What is sourdough made out of? The Essential Ingredients

According to the Encyclopedia of Food Microbiology, sourdough fermentation was the primary method of bread leavening for thousands of years. At its core, what is sourdough made out of comes down to a few surprisingly simple, natural ingredients and a living culture.

Quick Summary

Sourdough is traditionally made from flour, water, salt, and a fermented starter containing wild yeast and lactic acid bacteria. This slow fermentation process creates its characteristic tangy flavor and rustic texture, distinguishing it from regular commercial bread.

Key Points

• The Sourdough Starter: A fermented culture of wild yeast and bacteria is the key leavening agent, not commercial yeast.

• Simple Core Ingredients: Traditional sourdough is made from only flour, water, salt, and the starter.

• Longer Fermentation: A slow fermentation process, often lasting over 12 hours, is crucial for flavor, texture, and digestion.

• Improved Digestibility: Fermentation breaks down gluten and phytic acid, making sourdough potentially easier to digest and more nutritious.

• Variety of Flours: While all-purpose flour works, whole-grain or rye flour can be used for the starter to accelerate fermentation and add flavor.

• Natural Preservative: The acids produced during fermentation give sourdough its characteristic tang and extend its shelf life naturally.

• Flavor Complexity: The microbial diversity in the starter, influenced by a baker's technique, creates a wider range of flavors than commercial bread.

The Core Components of Sourdough

Unlike commercially leavened bread, which relies on a pre-packaged yeast, the magic of sourdough lies in its natural, multi-day fermentation process involving a handful of fundamental ingredients. The process begins with and is defined by the unique, living culture known as a sourdough starter.

The Sourdough Starter

Often called a 'mother' or 'levain,' the starter is a complex, living ecosystem of naturally occurring wild yeasts and lactobacillus bacteria that are typically collected from the environment and the flour itself. This fermented mixture of flour and water is the heart of any true sourdough loaf. Bakers must continually feed the starter with fresh flour and water to keep it alive and active. The wild yeasts produce carbon dioxide, which causes the dough to rise, while the lactic acid bacteria produce lactic and acetic acids, giving the bread its characteristic sour flavor and aroma. The careful nurturing and maintenance of this starter are what make each baker's sourdough unique.

Flour

The choice of flour significantly impacts both the starter and the final bread. While a basic sourdough recipe might call for high-protein bread flour, whole-grain flours like rye or whole wheat are often used to create and feed the starter initially. Whole grains are packed with extra nutrients and microbes that accelerate the fermentation process. Different flour combinations can lead to varied flavors, textures, and crumb structures in the finished product. For example, rye flour can produce a more pronounced tangy flavor and denser loaf, while all-purpose flour might result in a milder taste and a lighter crumb.

Water

Water is the solvent that activates the starter's microbes and hydrates the flour to form gluten. Using filtered water is often recommended by bakers to avoid the chlorine found in tap water, which can inhibit the growth of the beneficial wild yeasts and bacteria. The ratio of water to flour, known as hydration, also affects the final product, with higher hydration levels creating a more open, airy crumb structure.

Salt

Salt is added for a number of reasons beyond just flavor. It strengthens the gluten network, regulates the fermentation rate, and controls the activity of the wild yeast. Without salt, the dough can be sticky and unmanageable, resulting in a flat, poorly flavored loaf. The timing of salt addition is also important; it is often added after an initial rest period to allow the flour to fully hydrate.

Sourdough vs. Commercial Bread Ingredients: A Comparison

Feature	Traditional Sourdough Bread	Regular Commercial Bread
Leavening Agent	Naturally occurring wild yeast and bacteria from a fermented starter.	Industrially produced baker's yeast (Saccharomyces cerevisiae).
Fermentation Time	Slow, prolonged fermentation, often 12-36 hours or more.	Fast, a matter of hours or even minutes in industrial settings.
Key Ingredients	Flour, water, salt, sourdough starter.	Flour, water, salt, commercial yeast, plus potential additives like sugar, fats, or preservatives.
Primary Flavor Profile	Distinctive tangy or sour flavor derived from lactic and acetic acids.	Milder, often sweeter flavor with a distinct yeast aroma.
Nutritional Benefits	Higher nutrient bioavailability due to reduced phytate levels.	Lower nutrient absorption compared to traditional sourdough.
Crumb Texture	Rustic, chewy, and often more irregular with larger air pockets.	Soft, uniform, and consistently even crumb.
Digestibility	Often easier to digest for some individuals due to gluten breakdown during fermentation.	Can be less digestible for those with sensitivities.

