Baker’s Percentage Tutorial, Part 4

May 12 2008 at 12:00 am

This final installment in the Baker’s Percentage tutorial series concerns breads that are made with preferments. (A preferment is a poolish, biga, sponge, sourdough starter, etc., where a portion of the flour is fermented prior to the mixing of the final dough.) If you missed the first three parts, you’ll want to read them before diving into this one. An index of the entire tutorial is here.

A preferment can be thought of in different ways. On one hand, it is a dough unto itself, and it has a BP formula all its own. But a preferment is also an ingredient in the final dough.

Look at this formula for baguette dough made with a poolish. The blue table shows the formula for the final dough, scaled to make 2340 g of dough. The yellow table shows the formula for the poolish, scaled to make 936 g, the amount needed for the final dough. Note that the formula for each part is based on the amount of flour needed for that part. Also note that the poolish is listed as an ingredient in the final dough formula.

Ingredient	%	Grams	%	Grams
	Poolish		Final Dough
Flour	100%	468 g	100%	900 g
Water	100%	468 g	52%	468 g
Instant Yeast	0.06%	0.3 g	1%	9 g
Salt	–	–	3%	27 g
Poolish	–	–	104%	936 g
Total	200%	936 g	260%	2340 g

The formula for the final dough might seem at first to be a bit unbalanced. 52% hydration — is this a very stiff dough? (Remember hydration is percentage of water, and 52% is more appropriate to a bagel than a baguette.) 3% salt — is that way too much? (2% is usually about right.)

Ah, but — remember that poolish! It’s an ingredient in the final dough just as the water, yeast, and salt are. But it’s no ordinary ingredient, because it brings 468 g of flour and 468 g of water to the overall composition of the dough. If we factor in those contributions, things make a lot more sense.

When a dough has preferments, it’s helpful to look at the total formula (sometimes referred to as overall formula). The total formula gives the total amounts of all the “raw” ingredients, including those contributed by the preferment(s). In a total formula, the preferments are not listed as ingredients themselves, but their component ingredients are factored in.

For the baguette dough, we look at each ingredient and add together the number of grams contributed by the poolish and the grams contributed in the final dough to yield the total weight of each ingredient in the overall dough composition. This is the green “Grams” column. The green “%” column is then calculated by converting these amounts to a BP formula (see Part 1 if you forgot how to do this).

Ingredient	%	Grams	%	Grams	%	Grams
	Total Formula		Poolish		Final Dough
Flour	100%	1368 g	100%	468 g	100%	900 g
Water	68%	936 g	100%	468 g	52%	468 g
Instant Yeast	0.68%	9.3 g	0.06%	0.3 g	1%	9 g
Salt	2%	27 g	–	–	3%	27 g
Poolish	–	–	–	–	104%	936 g
Total	171%	2340 g	200%	936 g	260%	2340 g

I find total formulas useful because they help you quickly assess the overall dough makeup (see Part 2). However, the final dough and preferment formulas are more useful when you’re actually mixing or want to scale the dough. (Surprisingly, many books that go to the effort to explain BP give either total or final dough percentages. The only book in my library to give both is Rose Levy Beranbaum’s The Bread Bible. Rose, you have my undying appreciation and admiration!)

Now let’s analyze the formula for a bread in which the preferment is an 80%-hydration sourdough starter. The final dough formula (scaled here to make 1110 grams of dough) is:

Ingredient	%	Grams
	Final Dough
White flour	80%	400 g
Rye flour	20%	100 g
Water	66%	330 g
Salt	2%	10 g
80%-hydration sourdough starter	54%	270 g
Total	222%	1110 g

The recipe doesn’t specifically say how much flour and water are in the starter, but we can figure that out by expressing the starter as its own formula. A starter is just flour and water, so an 80%-hydration starter has this BP formula as shown in yellow:

Ingredient	%	%	Grams
	Starter	Final Dough
White flour	100%	80%	400 g
Rye flour	–	20%	100 g
Water	80%	66%	330 g
Salt	–	2%	10 g
80%-hydration sourdough starter	–	54%	270 g
Total	180%	222%	1110 g

In Part 3 we saw how to make a given amount of dough from a BP formula. Applying that here with the needed 270 g of starter, we can calculate the grams of flour and water in the starter:

Ingredient	%	Grams	%	Grams
	Starter		Final Dough
White flour	100%	150 g	80%	400 g
Rye flour	–	–	20%	100 g
Water	80%	120 g	66%	330 g
Salt	–	–	2%	10 g
80%-hydration sourdough starter	–	–	54%	270 g
Total	180%	270 g	222%	1110 g

So the 270 g of starter contributes 150 g of (white) flour and 120 g of water to the final dough. Now we can calculate the total formula as we did with the baguette dough above, and we can see that this is a 69%-hydration dough whose overall flour content is 85% white flour and 15% rye:

Ingredient	%	Grams	%	Grams	%	Grams
	Total Formula		Starter		Final Dough
White flour	85%	550 g	100%	150 g	80%	400 g
Rye flour	15%	100 g	–	–	20%	100 g
Water	69%	450g	80%	120 g	66%	330 g
Salt	1.5%	10 g	–	–	2%	10 g
80%-hydration sourdough starter	–	–	–	–	54%	270 g
Total	170.5%	1110 g	180%	270 g	222%	1110 g