A proofing cabinet should only be necessary if you need to ferment the
dough quickly. The yeast activity does decrease in proportion to the
ambient temperature but that is not a disadvantage. The greater time will
give the other critters (Acetobacter and lactobacillus) time to work their
magic as well as the enzymes in the dough to work. This will result in a
more intense flavor and improved crumb. The velocity of the yeast activity
changes by a factor of two for each 17 degrees F. (9.4 C. if my math is
correct) This means that the activity at 60 degrees F. will be half as fast
as it would be at 77 degrees F. and twice as fast as at 53 degrees F.
If there is a need to adjust the velocity of the fermentation it may be
better to use the refrigerator rather than a proofing cabinet. This
process, called retardation, gives time for the yeast to work and the
ability to fit the process in your schedule. It generally takes dough about
one hour to come to room temperature after retardation. It can then be
rounded, fermented, and baked.
An inexpensive way to experiment, if you need to do so, is to place an
electric heating in a cardboard box. Set it on a low setting and set a
grate of some sort to keep the bowl above, but not in direct contact with,
the pad. Stab a metal stem thermometer through the box to monitor the
temperature. A box can be flattened and stored easily.
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