Thursday, November 1, 2007

How to calculate the friction factor for your mixer


For more info on how to obtain the desired dough temperature, please click here.
To calculate your mixer's friction factor (i.e. the amount by which mixing increases the dough temperature, an important value to take into consideration when figuring out what water temperature to use), the easiest way, according to Jeff, is as follows:
  1. Write down the temperatures of the air, the water (using water at between 65 and 75 F) and the flour prior to mixing a straight dough (that is, without preferments. If using a preferment such as a poolish, you'll need to record its temperature as well)
  2. Mix dough as usual
  3. Take the dough temperature
  4. If the dough temperature is for instance 76F, then multiply 76 by 3 (since we already know the temperatures of three of the elements to take into consideration), in this case: 228 (if using a preferment, multiply by 76 x 4)
  5. Then substract the air, flour and water temperatures (as well as the preferment temperature if using)
  6. What's left is the temperature increase resulting from the friction, in other words the value of the friction factor for your mixer.
It is good to remember that:
  • The more dough there is in the bowl of the mixer, the lower the friction factor
  • Wetter doughs (for instance ciabatta dough) generate less friction than dry doughs (such as challah dough), so for ciabatta up the water temperature by 5 F (do the opposite for challah).





3 comments:

  1. Method of calculation is inaccurate because it does not take into consideration the weight of each component.

    You will need to figure out the percentage of each component relative to total weight of all components combined, then multiply percentages by corresponding temperature of each component and add them up. The result is the temp of all components combined before mixing. You then subtract the result from temperature of dough after mixing. Done, you got the friction factor.

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