Best Flour for Sourdough Starters and Sourdough Bread

Flour plays a pivotal role in sourdough baking, influencing the taste, texture, and nutritional profile of bread. The selection of flour for a recipe significantly impacts these characteristics. However, the wide array of options available in grocery stores can make choosing between different flours challenging.

In this post, I'll cover what you need to know so you can choose the best flour for sourdough starter and bread, helping you make confident choices so you can create the best baked goods.

Sponsored by Central Milling: I'm truly grateful for your support of the brands that help make Make It Dough possible. I want to assure you that all the recommendations and opinions expressed in this post are my own. 

What is flour?

Flour is a product made by grinding grains, seeds, and roots. The most widely used type of flour is made from wheat. To grasp the concept of flour, it's crucial to recognize that wheat comprises three main parts: the outer protective layer called bran, the starchy food source known as the endosperm, and the germ or embryo.

How is flour made?

In the U.S., the majority of flour is produced using roller mills, which crush grains of wheat between rollers or plates. Within this process, three components of wheat are separated. The white flour, such as all-purpose and bread flour, that is commonly sold on supermarket shelves is primarily made of the endosperm. These flours have a fine texture and mild flavor, making them versatile for various recipes. However, it lacks the nutritional richness of whole wheat flour due to the removal of bran and germ during processing.

Typically, whole grain bound for retail undergoes a process where the germ is separated, a step often taken to extend the shelf life of the flour. Following this, millers usually blend percentages of the bran and germ back into the white flour to create whole-grain flour.

Central Milling distinguishes itself among other mills by producing 100% whole wheat flour, ensuring that the entire wheat kernel, including the germ, is milled. This approach not only preserves the nutritional integrity of the wheat but also provides consumers with a product rich in essential nutrients.

What is a sourdough starter?

A sourdough starter is simply a mixture of flour and water. When left to ferment, this mixture becomes a thriving community of yeast and bacteria.

Through the process of fermentation, these microorganisms leaven bread and impart both the texture and flavor that make sourdough bread so delicious. A vigorous, healthy sourdough starter serves as the foundation of great bread, making caring for your starter culture one of the most crucial aspects of being a sourdough baker.

What distinguishes sourdough from commercial yeast is the remarkable diversity of microorganisms it harbors. While active dry yeast and instant yeast are primarily composed of Saccharomyces cerevisiae, recent studies have revealed that sourdough cultures may contain over 50 species of lactic acid bacteria and 20 species of yeast.

What is fermentation?

Fermentation is a biological process where naturally occurring yeast and lactobacilli bacteria present in the sourdough starter metabolize sugars in the flour to produce carbon dioxide and organic acids. 

What is gluten?

We can't discuss flour without highlighting its most remarkable attribute: the ability to form gluten. 

Gluten, is a general term for protein found in all types of wheat, barley, and rye.

It consists of two proteins glutenin and gliadin. When flour is combined with water or any liquid, these proteins bind together, initiating the formation of gluten.

Techniques such as kneading, stretching, folding, and shaping further encourage gluten strands to interconnect, resulting in the creation of a robust network that enhances the strength of dough.

What makes this gluten network remarkable is its ability to capture carbon dioxide. The stronger the network, the more it can stretch and expand, leading to taller, lighter baked goods. Additionally, as gluten is agitated, as in kneading or folding, it transforms texture, resulting in a chewier consistency. 

In addition to kneading and mixing techniques, selecting the appropriate flour with the right protein content is crucial for controlling gluten and achieving the ideal texture in baked goods. As bakers, our job lies in managing the formation of gluten in our baked goods. While a robust gluten network is ideal for baking Sourdough Focaccia, it can be detrimental to the soft and tender texture of a Sourdough Chocolate Muffin.

What is protein content? 

Protein content measures the ability of a specific type of flour to form gluten when mixed with water. This is usually expressed as a percentage; a higher percentage suggests that dough made with this flour can develop a stronger gluten network, while a lower percentage indicates a “soft flour” that is less capable of forming a strong gluten structure.

The type of wheat used to make flour typically dictates its protein level. Flours made from hard wheat varieties typically have higher protein level (11% to 13.5%) and are well-suited for bread baking, as they can produce a strong gluten structure necessary for bread's texture and rise. On the other hand, soft wheat varieties create low protein flours (9% to 10.5%) and are better suited for bakes, such as Sourdough Chocolate Cake and Sourdough Fruit Tarts, as they result in a delicate structure and tender texture.  

This is why using the exact type of flour a recipe calls for is extremely important. 

Understanding Flour Characteristics

Ash Content

Ash content in flour refers to the mineral residue left behind after burning a sample of flour at a high temperature. A higher ash content generally indicates a higher presence of bran and germ. This increases the mineral content and contributes to the flavor and nutritional value of the flour.

Ash content is commonly used to classify flours into different grades or types: whole wheat flour typically has a higher ash content (around 1.5%) compared to bread flour, which usually has a lower ash content (around 0.60%). As an example, Central Milling’s Organic Type 80 Wheat Flour boasts an ash content of 0.80%, with the name referring to the amount of bran and germ left in the flour. 

Variety

This typically indicates the color of the bran and the season in which the wheat is planted, such as Hard Red Spring Wheat. The color of the wheat affects its flavor profile, while the season of planting has implications for its hardness.

Color: White wheat, which contains no tannins, offers a milder flavor, whereas red wheat contains tannins that impart a slightly bitter taste.

Season: Winter wheat tends to be softer and is commonly used for all-purpose flour, while Spring wheat boasts a higher protein content and is often preferred for bread flour.

Malted

When a flour is labeled "malted," it indicates that it contains sprouted malt barley. Malted barley is a source of amylase, an enzyme that breaks down some of the flour's starch into sugars. These sugars serve as a source of nutrition for yeast, promoting fermentation.

