Rose says using the correct flour is important. She mentions King Arthur brand most often, so I bought a fifty pound sack of Sir Lancelot hi-gluten flour, protein content ? 14.2%. And since I am tired of paying such a high price for a very small box of cake flour I tried to find Queen Guinevere Hi-Ratio Cake Flour, (http://www.kingarthurflour.com/professional/Conventional-bakery-flours.html ).
But I had to settle for a fifty pound sack of General Mills ? Gold Medal Purasnow Cake Flour, protein content ? 8% because no one stocks Queen Guinevere in Kansas City.
I decided I would make my own 9.2 % protein pastry flour by calculating the exact two proportions to combine. Perhaps you will profit from my experience. I have a formula here that you can use to start with any two flours and end up with any percentage of protein desired.
Since protein percentages are specified in parts per hundred, it is convenient to start off with 100 grams of Cake Flour so we can think of one percent and one gram as the same amount.
Goal: Mixture with 9.2% Protein
Using: Hard flour, 14.2% Protein
and Weak flour, 8% Protein
So we want to increase the protein from 8% to 9.2% by combining these two flours.
If we add 25 grams of Hard Flour, it works. Here is the math. (For your own percentages, you will have to jiggle the numbers until you get to your desired protein level. Or you can use an exact Algebra formula I will show you. Believe me, jiggling the numbers is easier than algebra).
Add 25 grams of Hard Flour: 3.55 grams of protein, (14.2 multiplied by 25% = 3.55)
Hard Flour Protein: 3.55
Cake Flour Protein: + 8
Total grams of Protein: 11.55
Now remember, the total weight of the mixture is 100g + 25g = 125 grams
So, 125 divided by 11.55 = .0924 Close enough!
Let?s say your recipe calls for 200 grams of flour, how can it be figured?
Since the 9.24 Protein goal is obtained when:
100 grams cake flour is added to
25 grams hard flour
125 grams Total weight
The percentage of the additional amount is 20% of the total.
25 grams divided by 125 grams = 20%
Therefore the amount of hard flour is 20% of 200 = 40 grams of hard flour And the weak cake flour amount is 80% or 160 grams!
*And now for the Algebra Equation:
(8+(14.2X)) Divided by (100+(100x))
Solve for X, The answer is .25
But remember this is the proportion of additional hard flour for 100 grams, just the first step. After this, you must figure how many grams of flour your recipe calls for as I have explained above.
You may plug in your own percentages in this formula and check out your answer with Microsoft?s Free Algebra Calculator which you may install from http://www.microsoft.com/en-us/download/details.aspx?id=15702