[Sca-cooks] Grinding Flour:Bran-Starch

[Terry Decker]

Extraction rate (IIRC) is about the percentage of the wheat grain that is 
actually converted to flour, not just starch, but also germ and a few other 
things.  As I recall, it's tested by burning a specified quantity of the flour 
and comparing the weight of the ash to the original weight.  Roller mills 
actually strip the germ from the wheat grains at the beginning of the process, 
leaving roller milled flour as mostly starch and protein.  I suspect that the 
difference in extraction rates may be attributed in large part to the germ, the 
oil containing portion of the wheat and how it affects the measurement of ash.

Modern bolting uses wire mesh screens.  Medieval bolting uses various weaves of 
cloth with the finest flour being bolted trough extremely fine weave silk.  
Medieval bolting takes longer and costs more, but it will produce extremely fine 
flour.  Farm baked bread was probably given a single pass through a horse hair 
sieve.

Medieval flour was whole meal.  Modern flour tends to have the germ stripped 
from it.  To make a flour similar to that which was used in period, one needs to 
produce an extremely fine whole meal flour, either take a whole wheat flour and 
sieve it very fine or find a source for whole wheat pastry flour.  If I am not 
worried about absolute accuracy, unbleached flour makes a fine substitute.  


The idea of mixing whole wheat and AP flour to make a substitute for medieval 
flour is a misunderstanding of the milling process.  I've already tried it and 
the results are unsatisfactory

I would also suggest that 80% extraction would have been from the best stone 
mills.  Depending on the quality of the stones and their dressing, the 
extraction rate might be considerably less.

Bear



________________________________
Bear wrote in 1998 (filed in the Florilegium):
"Stone ground wheat comes very close to the fineness of roller milling.  The 
chief difference is in the level of extraction.  Stone grinding reaches a 
maximum of about 80% extraction.  Roller milling goes above 90% extraction."

And this percentage is what the historicalfood site apparently uses. But Holly 
Stockley just posted:
"I've bolted hand-ground flour and come up with a product every bit as fine as 
commercial AP flour.  I suspect somebody mis-interpreted the data:  stoneground 
flour manages about an 80% extraction rate.  Modern roller mills do rather 
better.  This isn't a measure of how much bran is in the flour, but rather how 
much of the starch of the grain ends up in the flour portion.  Adding bran back 
doesn't match an extraction rate, but I can see where it could get confusing."

So, Bear, has your research in the intervening 12+ years modified to agree with 
what Holly is saying?  I don't see that you are both saying the same thing.  Is 
one correct and one incorrect?  Are both correct?

I sort of thought that using unbleached white flour was closer to what was 
available to the king's cooks than adding in some wholemeal flour.

(I think I'll roll over now and take a nap next to this lovely bone!)

Alys K.
-- Elise Fleming
alysk at ix.netcom.com
alyskatharine at gmail.com
http://www.flickr.com/photos/8311418@N08/sets/