I must be a bread nerd because this feels like a really good cliffhanger. I'm excited to find out what happens with a preferment and enjoying the suspense! Rest well. I hope tomorrow is more relaxing and as always, thank you.
Sorry this is really loooong!
There are three main factors to an open crumb:
- Hydration of 65% or greater
- dough strength (extensibility & elasticity)
- high protein (gluten) content.
Hydration: a minimum of 65% hydration is required to open up the crumb. A stiff dough (low hydration dough) slows yeast development and autolyse. Less CO2 and extensibility means a tighter crumb. Loaves with giant holes have about 80% hydration.
Extensibility is ability to stretch.
Elasticity is ability to spring back
There has to be the right balance between extensibility and elasticity.
- A dough that is weak (too much extensibility) can't hold its shape and cannot trap air bubbles very well. So it has a tighter crumb and little oven spring. A weak dough is caused by over-fermentation
- A dough that is too strong (too much elasticity), is difficult to shape as it springs back into a tight ball. It will bake up tough.
Other factors that effect an open crumb are enriched doughs and mixing method.
An enriched dough is any dough made with milk, butter, egg, AND/OR sugar. Fat and sugar inhibit gluten development as they are tenderizers. Gluten development is key to an open crumb as it provides the required dough strength both trap air bubbles, and expand with the air bubbles.
Mixing method: mixing everything all together, then kneading also inhibits an open crumb. The direct mixing doesn't allow the flour time to absorb the water. When flour is given time to hydrate, an enzymatic process called autolyse happens. This is the break down of of the protein (gluten) cells. The result is a more extensibility.dough. Have you notice when you mix water to flour, the dough is very stiff. Then you let the dough sit undistributed, and it becomes a lot softer. That's autolyse at work.
A preferment is a form of autolyse. There are four types:
- Poolish: 100% hydration (equal parts water and flour by weight). The amount of yeast depends on the fermentation time. Use less yeast if fermenting overnight (12 hr); more yeast if needed in 8 hrs. Given the high hydration and yeast, a poolish cannot ferment more than 16 hrs. An a 16 hr poolish would contain the tiniest pinch of salt. Poolish is used more for dough extensibility, but it does add flavor.
- Biga: 50% - 60% hydration of water to flour by weight. And has less yeast than a poolish. The lower hydration and yeast allows for longer fermentation. The long fermentation means more robust flavor. Biga is what gives ciabatta its flavor.
- Pâte fermentée: this is the use of day old dough in a fresh dough. The French invented the technique of reserving 1/3 of a fresh batch of dough to use in the levin for the following day's bake. The dough is taken after the bulk rise. So it's contains yeast and is developed dough. I've never used one, so I can't tell you how well they work.
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A preferment is usually 25% to 50% of the final dough.
For a crusty bread, use 50%. For a loaf baked in a pan use less.
A poolish must be made by weight since all ingredients weigh differently. For example, a cup of water is 8 ounces, but a cup of flour only weighs 4.25 to 5 ounces.
Mix an equal amount of water by weight and 1/8 tsp - 1/2 tsp of active dry yeast. Let sit to dissolve. It's not a sponge, so you don't have to let it bubble up. You just dissolve it in water for better distribution give the tiny amount.
Mix the yeast water into the flour until all the flour is moistened. You aren't developing gluten so just mix until all the flour is moistened. Loosely cover with plastic wrap and place in a draft free place. I place my in my oven.
Let it ferment overnight (I use a 12 hr poolish). If you want to use it in 8 hrs, increase the yeast. If you want to ferment 16 hrs, use a tiny pinch of yeast. Below is a table for times and yeast amounts.
If you use too much yeast, it will eat through its food supply and start to die off.
Example of adapting a recipe for a poolish. Say a loaf of bread is made with
500g flour
300g milk
2 teaspoon yeast
You decide to convert 35% of the dough to a poolish.
Calculate 35% on the total weight of the flour.
Flour: 500 x .35 = 175
Use 175g flour in the poolish. Reserve the remaining 325g flour for the final dough.
Since the weight of the flour needed is 175g, subtract that amount from the total milk
Milk: 300 - 175 = 125
Use 175g milk in poolish, reserve 125g milk for the final dough
Yeast is a bit tricky. You only need a tiny amount for a poolish given the hours of fermentation. Since it's easier to make the poolish the night before. I like to use a 12 hr poolish
Yeast: 1/2 tsp. See table on yeast below
So it would look like this
Poolish
175g flour
175g milk
1/2 teaspoon active dry yeast (see table below)
Final dough: remainder of ingredients
325g flour
125g milk
1 1/2 teaspoon active dry yeast
salt & any other ingredients
Made the final dough and add the poolish.
Mix the remaining flour, yeast, and liquid to just moisten. Cover and let rest 30 minutes. Add the salt and any other ingredients to the final dough. Then add the poolish to the dough. Knead and rise per recipe instructions.
A high hydration dough cannot be kneaded. Various techniques are used in place of kneading. I find the stretch and fold technique during the bulk fermentation the easiest and most straight forward. With stretch and fold, fewer air bubbles are popped, so there's a lot more holes. After bringing my dough together, I let it sit about 50 mins before I start stretch and fold. Google stretch and fold--there's a ton of videos online.
Creating big holes in bread involves a lot of factors and practice. I think many bakers have gone off the deep in regards to the open crumb. They think more and bigger is better. There's nothing to bite and chew.
NOTE on milk: Milk is used for flavor and dough strength. Milk protein aids gluten development. I've never made a poolish with milk, so I don't know if it will work. I've used a combination of water and evaporated milk. Evaporated milk is concentrated, so it has twice the protein of whole milk. I replace 10% of the water with evaporated milk. But you can try milk and see if it works.
Yeast weights and amounts
- 1 packet dry active yeast 7g = 2 1/4 tsp
- 1 tsp active dry yeast = 3g
- 3/4 tsp active dry yeast = 2.25g
- 1/2 tsp active dry yeast = 1.5g
- 1/4 tsp active dry yeast = 0.75g
- 1/8 tsp active dry yeast = 0.375g
Amount of yeast to use depends of fermentation time:
- Poolish up to 8 hours in advance: .02 - .03
- Poolish up to 12 hours in advance: .01 - 0.2
- Poolish up to 16 hours in advance: .005 - .01
In the example, the 12 hr poolish was made with 175g flour.
175 x .01 = 1.75g. So that's roughly 1/2 teaspoon of yeast.
I actually use a lot less than the standards. I use 1/8 tsp for up to 200g flour.