March 27, 2011 - 5:35pm
Rule of 320?
On the Sourdough Home website it states:
The last wrinkle is that when you are using sourdough or other preferments the rule of 240 becomes the rule of 320. Take the temperature of the sourdough or other preferment as well as the temperature of the flour, water and room. Subract all from 320, rather than 240. If you are using Celsius, this becomes the rule of 100.
http://www.sourdoughhome.com/bakingintro2.html
Has anyone heard of this? Any insight? A google search has turned up nothing so far. It seems to me he has included too many parameters.
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Desired Dough Temperature(search)
Seems to me, it's just a rough guide; a short cut, to get you there. Should be pretty easy to check(not that I don't take Mr. Avery's word for it).
More on DDT(lots more with web searches):
http://www.kingarthurflour.com/professional/dough-temperatures.html
"...The calculation of Desired Dough Temperature involves taking into consideration three or four factors (occasionally but rarely more than this). These factors are the variables over which we have no control when we enter the bakeshop and prepare to mix the dough: the air temperature, the temperature of the flour, the "friction factor" of our mixer, and the temperature of the preferment, if any. After figuring these, we can simply and quickly establish the correct water temperature (the only variable over which we have control). At the end of this discussion we will talk about friction factor in more detail..."
There is a similar formula in Hamelman's "Bread" Pg. 383. DDT "desired dough temperature" which is a formula that a baker would use to temp all his ingredients, air temp and friction factor of the mixer, to arrive at a certain dough temp. With water being the variable. So you raise or lower the water temp to arrive at the DDT. This is what pros and advanced bakers use so the doughs in the production line hit the oven at the proper time. Hamelman uses 228 and 304 degrees F as a Total Temp Factor within the formula. The difference being 228 = straight dough and 304 for added preferments. I tried to keep it simple, hope you understand.
Jim
I was familiar with the rule of 240; it was the rule of 320 for preferments that was new to me.
Larry