Thursday, November 22, 2012

Dough hydration for beginning bakers

It seems like I respond to these questions too often on TFL.

Lots of beginning bakers (especially those fooling around with sourdough or natural levains) often start with recipes that give sourdough amounts by volume. For example:

To feed your starter, take 1/4c of starter and feed it 1c flour and 1c water.

The issue that I have with this is that using this starter (a very liquid starter) is this: while easy to remember the proportions for feeding, it's much harder to tell when the sourdough starter is fully ripe and ready to use.

Just so we're clear: feeding 1c flour and 1c water does not make a 100% hydration starter. Starter hydration percentage always represents the ratio of flour to water by weight, not volume.

  • 1c of white flour weighs typically around 125g, but can weigh 120-140g, depending on how you measure. 
  • 1c of water weighs around 236g

This means that a starter fed equal volumes will result in a ~188% hydration starter! (236g water/125g flour)

So what's the problem with this? Here's a very common sourdough recipe that I was investigating:

1 cup active starter (fed using 1c flour and 1c water)
3.5 cups flour
1 cup water
1 tsp salt

Let's translate this common recipe to a weight-based formula:

1/2c flour + 1/2c water = 62.5g + 118g = 180.5g
3.5c flour @ 125g/cup = 437.5g
1c water = 236g
1 tsp salt = 7g

So how does this help? What does this tell us?

First, let's total the flour in the recipe (62.5 + 437.5 = 500g) and water (118+236 = 354g)
354 / 500 = .708, or 70.8% hydration, which is slightly on the high side for a sourdough bread, which tends to get wetter and floppier the longer it ages.

Second, we are using 180.5 / 437.5 = 41% of the final flour in the recipe in starter, which is somewhat high, especially with a liquid starter...this means it will probably ferment really fast, perhaps more quickly than desired for a sourdough, which like all doughs, will develop deeper flavor during longer fermentations.

BTW, if you want to calculate dough hydration easily, Joshua Cronemeyer's online calculator is one of the easiest.

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