Leaven Breads

Leaven breads are naturally leavened loaves that use a mature starter instead of commercial yeast. They depend on a living colony of wild yeasts and lactic acid bacteria that convert sugars into carbon dioxide, alcohol, and organic acids. These compounds create distinctive aroma, flavor, and structure.

This intro summarizes terminology, core concepts, and best practices for using a leaven in bread formulas.

Glossary

Hydration Percentage

The hydration percentage is a calculation to clarify amounts recipes. The weight of water divided by the weight of flour, multiplied by 100. Hydration most noticeably influences fermentation speed and density.²³

• Below 65% is a low hydration percentage. Low hydration doughs like pain de mie are often tight, uniform crumb; ideal for sandwich loaves.
• 65-80% is a conventional hydration percentage range, common in standard artisan doughs like The Perfect Loaf's rustic country loaf.
• Above 80% is a high hydration percentage. High hydration doughs like ciabatta are often light, open crumb.

Leaven

A leaven or levain is a prefermented mixture built from the starter for a single-use recipe. It often contains flour, water, and a small inoculation of mature starter. Leaven is mixed at specific hydration and allowed to ferment before being incorporated into the final mix.⁴

Prefermented Flour Fraction (PFF)

A dough's prefermented flour fraction (PFF) is the proportion of total flour in the final dough that is fermented in the leaven. This metric is widely used to standardize formulas.

Wheat bread recipes typically use a 5-25% PFF according to Andrew Janjigian.⁵

Starter

A starter or mother culture is the ongoing yeast colony you maintain. It provides the microbial population that drives fermentation in the leaven and dough.⁶

Inoculation Rate

The inoculation rate is the ratio of starter to new flour in a leaven. For example, 10 g starter and 90 g new flour sums to 100 g, making the inoculation rate 10%. While the starter contains flour and water, you do not calculate the amount of flour in the starter; the inoculation rate uses the combined weight of flour and water in the starter.

A higher inoculation rate causes faster fermentation, milder acidity; a lower inoculation rate causes slower fermentation, deeper acidity.⁷

• A low inoculation rate of 2-5% encourages mild acid development over longer times.
• A common inoculation rate of 5-20% is common for many recipes.⁵
• A high inoculation rate of 20-30% speeds fermentation and somewhat increases acidity.

Reading a Baker's Table

Leaven formulas are expressed in baker's percentages, where total flour = 100 %. All other ingredients are listed as percentages of total flour weight. This allows scaling of any recipe while keeping ingredient ratios fixed. Danielle Ellis explains baker's percentages in detail.

Key Breadmaking Stages

Understanding each stage in leaven bread production helps control flavor, texture, and rise. Below is a typical sequence with emphasis on function:

1. Autolyse promotes gluten development, enzymatic activity, and dough extensibility.
2. Mixing and/or Kneading distributes microbes evenly, develops gluten network for structure.
3. Bulk Fermentation builds gas, flavor, and dough strength. Stretch-and-folds can be used to strengthen gluten without intensive kneading.
4. Shaping creates surface tension, partially degasses, prepares for final rise.
5. Proofing or Final Fermentation allows yeast to expand dough fully and lactic-acid bacteria to continue developing flavor; may occur at room temperature or in cold retardation.
6. Cold Fermentation slows yeast activity while allowing LAB to produce acids, enhancing tangy flavor without overproofing.
7. Scoring controls expansion, prevents tearing, and influences final loaf shape.
8. Baking produces the characteristic oven spring, gelatinization of starches, Maillard reaction for crust and color.
9. Cooling sets the crumb, redistributes moisture, and stabilizes flavor.