The hydration of your dough is the amount of flour compared to the amount of water in your starter. We recommend maintaining a 100% starter, which means the amount of flour and water is the same.
But some recipes call for different hydration rates based on what you are making.
- Lower hydration (50-70%) starters are firm and great for recipes that need to be kneaded a lot and hold a shape well (think challah and bagels) and tends to make dough that is not very sticky.
- Higher hydration starters (125%) are more watery, and allow the starter to eat through its food supply faster. These are easier to mix, but they tend to be stickier doughs, and generally don't hold up well to a lot of kneading (instead you can stretch and fold), but they also tend to need longer baking times.
Fg + (SH% * Fg) = SRG
where Fg= flour weight in grams, SH% is the starter hydration percentage (such as ).50 for a 50% starter hydration) and SRg = starter amount required by recipe in grams. Most recipes that don't use a 100% hydration call for either 50% or 125% hydration, so you can skip the math and use the following directions:
To change a 100% hydration starter to a 50% hydration
You need to feed it 1 part starter : 2 parts flour :1 part water
Feed it 120g flour and 100 g water.
Cover and keep on the counter, continuing to feed it 2 parts flour and 1 part water every 12 hours for 2 days.
Your 50% hydration starter is now ready to use.
To change a 100% hydration starter to a 125% hydration
You need to feed it 1 part starter:1 part flour: 2 parts water
Take 100 g of your 100% starter.
Feed it 100 g of flour and 125 g of water.
Cover and keep it on the counter, continuing to feed it 1 part water and 2 parts flour every 12 hours for 2 days.
Your 125% hydration starter is now ready to use.
Whatever hydration rate you keep your starter at is up to you, but just remember that you might need to make adjustments to your recipe when you use them.