at a reduced rate. The solution to avoiding both these problems is straight forward: Set the DDT to the temperature desired for bulk fermentation. If your going to proof at 76°F (the most common temperature invoked by bread book formulae), 80*F (Tartine Bread). 82.5°F (Zojurishi bread machine pre-heat, and proof temperature most favorable to yeast growth and activity), or 90°F (best temperature favoring bacterial vs. yeast growth in most sourdough cultures.) adjust the mixes' water temperature to reach a DDT as close as possible to the intended bulk fermenting temperature. Conversely, 40°F if you're going to retard the dough in the refrigerator, and finish proofing at room temperture, or 55°F if your using a wine cooler--my preferred retarding temperature. Then your proofing box (or chiller) is maintaining the dough's initial temperature: a much less energetic job.
The first issue, also stated in a different way: why? What's the reason for a specific DDT? Flavor, Scheduling, or Texture? I can't think of a fourth reason, and texture is the most tenuous. Nonetheless, know why you've chosen a proofing temperature, and choose accordingly. And, if your writing a breadbook, fully explain why you chose a specificied initial dough temperature, including its benefits and downers.
David G
Comments
very informative and thought provoking.
Pam
I have been trying to warm up the proofing environment by setting the couche in front of a toaster oven set on warm. Based on my measurements even though the air temperature around the bread goes to around 78F it doesn't have the slightest impact on the dough temperature over the course of several hours. I have also found that even when I follow the formula for water temperature, frequently the dough comes out too cold. So I have been winging it and going hotter on the water temperature than recommended. This is an as yet unsolved problem for me. Have you been able to control dough temperature effectively with your proofing cabinet?
...but it doesn't come without planning. I work hard at getting the DDT within a degree or two of where I want to ferment the dough, and I pre-warm the proofing box before I put the dough mass into it. That's usually 20 to 30 minutes. Wood is a good insulator; conversely it holds heat well so the box does very well at maintaining a dough's temperature, but it takes quite a bit of heat energy to change the temperature of a kg or more of dough that's too warm or too cool. The proofing box I built struggles to change a dough's temperature. I routinely retard dough at 55°F in our wine closet also. It too struggles. I use ice-water to control DDT in those cases. In both warming and chilling doughs from mixing to pre-shaping I establish the dough temperature during mixing, and keep the fermenting dough either in the chiller or proofing box from the beginning of autolyse to loading into the oven except for those few minutes in the process when I'm manipulating the dough. I've recently tried warming previously chilled dough pre-shapes and final proof in the proofing box with good success, but so far its only one try. It one more area I'm focusing these days to learn more how to manage my baking.
There are a couple of very interesting threads here on TFL about DDT. When I first heard of it, about two years ago, I thought it was a very rough--and likely inaccurate--rule of thumb. I know enough about the thermodynamics of mixtures to have made that assessment. Dan DiMuzio, a professional baker, and author of a good textbook like baking book, bread baking: An Artisan's Perspective, used to contribute frequently, and very helpfully, to TFL. He "owned up" to the inaccuracies of baker's estimate of DDT, and referred to the "Friction Factor" as a "fudge factor".
Nontheless, I think its worth learning (as Dan does), and as you are doing, what works for you in your circumstances. I know that consistency in ingredients, and techniques, and practices--including controlling dough temperature--brings me consistent results: a goal of my bread baking since day one. In these nearly two years baking to reach my current level, I can claim I've nailed down only two or three bread formulae I feel I can make with routine and consistent success.
David G
David, It's interesting that you say that. I have been working on one formula and striving for exactly that - consistency. And haven't got there yet. When I get bored, I bake something else, but then go back to formula x and try, try again. I'll take a look at DiMuzio's posts. Thanks for pointing that out. It seems that there are many keys to good bread making, but this is way up there. -Varda