Sourdough Bread Formula

This is the formula we have been working with at the mill for several years. When you see our Instagram posts, this is the method we are using. You’ll find it closely mirrors some standard and well-known recipes, but with higher hydration and salt, and shorter bulk fermentation time – all important factors when working with whole grain flour.

Scroll down to the end of the post if you’d like to get right to the recipe. For additional insight, start here with some guidelines that will help you achieve successful outcomes.

About Flour
Stone milled, whole grain flour will never perform in exactly the same way as refined white bread flour. It just won’t. But if you are here and if you have purchased some Grist & Toll flour, I want to congratulate you on at least being open to exploring a new way of approaching flour and bread. There is so much for you to discover and I hope you enjoy the journey. However, even when all the stars align this formula will not yield the white, tall, fluffy loaf of bread with half dollar-sized air pockets. Beware the false Instagram posts proclaiming “whole grain” and “whole wheat” sourdough loaves that look incredibly white and have such an open crumb structure you wonder where your butter and jam will go! If it looks white, it is. Unfortunately, the word “whole” is used very loosely these days and is the source of great confusion and frustration for consumers and home bakers.

What you can achieve with this formula, and by using properly milled whole grain flour, is a beautifully structured loaf with a soft, open crumb, unparalleled flavor, and excellent keeping qualities. No doorstops here! As with any kind of baking, practice and repetition will help you gain confidence and produce brag-worthy bread. Is there a world where bread is delicious and impressive and not made from sifted white flour? One hundred percent!

The whole grain flours most regularly milled and stocked at Grist & Toll all work with this formula and you can (and should!) make 100% loaves with any the following: Hard Red, Hard White, and whatever heirloom wheat we have in inventory such as Red Fife, Rouge de Bordeaux, Wit Wolkering, or Chiddam Blanc de Mars. Pay attention to any insight we give you via blog posts, our Current Selections web page or in our retail shop regarding hydration percentages, gluten strength, etc. The older wheat varieties will almost never give you the same oven spring as the modern hard wheats, but they more than make up for it in flavor and character. Don’t be afraid of them. Your loaf may not be as tall, but with some practice your crumb will still be open and soft.

About Hydration
This working formula uses 425 to 450 grams of water for 500 grams of flour. Depending on the hydration of your sourdough starter, this puts you somewhere between 82-84% hydration (We include the levain in our hydration calculation. That percentage is higher when strictly comparing the flour to the water in the dough mix). As a general rule of thumb, always start with the lower amount of water for heirloom wheat varieties. They tend to be a little weaker in gluten strength and too much water can be tough for them to handle. Spelt is even more of an exception here as it has great extensibility, but lower snappy gluten strength. You should go even lower than 425g water for a 100% Spelt loaf, more like 375g. If our flour notes specifically state that a particular harvest of wheat is thirstier than normal, you can confidently choose the higher hydration amount and use 450 grams of water as your starting place.

Also remember that while all of these flours will work either alone or blended together, they don’t all look and feel the same during the process. Some doughs will start out feeling a little stickier and perhaps not as silky until the final stretch and fold. Spelt is particularly extensible, so much so that I am always worried I haven’t built enough tension and strength during the bulk fermentation, but it always pops up like a champ during the bake. If you’re ever worried about structure, you can always add a 4th stretch and fold during the final hour of bulk fermentation. Your dough will tell you right away whether or not this is a good idea: if you can’t stretch the dough without ripping or tearing it, let it be

About Starter
We keep a whole grain starter at the mill that is somewhere between a stiff starter and a liquid starter. However, we always feed that starter a higher ratio of flour to water (a stiff ratio) for the production levain build before our mix. We have found that even when our starter has been stored in the refrigerator for a week or so without being fed or used, we can pull it out in the morning, feed it this ratio and 4 hours later begin to mix our bread with excellent results. That specific ratio is given at the beginning of the recipe below. If you have neglected your starter for more than 2 weeks, you will need to revive it with at least a couple of feedings before baking.
*If you feed your starter our ratio of flour to water and don’t see impressive signs of activity in 4 hours (it should be growing and at very warm temperatures double in size when healthy), something else is going on. At best, it’s just really cold and fermentation is a little sluggish, which means it needs a little more time. At worst, your starter just isn’t active enough and you may need another feed and another day to get it going again.

If you already bake with a sourdough culture regularly and are perfectly comfortable with its cycle and hydration, simply substitute 100 grams of your active starter, fed and ready to go, and begin the mix. If you keep a liquid or high hydration starter, your overall hydration will be a couple of percentage points higher but that shouldn’t throw anything off.

About Timing
Things move along faster with fresh, whole grain flour. I am convinced that the majority of whole grain sourdough failures for home bakers revolve around time and temperature issues with the levain and dough proofing times, even more than just the sad fact that our home ovens will never be able to duplicate the intense steam and powerful heat of professional deck ovens. Baking with sourdough doesn’t give the same, obvious visual cues as bread leavened with commercial dried yeast, which so clearly doubles in size and tells us when it’s ready for the oven. It takes some time getting used to new fermentation clues. Controlling dough temperature from the beginning as much as possible and reducing the bulk fermentation time (during which you perform the stretch-and-folds) is critical, because the whole grain sourdough process tends to move along.

Desired Dough Temperature
Remember that cooler temperatures slow things down and warmer temperatures speed things up. I recommend a desired dough temperature (DDT) of 75˚F for a 100% Grist & Toll whole grain sourdough. When the weather is really cold, you know fermentation will be a little slower, so a warmer DDT of 80-82˚F is a good idea.

