If you're serious about baking your sourdough bread, you likely came across the term sourdough hydration. There's talk about low hydration and high hydration sourdough recipes. And lots of recipes call for a 100% hydration sourdough starter. You'll be perfectly fine with not knowing what that is and successfully bake your sourdough bread. But if you want to take sourdough baking to the next level, you have to know and, most importantly, understand what sourdough hydration stands for.
In this article, we will go over the following:
- What is Hydration in Sourdough Baking?
- Where Does the Term Come From?
- How to Calculate Hydration?
- Why is Understanding Hydration Important?
- Understanding the Hydration of a Sourdough Starter
- How does Hydration Affect the Handling of the Dough?
- How Does Hydration Affect the Bread?
- How do Different Types of Flour Affect Hydration?
- Examples of Low and High Hydration Bread
- What is the Best Hydration for Your Sourdough Bread?
- Takeaway Message
What is Hydration in Sourdough Baking?
The dough hydration basically means the amount of water in the dough, relative to the flour used. It tells us how much water there is in relation to the flour. First, we look at how many grams of flour a certain recipe calls for. Then we look at how many grams of water it requires. Combining both, we end up with a percentage. And based on that percentage, we can predict how to best handle the dough and what the finished result will look and taste like. So for example, if we use 100g of flour and 70g of water in a recipe, the recipe results in bread with 70% hydration.
Where Does the Term Come From?
The term is actually tightly tied to what's called "the baker's percentage". The baker's percentage tells us the amount of any given ingredient relative to the amount of flour in a recipe. So If we use 10 grams of salt for bread that consists of 500 grams of flour, that means 2% is the baker's percentage of salt used in that recipe. Hydration is nothing more than a baker's percentage of water in a recipe.
Some sources still claim that hydration is the ratio of water in the dough, which is not correct! Another common misconception is that we can calculate baker's percentage with measuring cups, which is also false: we have to measure in grams to come to the right baker's percentage.
How to Calculate Hydration?
Using the explanation above, it is not hard to figure out how to calculate the hydration:
Water (in grams) / flour in grams, x 100 = hydration percentage
Why is Understanding Hydration Important?
Because water and flour are the main ingredients in bread (and many baked goods), their ratio plays a major role in what the dough is going to be like and what characteristics the final product will have. Almost every aspect of the bread-baking process can be optimized using the level of hydration. Below, we will go over some obvious ones.
Understanding the Hydration of a Sourdough Starter
Just like bread dough, the sourdough starter has a hydration percentage too. The most common sourdough starter percentage is 100%. This type of starter gets fed an equal amount of water and flour at every feed, which makes it a 100% hydration starter.
Why is the 100% hydration starter the norm, you may ask? Because a starter at that hydration percentage is easy to pour, easy to mix in with the water and flour, and easy to keep happy and healthy. In addition, if you use a 100% hydration starter in your recipe, you can leave it out of the hydration equation.
Because the ratio of flour and water in a starter like that is 1:1, you can simply skip it altogether, because it does not change anything. But if your starter is, let's say, 80% hydration, you will have to include that in your hydration calculation. That means that you have to add the amount of flour and water your starter consists of to the total water and total flour amount. Then you have to run the hydration formula from above and get a hydration level of the dough.
I personally like to keep my starter at a little lower hydration level than 100%. I don't measure, but I guess it's between 80% and 90%. It's not a stiff starter, but it is not "standard" either. That way, it goes through a feed a bit slower and I don't deal with so much discard. I make sure it is runny enough that I can still pour it and mix it with water in recipes easily.
How does Hydration Affect the Handling of the Dough?
In most simple terms:
- high hydration dough will be sticky and runny
- low hydration dough will be stiff and quite rigid
Those are extremes of course. But here are the most important consequences of hydration level and what they mean in practice of handling the dough:
Higher hydration dough (wetter dough) will be easier to mix together. You'll have an easier time mixing in additions as well (ex. raisins, shredded cheese, chocolate chips). On the flip side, you'll most likely have to mix it by hand because it will never form a ball in a stand mixer.
Lower hydration dough (stiffer dough) will be difficult to bring together. It'll be more challenging to mix in other ingredients as well. You'll really benefit from using a stand mixer with lower hydration doughs because kneading it by hand will be hard and time-consuming.
Higher hydration dough (wetter dough) will develop gluten bonds much slower than lower hydration dough, so it will require more kneading to get there. You'll even have to turn to coil fold instead of stretch and fold method because the dough will be too wet for the latter. Coil folds require you to lift the dough in the middle, leave the sides to stretch all the way down, and repeat across the other side.
Lower hydration dough (stiffer dough) will have faster gluten development and may not need a lot of kneading after it is incorporated.
