Selecting the Right Grains and Flours for Sourdough

I’ve spent years experimenting with different flours, watching how each one behaves in my dough. Some ferment faster, others add complexity, and a few require extra hydration to get that perfect open crumb.

But here’s the truth: understanding grains and flour is like knowing your ingredients in a great dish. The better the quality, the better the result.

Let’s break it down.

Best Flour Types for Sourdough

The type of flour you use isn’t just about taste—it’s about how your dough ferments, stretches, and ultimately bakes. Not all flours are created equal, and sourdough is especially sensitive to grain quality.

Whole Wheat Flour: A Nutrient-Rich Workhorse

Whole wheat flour is like the sturdy backbone of sourdough baking. It contains all parts of the wheat berry—bran, germ, and endosperm—making it rich in fiber, minerals, and natural wild yeast.

Why Use Whole Wheat?

• Stronger Fermentation: The bran and germ contain natural yeast and bacteria that boost fermentation.
• Deep, Nutty Flavor: Whole wheat adds complexity and a touch of sweetness to your loaf.
• Higher Hydration Needed: Because of its fiber content, whole wheat absorbs more water than white flour.

That said, whole wheat can be tricky. It can make dough denser because the bran cuts through gluten strands. I often mix it with bread flour (about 30-50%) to get the best of both worlds—nutritional depth without sacrificing structure.

Rye Flour: The Fermentation Booster

Rye flour is a powerhouse for sourdough fermentation. It’s lower in gluten than wheat but packed with enzymes and sugars that wild yeast loves. If you want a robust, tangy sourdough with excellent rise, rye is your friend.

Why Use Rye?

• Enhances Starter Activity: Rye accelerates fermentation, making it a great choice for feeding your sourdough starter.
• Rich, Malty Flavor: It brings a deep, earthy taste with slight caramel notes.
• Moist, Tender Crumb: Rye bread tends to stay soft longer due to its pentosan content, which holds water better.

Because rye lacks strong gluten, a 100% rye loaf will be dense and hearty. Most bakers mix it with wheat flour (around 10-30%) to balance elasticity and flavor.

Ancient Grains: Tradition Meets Nutrition

Ancient grains—like spelt, einkorn, emmer, and khorasan—are the wild cousins of modern wheat. They bring unique flavors and a rustic quality to sourdough while being easier to digest than conventional wheat.

Why Use Ancient Grains?

• Complex Flavors: From nutty (spelt) to buttery (khorasan), each grain has its personality.
• More Nutrients: Higher in minerals like magnesium and zinc compared to refined flours.
• Lower Gluten Strength: Some ancient grains, like einkorn, contain weaker gluten, making them more digestible.

Ancient grains shine when blended with bread flour. A 20-40% mix will add depth without compromising structure.

How Flour Quality Affects Fermentation

Your sourdough is alive, and it thrives on the nutrients in flour. The better the quality, the stronger the fermentation. Here’s why:

Protein Content: The Gluten Factor

Gluten gives sourdough its structure. The protein content in flour determines how well your dough traps gas and rises.

• High-protein flour (12-14%) creates a strong, elastic dough—ideal for open-crumb sourdough.
• Low-protein flour (9-11%) results in softer, denser bread (like rye or pastry flour).

Bread flour is a reliable choice for structure, but blending in whole grains adds complexity.

Enzymatic Activity: The Fermentation Fuel

Flour naturally contains enzymes that break down starches into sugars—fuel for wild yeast. Some grains, like rye, are enzyme-rich, speeding up fermentation. Others, like white bread flour, are more neutral.

• High-enzyme flours (like rye) can lead to over-fermentation if not balanced.
• Low-enzyme flours (like refined wheat) ferment more predictably but lack depth.

Mixing flours helps regulate fermentation speed. I often combine rye for activity, whole wheat for nutrients, and bread flour for structure.

Ash Content: A Hidden Quality Marker

Ash content refers to the mineral content left behind after burning flour. Higher ash flours (like stone-ground whole wheat) contain more nutrients, which improve fermentation and flavor.

• Low-ash flours (like white flour) yield mild, airy loaves.
• High-ash flours (like whole wheat or Type 85) create richer, more complex sourdough.

For deep flavor and strong fermentation, look for organic, stone-ground, or minimally processed flours.

Final Thoughts

The flour you choose defines your sourdough. It’s not just about what makes the dough rise—it’s about flavor, texture, and how the fermentation unfolds. Whether you go for whole wheat’s hearty depth, rye’s tangy boost, or ancient grains’ rustic charm, understanding your flour is the key to crafting exceptional bread.

Experiment, take notes, and most importantly—enjoy the process. After all, sourdough isn’t just baking; it’s a relationship with the ingredients, the microbes, and the hands that shape it.

This article is part of the "Mastering Traditional Sourdough Baking" series.