Itís been a while since I last read anything by Tom Lehmann about how to supplement a particular flour with a particular protein content with vital wheat gluten to achieve a final flour with a desired, higher protein content. I also wondered whether he would use the information that I provided to him (via email) after November created the Mixed Mass Percentage Calculator at http://foodsim.unclesalmon.com/,
and for which I provided the link to Tom.
Apparently, Tom continues to use the 0.6 rule that he has advocated all along, as noted by a recent post at the PMQ Think Tank at http://thinktank.pmq.com/viewtopic.php?p=23630#23630.
For convenience, I have copied and pasted below the pertinent part of that post that applies to the determination of vital wheat gluten amounts:For every 1% vital wheat gluten that you add to your flour, you will increase the overall protein content by roughly 0.6%, so, lets say that you have 22.5 Kg of flour at 11% protein content, and you add 1% (225 grams) of vital wheat gluten to the flour, the protein content is now at 11.6%. If you want to increase the protein content to say, 13% you would need to add 3.3% (743 grams) of vital wheat gluten to the flour.
I ran Tomís numbers for the two examples noted above through Novemberís tool, using the Gilco brand of vital wheat gluten, which is a commercial product sold to professional bakers, and got 210.9 grams of vital wheat gluten for the 11.6% example, and 703.1 grams of the vital wheat gluten for the 13% example. Had I used the Bobís Red Mill brand of vital wheat gluten I would have gotten the same results because its protein percent (75%) is the same as the Gilco brand. Using either the Arrowhead Mills or Hodgsonís brand of vital wheat gluten, I would have gotten numbers higher than Tomís because of the lower protein percent (65% and 66.6%, respectively) of those two brands. As noted previously, Tom has stated that the 0.6 rule is just a rule and whether one uses the 0.6 rule or a more accurate one, the results will be close enough.
I believe Tom also forgot to mention in his post that the amount of the base flour, 22.5 Kg in this case, should be reduced by an amount equal to the calculated vital wheat gluten quantity so that the total weight remains the same. However, he did mention that one should add more water to compensate for the addition of the vital wheat gluten.