One question I receive most often goes like: “How do I control the sourness in my bread?” Some bakers want an assertive, mouth-puckering tang that makes sourdough, well, sour. Others prefer a milder, more nuanced acidity that lingers in the background (I’m usually in this camp). Thankfully, sourness is something you can control at nearly every stage of the breadmaking process to dial in your loaves just how you want ’em.
Over years of baking, I’ve come to understand that the “sour” in sourdough is really the result of a conversation between time, temperature, and the microorganisms living in your starter. Once you understand how these factors interact, you can push your bread in whichever direction you prefer.
Now that I’ve written and codified this guide, I look back on my baking over the past decade and realize I’ve kind of made these decisions instinctively to alter my bread’s flavor profile. If you’re a frequent reader here, you’ll see the same themes running throughout (e.g., young, fast levain for mild flavor; super-ripe levain and more whole-grains for more sourness, etc.).
In this guide, I’ll share what I’ve learned, both from the science side and from the countless loaves I’ve baked in my own kitchen, to help you adjust the sourness of your sourdough bread.
Keep in mind that there are many ways to increase/decrease sourness, and these are the steps I use in my baking.
Real Quick: Sourdough Sourness at a Glance
| To Increase Sourness | To Decrease Sourness |
|---|---|
| Use starter past its peak ripeness (collapsed, strong sour aroma, loose consistency, frothy) | Use starter/levain at peak ripeness (risen, mild sour aroma, some small bubbles) |
| Extend cold proof (24-48+ hours) | Shorten cold proof (10-12 hours) or skip it |
| Use a stiff levain (50-65% hydration) | Use a liquid levain (100% hydration) |
| Ferment warmer for more total acid (78-82°F) | Ferment cooler and shorter for less total acid |
| Increase whole grain percentage (especially rye) | Use more white flour |
| Let levain ripen longer | Use a young levain |
| Use a smaller levain (10-15% pre-fermented flour) | Use a larger levain (25-35% pre-fermented flour) |
Now, let me explain why these adjustments work and share what I’ve learned about the fascinating science happening inside your dough.
A loaf striking a nice balance between even, open structure and a subtle, sour tang.
The Science of Sourness in Sourdough (In Brief)
Before we get into the practical adjustments, it helps to understand what’s actually creating that sour flavor. The tang in sourdough comes primarily from two organic acids produced during fermentation: lactic acid and acetic acid.