Higher hydration dough (wetter dough) will be difficult to shape because it is a wet dough and will stick to everything: your work surface, your fingers, etc. For easier management of this kind of dough, you can flour your counter and handle the dough with wet hands to prevent sticking. You can also put the dough in the fridge for a few hours after bulk fermentation at room temperature and before shaping. Be sure to take a piece of parchment paper and put it under the bread, dough before baking. But mainly just lower your expectation of the final shape when going for a high hydration dough. For example, you'll never succeed in making high hydration bagels.
Lower hydration dough (stiffer dough) will be really easy to shape. It will also hold the shape really well, so you'll be able to manipulate it more (and make sourdough babka, for example!)
Higher hydration dough (wetter dough) will ferment faster and need less rising time. That is because, in high hydration dough, the years and bacteria from the starter go through "food" (flour) quicker. Take that into account when you calculate the fermentation time.
Lower hydration dough (stiffer dough) will ferment slower and will need some extra time to rise, but it will hold the shape better.
Read more about how long should your dough ferment at room temperature.
How Does Hydration Affect the Bread?
We often know what we want our bread to look and taste like in the end, but are stuck not knowing what specific thing we need to tweak to get there. Hydration is one of the major factors. We can change the final result by tweaking the dough's hydration. In general, higher hydration breads are softer, and have a more open crumb and crispier crusts. So why not bake only with high hydration? Because they are also more difficult to bake and some breads are literally impossible to bake with high hydration. Think cinnamon rolls for example. For those, you need to be able to roll out the dough and get it shaped into rolls. With a very high hydration dough, that would simply not be possible. Low hydration doughs also get a better oven spring.
Texture and Crumb
A high hydration sourdough bread will have a more open crumb, which means bigger holes. It will also be softer and more springy. Whereas a lower hydration level will yield a more chewy bread with very even little holes.
A crust of a bread with higher hydration level will be thinner, crispier, and will stay crisp for longer. Lower hydration bread will have a thicker and harder crust.
Among other factors, different hydration levels affect the taste of the bread as well. Although taste is a very subjective metric, many people describe the high hydration bread as more complex in flavor and only mildly sour. Low hydration bread tastes more sour and the flavor is less developed.
How do Different Types of Flour Affect Hydration?
Another thing to consider when playing with different hydration levels is the type of flour you are using. As a rule of thumb: the more processed the flour is, the less water it absorbs. That means if you are baking with white flour (including all purpose flour and bread flour), you'll make a higher hydration bread more easily. If you decide to tweak a recipe with white flour and use whole wheat flour instead of white, you'll need to adjust the hydration accordingly. in this particular case, you'll need to add more water. Whole grains are more absorbent, so you'll end up with a dry dough if you don't provide them with more water. Even the same types of flour across different brands can vary in absorbency!
Examples of Low and High Hydration Bread
Just so you'll get a rough idea of what high or low hydration means in practice, here are some examples.
Low hydration bread: bagels, pretzels, bread sticks, and the majority of sweet and enriched bread (like babka).
What is the Best Hydration for Your Sourdough Bread?
If you've come this far, you probably understand that hydration is much more than a number. Therefore, as with anything sourdough, we have to trust our feeling a little. Because bread with whole grain flour with 70% hydration will be very different from white bread with 70% hydration. Furthermore, a dough with 70% hydration in Mexico City will behave differently than a dough with 70% hydration in Paris. That is because elevation and humidity also affect hydration. But there are some clues as to what is your optimal hydration level based on what you want from your bread.
The majority of sourdough recipes (that I came across) use a hydration level of around 70%. That is a great starting point if you are used to some sourdough baking and can handle a dough that is a bit sticky and harder to shape.
If you are a beginner, I suggest you start with lower hydration at first. Learn how to handle the dough and get the hang of it, then gradually increase your hydration by 1 - 2% at a time.
If you want to bake an enriched dough or a dough that needs to be a certain shape in the end (or both!), start experimenting with lower hydration at first. See how much water the dough can handle while still holding the shape you want it to. You will soon find a sweet spot.
If you live in a hot and humid climate, add a little less water than the recipe calls for. On the flip side, if you live in a cold, dry climate, add a bit more.
As a rule of thumb, always start with a little lower hydration level and see how much you can handle. There'll be a lot of trial and error. It helps to write down what combinations worked best for a certain recipe, so you'll know exactly what to do next time. Soon, you'll nail all your recipes down, and then some! Keep in mind that even when you hit just the right ratio in the middle of summer, you will likely have to tweak it a bit to work best for the wintertime.
But as always, don't forget to have fun figuring it all out!