Table of Contents
Sourdough Bread Fundamentals
Sourdough bread is the oldest form of leavened bread, dating back thousands of years to ancient Egypt. Unlike commercial bread that relies on packaged yeast, sourdough uses a naturally fermented starter culture containing wild yeast and lactic acid bacteria. This symbiotic ecosystem produces carbon dioxide for leavening, organic acids for flavor, and enzymes that break down gluten and phytic acid, making sourdough easier to digest than conventional bread.
The key to successful sourdough baking is understanding baker's math, also known as baker's percentages. In this system, all ingredient weights are expressed as a percentage of the total flour weight. The flour is always 100%, and everything else is relative to it. This makes scaling recipes simple and allows bakers worldwide to communicate formulas regardless of the measurement system they use.
A typical sourdough formula uses 75% hydration (water relative to flour), 20% starter (also called levain), and 2% salt. These percentages can be adjusted to change the bread's characteristics. Higher hydration produces a more open crumb with larger holes, while lower hydration creates a tighter, more uniform crumb. More starter speeds up fermentation, while less starter extends it and develops more complex sour flavors.
Baker's Math for Sourdough
The starter is typically maintained at 100% hydration (equal parts flour and water by weight), so it contributes both flour and water to the final dough. The calculator accounts for this dual contribution to maintain accurate hydration levels.
Hydration Guide
| Hydration | Dough Character | Crumb Structure | Difficulty |
|---|---|---|---|
| 60-65% | Stiff, easy to shape | Tight, sandwich-style | Beginner |
| 65-72% | Moderate, versatile | Medium, even holes | Intermediate |
| 72-78% | Soft, slightly sticky | Open, irregular holes | Intermediate |
| 78-85% | Very wet, difficult | Very open, large holes | Advanced |
| 85-100% | Batter-like (ciabatta) | Extremely open | Expert |
Baking Schedule
- Day 1, Evening: Feed your starter 8-12 hours before mixing. It should be at peak activity (doubled in volume, domed top, bubbly throughout) when used.
- Day 2, Morning: Mix flour and water (autolyse) for 30-60 minutes. Add starter and salt. Perform 3-4 sets of stretch and folds during the first 2 hours of bulk fermentation.
- Day 2, Afternoon: Bulk fermentation continues for 4-6 hours total at room temperature (75-78 degrees F). Dough should increase 50-75% in volume.
- Day 2, Evening: Pre-shape, bench rest 20 minutes, final shape, and place in a banneton. Refrigerate for 12-16 hours cold retard.
- Day 3, Morning: Preheat oven with Dutch oven to 500 degrees F. Score and bake covered for 20 minutes, then uncovered at 450 degrees F for 20-25 minutes until deep golden brown.
Frequently Asked Questions
How do I know when bulk fermentation is done?
Look for a 50-75% increase in volume, a domed surface with visible bubbles, and a jiggly, airy texture when you gently shake the container. The dough should feel lighter and more aerated than when you started. Under-fermented dough produces dense bread with tight crumb, while over-fermented dough is slack, difficult to shape, and produces flat loaves with a sour taste.
Why is my sourdough too sour or not sour enough?
Sourness is controlled by fermentation time and temperature. For more sour bread, extend the cold retard to 24-48 hours, use less starter (10-15%), and allow a longer bulk fermentation. For milder bread, use more starter (25-30%), keep fermentation at warmer temperatures (78-80 degrees F), and limit cold retard to 8-12 hours. The ratio of acetic acid (vinegar-like) to lactic acid (yogurt-like) also shifts with temperature.
What flour should I use for sourdough?
Bread flour (12-14% protein) is the best choice for most sourdough recipes as it provides strong gluten structure to support the open crumb. You can blend in 10-20% whole wheat or rye flour for additional flavor and nutrition. All-purpose flour works but produces a softer crumb. Avoid cake flour and pastry flour, as their low protein content cannot support proper sourdough structure.
How do I maintain my sourdough starter?
Feed your starter equal parts flour and water by weight (1:1:1 ratio of starter to flour to water) daily if kept at room temperature, or weekly if refrigerated. Discard all but 50 grams before each feeding. A healthy starter should double in 4-8 hours after feeding at room temperature and have a pleasant, yeasty aroma with mild tanginess.