The Science Behind Sourdough's Transformation

The simple ingredients of sourdough undergo a profound transformation during the fermentation process. The science involves a symbiotic relationship between yeast and bacteria, resulting in a more complex and digestible final product.

1. Phytate Reduction: Whole grain flours contain phytic acid, an anti-nutrient that can bind to minerals like calcium, iron, and zinc, preventing their absorption. The extended fermentation in sourdough, particularly with lactic acid bacteria, significantly reduces the levels of phytic acid, making these minerals more available for our bodies to use.
2. Increased Acidity and Shelf Life: The acids produced by the starter, primarily lactic and acetic, lower the dough's pH. This creates a less hospitable environment for spoilage-causing molds and bacteria, giving sourdough a longer natural shelf life without the need for artificial preservatives.
3. Complex Flavor Development: The diverse array of microorganisms in a starter, influenced by environmental factors like temperature and humidity, break down complex carbohydrates and proteins. This creates a wide range of flavor compounds that result in the unique, complex taste of sourdough, far beyond the simpler profile of commercial yeast breads.
4. Gluten Modification: The bacteria in sourdough starters produce enzymes that partially break down the gluten network during the long fermentation. While this doesn't make sourdough gluten-free, it can make it more tolerable for individuals with mild gluten sensitivity and contributes to the bread's distinctive texture.

What about enriched sourdoughs?

While the four core ingredients of flour, water, salt, and starter make a traditional sourdough, many variations exist. Bakers may add other ingredients to create different flavors and textures. Common additions include:

• Seeds and Grains: Adding seeds like sunflower or sesame and whole grains enhances flavor, texture, and nutritional value.
• Herbs and Spices: Ingredients like rosemary, olives, or spices can infuse the bread with aromatic and savory notes.
• Sugar and Fats: Some enriched sourdough recipes, like for panettone or Amish friendship bread, include sugar, honey, milk, or oil to create a sweeter, softer loaf.

Conclusion

Ultimately, what is sourdough made out of is a testament to the power of a few simple, natural ingredients. The combination of flour, water, salt, and a living, fermented starter creates a loaf with superior flavor, texture, and nutritional benefits compared to its commercially produced counterparts. The process requires patience and attention, but the result is a rewarding, complex, and highly digestible bread that connects bakers to an ancient tradition. Starting your own sourdough journey begins with understanding and appreciating these fundamental components and the miraculous fermentation they undergo.

The Science of Sourdough Starters - Serious Eats

Frequently Asked Questions

What are the four main ingredients in classic sourdough bread?

The four main ingredients in classic sourdough bread are flour, water, salt, and a sourdough starter, which is a living culture of wild yeast and bacteria.

How is sourdough bread different from regular bread?

Sourdough uses a naturally fermented starter for leavening instead of commercial baker's yeast, which results in a longer fermentation time, a distinct tangy flavor, and a more rustic texture.

Is sourdough healthier than regular bread?

For many people, yes. The fermentation process in sourdough can improve digestibility and nutrient absorption by breaking down phytic acid and modifying gluten, though it is not gluten-free.

Do I need to use a specific type of flour for sourdough?

While many types of flour work, a combination of whole-grain flour (like rye) and high-protein white flour is often recommended for creating and maintaining a robust sourdough starter.

What is the role of the starter in making sourdough?

The starter contains the wild yeast and beneficial bacteria that not only leaven the dough (make it rise) but also produce the acids that give sourdough its unique flavor.

What gives sourdough its sour flavor?

The sourness comes from the lactic and acetic acids produced by the lactobacillus bacteria during the fermentation of the sourdough starter.

Why does my sourdough recipe also call for commercial yeast?

Some modern 'sourdough' recipes add commercial yeast to speed up the process. This is often referred to as 'sourfaux' and doesn't achieve the same complex flavor or nutritional benefits as traditional, slow-fermented sourdough.

Can I make a sourdough starter at home?

Yes, you can create a sourdough starter from scratch by combining flour and water and allowing the naturally occurring wild yeasts and bacteria to colonize it over several days, with regular feeding.