One of the hardest numbers to get out of millers is the rated absorption values for their flours. For example, General Mills does not quote rated absorption values for their flours. King Arthur is one of the few that does for its professional flours, as you can see at http://www.kingarthurflour.com/professional/specifications-conventional-bakery-flour.html,
but not at the retail level. A few years ago, I called King Arthur to try to get the absorption values for the King Arthur all-purpose flour and the King Arthur bread flour, as I noted at http://www.pizzamaking.com/forum/index.php/topic,4646.msg39204/topicseen.html#msg39204
. On several occasions in discussions with other millers beyond the two mentioned I asked for such values and was either told that they didn't know or would have to check and get back to me.
I also take into account the fact that the "operational absorption rate" can be a few percent higher than the rated absorption value. That aspect is discussed in the last paragraph of the abovereferenced post. In the above example with the Superlative flour, I was treating the 62.55% value as the operational value and the 60.55% value as the "rated" absorption value. In November's PM to me, the values of Ph
that he gave me represented the hydration a given flour can "withstand" in the absence of knowing what the rated absorption value of the flour is. If November's equation can get me into the ballpark when I don't know the rated absorption value of a given flour but have the input values to the equation, that will make me happy.
In another example that November gave me, he cited a Ph
value for the KASL flour of 65.43%. He used a Pf
value of 2.4 for that flour, which is not the exact value, and he did not consider the effect of the moisture content of the flour in his calculation. The correct value of Pf
for the KASL flour is 2.81% (see http://www.kingarthurflour.com/professional/nutritional-analysis-bakery-flour.html
). Re-doing the calculation, I get a value for Ph
for the KASL flour of 65.36%. As I understand what November was telling me, that would be the operational value, and the "rated" absorption value would be 2% less, or 63.36%. Using the GM specs for the All Trumps high-gluten flour at http://www.gmflour.com/gmflour/Flour_SpecSheet/ALL%20TRUMPS%20BL%20BR%20ENR%20MT.pdf
, I get a value for Ph
of 65.42% for the All Trumps flour. Subtracting 2% from that number, I get a "rated" operational value of 63.42%. I don't recall where I got the 63% number for the All Trumps flour but it was not from GM.
There must be a good reason for millers not wanting to unilaterally and willingly cite rated absorption values. As you know, there are all kinds of things that can affect how a given flour is hydrated. I tried to address many of these factors in the post at Reply 3 at http://www.pizzamaking.com/forum/index.php/topic,12211.msg115225.html#msg115225.
I might add that when I talked to the flour expert at Pendleton Mills about the Power flour, he made a point to emphasize that the rated absorption value given in their specs was in relation to a moisture content of the flour of 14%. However, that value can change once the flour leaves the mill, enters the distribution channel, and ends up being stored somewhere until delivered to the end user. You will note from Reply 125 at http://www.pizzamaking.com/forum/index.php/topic,14928.msg151643/topicseen.html#msg151643
that I queried the Pendleton flour expert on the 65% rated absorption value for the Power flour, especially when viewed against other flours with higher protein levels. According to him, it is the type of grain used to make the Power flour and where it is grown.
EDIT (4/15/14): For the most recent link to the GM All Trumps flour, see http://professionalbakingsolutions.com/product/all-trumps-enriched-flour-50-lb/50111000
EDIT (9/26/14): For the Wayback Machine version of the KA spec sheet, see http://web.archive.org/web/20121104053110/http://www.kingarthurflour.com/professional/specifications-conventional-bakery-flour.html