If you aren’t familiar with DDT, please do some online searches and reading for a deeper understanding. This is only a brief outline with a formula for calculating what your water temperature will need to be when you mix your dough. Because the whole grain sourdough process moves along more quickly, it is important that you pay attention from the beginning, and the only input you really have much control over is your water temperature.

If you are baking bread in Southern California in the middle of September with ambient temperatures hovering around 95˚F or above and the temperature of your dough is 85˚F after mixing all of your ingredients, you will be off to the races rather quickly, and the process can run away from you.

There are 4 things that directly impact the temperature of your dough:
• Your ambient room temperature
• The temperature of your levain/starter
• The temperature of your flour
• The tool you will use to mix your dough: either your hands or a machine
All of the factors above are basically out of your control – they are what they are. So, the one critical component missing – the water – is the only one you can directly influence.

Use this formula to calculate what your water temperature should be.
*You will need a good digital thermometer for this.
**A practical example will follow the formula.

• Multiply your DDT by 4 (because there are 4 temperature influencers)
• From this number Subtract the following
• The ambient room temperature (how hot/cold is it in your kitchen)
• The temperature of your levain/starter (Insert probe thermometer to get a reading)
• The temperature of your flour (Insert probe thermometer to get a reading)
• The Mix Factor: subtract 5 if mixing by hand, subtract 26 if using a stand mixer (hands generate and transfer much less heat to a dough during mixing than machines)
The resulting number will be the temperature your water should be. In hotter months, don’t be surprised if you have to add ice cubes to your measuring cup – water directly from the tap may not always be cool enough.

Example based on today’s real temperature readings at the mill, all in Fahrenheit.
DDT = 75

DDT 75×4 = 300

Ambient = 75 (it’s 75 degrees in my kitchen)
Levain = 73 (my starter has been sitting out for a while and is almost at room temp)
Flour = 71 (though stored at room temp, is actually slightly cooler)
Mix Factor = 5 (I’m mixing by hand, not in my Kitchen Aid)

Water = 76

From this exercise I know I need to adjust the water coming out of my faucet to be as close to 76˚F as I can get it.

And now that’s about as much as I can give you in one blog post to set you on the right path. What will help you more than anything is repetition and taking good notes. Try not to change multiple variables with each new bake. You must settle into the process and its rhythms in order to become attuned to all the subtleties that rule sourdough baking. Nothing is more exciting or challenging than how 3 simple ingredients – flour, water and salt – on any given day, can hand you the thrill of victory or the agony of defeat. Now, be fearless and go get it!


100% Grist & Toll Whole Grain Sourdough Loaf
Yield = 1 loaf

This is a two-day process:
From Levain Build to Shaping is about 7.5-8 hours followed by a 12-16 hour final cold proof overnight in your refrigerator.


Production Levain
150 grams starter
120 grams water (95 degrees if pulling starter directly from fridge)
200 grams Grist & Toll whole grain flour
*you will need 100g of this – the rest is extra and goes back in the fridge

100 grams Production Levain, from above
500 grams Grist & Toll whole grain flour
425-450 grams water
12 grams salt


1. Build Production Levain:
4 hours before mix put 150g starter, 120g water and 200g G&T flour in a bowl and mix completely. Cover with plastic wrap or a cloth and let ferment at room temperature.

2. Mix Dough:
DDT = 75 degrees F
In a large bowl, measure water and 100g production levain from above. Stir to break up and dissolve starter. Add flour and mix thoroughly to ensure all flour is hydrated. Dough will be shaggy and sticky. Use a dough scraper or stiff spatula to clean up your hands, the sides of the bowl and your dough.
Note: if you are worried about mixing in the salt later, it’s perfectly fine too leave out 25g of water from this initial mix and put it in a bowl with your salt to help it dissolve.

3. Autolyse (1 hour):
Cover bowl with plastic wrap or towel and rest/autolyse for 1 hour.

4. Bulk Fermentation/ Stretch & Folds (2 ½ hours):
-Add salt to dough and mix until integrated.
-Cover bowl tightly with plastic wrap or a towel
Perform 3 Stretch-and-folds, one every 30 minutes for the first hour and a half, so at 30 min, 1 hour, 1.5 hours. With each stretch and fold you should feel more tension in the dough, and it won’t let you stretch it out quite as far as the time before. Own the process but respect it. Really give your dough a good stretch, but don’t take it to the point of tearing or ripping. Let it rest with no folds for the final hour.

4. Shape:
Turn dough out onto a lightly floured work surface. There is no need for a bench rest if you are only making one loaf. When doubling or tripling the formula, divide dough, perform a rough shape and rest for 15 minutes. Shape and place in proofing basket/bowl. If using a bowl rather than a banneton, you will need to line the bowl with a flour sack towel or linen. Swaddle dough and banneton with a lint free towel. This is to keep the exposed dough from drying out during the final cold proof.

5. Proof:
Place in refrigerator for final long, cold proof 12-16 hours.

6. Bake:
45-60 minutes before baking, place a Dutch oven or cast iron bread pan in your oven and preheat to 500. Carefully remove heated cooking vessel, pull loaf directly from the fridge and carefully transfer dough into your hot pan, then score. Place cover/dome on, return to oven and bake for 30 minutes. Leave cover on*, but lower oven temp to 450 and continue baking for an additional 8-10 minutes, or until crust is richly colored and loaf sounds hollow when tapped on the bottom. Internal temperature should be around 208˚F. If it’s not quite done, you can leave the cover off for the final few minutes. Really let your bread cool before cutting, or the crumb will not be set and will be gummy.

*Unlike most sourdough recipes, I recommend leaving the cover on your bread during the entire bake. This is another distinction when working with 100% whole grain formulas: Whole grains brown faster and more deeply than white flour, so our goal is to prevent the crust from becoming too dark before the interior is fully cooked.

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