I love Central Milling because they are one of the few flour companies that readily offer detailed information on their packaging and website. Founded and operated by passionate bakers, they have been leading efforts to educate both professional and home bakers about the significance of flour quality and its influence on our baking. You can shop their huge selection of high-quality flours online.

What is the best flour to use for sourdough?

While the type of flour we select will deeply influence the traits of our sourdough starter, determining the ultimate "best" choice remains elusive.

Different flour types will impart unique characteristics to our culture, but whether or not they are truly "the best" is ultimately subjective and dependent on individual tastes.

Exploring unique characteristics of different types can empower you to make a well-informed choice when selecting the right flour for both your sourdough starter and sourdough bread.

All-purpose Flour

Protein: 10.5% 
Ash: 0.55%

Perhaps the most common flour found in kitchens, all-purpose flour is incredibly versatile and can be used in a wide range of baked goods, from pillowy Sourdough Dinner Rolls to Sourdough Buttermilk Pancakes. It strikes a perfect balance of softness and structure, making it an ideal choice for various recipes.

Due to its wide availability and affordability, all-purpose flour is often my top recommendation for creating and maintaining a sourdough starter. In fact, I've been feeding my own sourdough starter Central Milling's all-purpose flour for the past 4 years.

Moreover, since many sourdough recipes, including the ones here on my blog, typically require an all-white starter, I've found that an all-purpose sourdough starter is also the most versatile option.

Bread Flour

Protein: 11.5%
Ash: 0.60%

Bread flour, also known as strong flour in many regions, earns its name from its high protein content, which makes it ideal for bread baking.

Dough made with this flour can develop a robust gluten network capable of stretching, holding its shape, and capturing gases produced during fermentation, resulting in light and airy bread. However, too much bread flour in recipes can often result in bread that is too chewy.

I often combine it with all-purpose flour to add extra structure to rustic loaves, such as Sourdough Cranberry Walnut Bread and Sourdough Lemon Rosemary Bread. However, it's important to avoid substituting this flour in recipes such as cakes, cookies, and pastries, as it may result in a gummy texture in the final bake.

While it's possible to create a sourdough starter using bread flour, it tends to be more expensive than all-purpose flour and offers very similar characteristics in terms of minerals and nutrients. For this reason, I generally do not recommend using bread flour for making a sourdough starter.

High-Protein Bread Flour

Protein: 13.5%
Ash: 0.60%

This high protein flour variety boasts even greater gluten potential than Bread Flour, making it perfect for recipes like Sourdough Pretzels and Sourdough Bialy, where the dough requires extensive stretching and manipulation. The end result is a bake with a satisfyingly chewy texture.

Whole Wheat Flour

Protein: 13.5%
Ash: 1.6%

Unlike white flour, whole wheat contains all three parts of the wheat kernel. It often has a higher protein content, which doesn't always lead to a strong gluten network. The bran in the flour has sharp edges that can cut gluten strands and impede the development of a strong network, resulting in denser bread.

Since whole wheat flour is high in fiber, it absorbs more water, so recipes using it may need extra liquids. This is why it’s crucial not to substitute whole wheat flour in recipes that don't call for it.

Whole wheat can make delicious bread and baked goods if used appropriately. That's why it's best to use a recipe specifically designed for it, such as my Sourdough Discard Whole Wheat Bread and Sourdough Discard Guiness Brown Bread.

Whole wheat flour is an excellent choice for creating a sourdough starter due to its nutrient-rich composition and potential for fostering a robust microbial community. However, it's important to note that the quality of whole wheat flour can vary between brands. As a result, your sourdough starter may develop unique characteristics in terms of aroma, texture, and consistency depending on the brand of whole wheat flour you use.

Rye Flour

Protein: 10.9%
Ash: 1.60%

Rye is a grass closely related to wheat and barley. Although it is not gluten-free, its protein content is significantly lower than that of wheat. Consequently, dough made with rye tends to be very sticky and slack. Rye bread typically has a denser crumb and a more pronounced sour flavor.

Among sourdough bakers, rye flour is widely recognized as a solution for sluggish starters that fail to rise. This is due to its abundance of amylase and other nutrients, which expedite the conversion of starches into sugar.

Research has shown that rye flour fosters much more biodiversity than any other type of flour, with over 30 types of bacteria thriving in mature rye starters.

Looking for a way to try out rye flour? Try my Sourdough Discard Marble Rye Bread recipe.  

Ancient Grains: Spelt Flour, Khorasan Flour and Einkorn Flour

Ancient grains refer to whole grains that have undergone minimal alteration through selective breeding over centuries. In contrast to wheat flour, which typically undergoes a process where its components are separated during milling, ancient grain flours are packaged with all parts of the grain, including the bran and germ. This preserves their nutritional value, making them richer in fiber and other nutrients.

Among the most popular varieties are Spelt, Khorasan, and Einkorn. Each of these grains possesses unique qualities that contribute distinctive characteristics to bread and other baked goods. Therefore, it's important to be mindful of them when experimenting. I've found that they make great additions to my bread formulas, and I often substitute them for small percentages of whole wheat flour.

Of these varieties, I have the most experience with spelt, and I personally love its naturally sweet flavor and tender texture. If you're interested in trying it out, be sure to check out my recipe for Spelt Sourdough Bread.

Rice Flour

The only gluten-free flour I use in my everyday baking is rice flour. I use it for preparing my bannetons and for scoring sourdough. Since rice flour doesn't have gluten, it doesn't absorb into dough which prevents dough from getting stuck to proofing baskets. Additionally, its tendency not to brown during baking makes it perfect for showcasing intricate scoring patterns. 

Flour FAQs