Apr 28, 2020

Bread Flour

Ingredients

  • 100% all purpose flour
  • 2.6% vital wheat gluten

Process

Whisk vital wheat gluten into all purpose flour. Use in recipes that call for bread flour.

Notes

The Short Version

Rather than keeping bread flour on hand, I have recently taken to simply mixing my own from all purpose flour and vital wheat gluten. It is relatively well known that this is possible, but searching around on the Internet for exactly what ratio to use turns up a wide variety of results, most of which contradict each other and some of which contradict themselves. The general consensus seems to be that between 1 and 3 tablespoons of vital wheat gluten should be added to between 1 and 2 cups of all purpose flour. That’s a little wishy-washy for me, so after some experimentation I have started using this ratio.

The Long Version

If I sound critical of various food blog posts making luminous and differing recommendations, it’s because I’m being unfair. In fact, what is actually wishy-washy is the concept of all purpose flour itself—namely, how much gluten it contains in the first place.

I am currently using King Arthur’s Sir Galahad flour, which is described on the King Arthur professional flours product page as having 11.7% protein and an ash content of 0.50%. I’ve seen various claims online that this same flour is rebranded as the “King Arthur Unbleached All-Purpose Flour” that can be found in most grocery stores. Considering King Aurthor AP flour is also advertised as having an 11.7% protein content, and based upon side by side comparison, I have no reason to question these claims.

If all AP flours had a protein content of 11.7%, there would be no reason why a ratio like the one I’ve listed above wouldn’t simply be thrown around universally. Unfortunately, that is not the case. Currently, the Wikipedia article on flour’s “all-purpose flour” subsection cites two different sources, which disagree with one another, concerning the protein content of AP flour. If both of these sources are to be believed (and they seem credible to me), protein content in AP flour can range from around 9.5% to 12%.

Okay, but what about bread flour? Is there a hard and fast protein percentage associated with bread flour?

Not really. The “Bread flour” subsection of the article mentioned above also cites two sources, which also disagree, and also indicate a relatively broad range of protein contents—11.5% to 14%. Interestingly, at 11.7% protein, King Arthur All-Purpose Flour could be considered, by some standards, to be a bread flour! The flour King Arthur does market as “bread flour” for consumers, and as “Special Patent” for professionals, has a protein content of 12.7%, which is what I’ve aimed for capturing in the ratio above.

But how did I land on that number? Well, above I mentioned “some experimentation,” but this is a bit of a fib since most of my experiments have involved adding around the same amount of vital wheat gluten and enjoying the final product. In order to actually arrive at this amount in the first place, I did some math.

The Math

If you’ve searched around on the internet about this as much as I have, you’ve inevitably come upon posts that offer equations for calculating how much vital wheat gluten should be added to all-purpose flour (or cake flour) in order to raise its gluten content. For examples of these posts, see this StackExchange answer, this blog post on The Fresh Loaf, and/or this blog post on The Kitchen Whisperer. The general idea behind these equations is that the gluten content of a final flour mixture is a function of the gluten content of the initial flour and the gluten content of the vital wheat gluten.

We can model this with the following system of equations, where x represents the proportion of flour that should be used and y represents the proportion of vital wheat gluten that should be used.

target_gluten_percent = flour_gluten_percent * x +
                        vitalw_gluten_percent * y
1 = x + y

We know the sum of x and y must be 1, since they describe the ratio of two ingredients in a mixture. We can therefore simplify into a single equation.

y = (target_gluten_percent - flour_gluten_percent) /
    (vitalw_gluten_percent - flour_gluten_percent)

If we want the percentage of flour we need, we can simply take 1 - y and if we want the percentage of vital wheat gluten we need as a baker’s percentage we can simply divide y by that number.

Working backward, since I’m using a baker’s percentage of 2.6% vital wheat gluten, that means I’m actually using 1 - (1 / 1.026) = 2.53% vital wheat gluten. Since I know my flour protein percentage is 11.7% and my vital wheat gluten protein percentage is 71%, solving for target_gluten_percent indicates that protein content of my final mixture is around 13.2%. Not bad.

Final Thoughts

Since most recipes using baker’s percents call for “100% flour,” it probably makes sense to think of the ratio of flour to vital wheat gluten in terms of percent of final mixture (i.e. the final flour mixture should be comprised of 97.47% AP flour and 2.53% vital wheat gluten). It also probably makes sense to calculate these coefficients for your flour and vital wheat gluten if you’re actually looking for a consistent product.

And if not? With the ratio I listed at the beginning of this post, assuming vital wheat gluten ranges from around 65% to 85% protein and that the range of AP flour percentages mentioned on Wikipedia is reliable, you’ll end up with a final product somewhere between 10.7% and 13.7% protein.

So, in conclusion, if you’re feeling just ambitious enough to weigh out all your ingredients on a scale but just lazy enough to not want to check the gluten contents of your flour and vital wheat gluten then plug them into the equation above, 2.6g of vital wheat gluten for every 100g of AP flour isn’t a the worst option.

Will it always be perfect? What is perfect, anyway?

Will it always be better than what you started with? I’d be willing to bet.