Yeast is a single-celled living fungus that plays a crucial role in bread-making. It naturally exists in many environments and comes in various strains. In baking, yeast acts as a leavening agent helping dough rise by producing carbon dioxide (CO₂) and alcohol through a process called fermentation.
The Science of Fermentation
When yeast feeds on carbohydrates found in flour and sugar, it converts them into carbon dioxide and alcohol:
Yeast + Carbohydrates → Alcohol + Carbon Dioxide
- Carbon dioxide gets trapped in the dough’s gluten network, creating the airy structure that gives bread its rise and texture.
- Alcohol evaporates during baking, contributing to the bread’s flavor.
How Temperature Affects Yeast
Yeast is highly sensitive to heat and moisture. Its activity is directly influenced by temperature:
- Optimal growth: 75°F – 95°F (24°C – 35°C) – The ideal range for fermentation.
- Dormant state: Below 34°F (2°C) – Yeast becomes inactive but does not die.
- Death point: Above 138°F (59°C) – Yeast cells are destroyed, stopping fermentation.
The Role of Moisture & Salt
- Moisture activates yeast, allowing it to convert carbohydrates into food and fuel fermentation.
- Salt is essential in bread-making because it conditions the gluten, making it stronger and more elastic. It also controls yeast growth, preventing over-rising. However, too much salt can kill yeast leading to poor fermentation.
By understanding how yeast works, bakers can control fermentation, texture, and flavor, ensuring the perfect loaf every time.
Types of Yeast & How They Compare
Yeast comes in several forms, each with unique properties that affect fermentation, rising time, and ease of use. Understanding the differences helps bakers choose the best type for their bread recipes.
1. Active Dry Yeast
🔹 Most common type for home baking
🔹 Comes in granular form and requires proofing (activation) in warm water before use
🔹 Works best at 110°F (43°C) for activation
🔹 Slower fermentation compared to instant yeast
💡 Best for: Traditional bread recipes that require a longer rise
2. Instant Yeast (Rapid Rise / Bread Machine Yeast)
🔹 Finer texture than active dry yeast
🔹 Does not require proofing—can be mixed directly into dry ingredients
🔹 Ferments faster than active dry yeast, often reducing rising time
🔹 More reliable for consistent results
💡 Best for: Quick-rise breads, no-knead recipes, and bread machines
3. Fresh Yeast (Cake Yeast / Compressed Yeast)
🔹 Sold in a moist, block-like form
🔹 Highly perishable—must be refrigerated and used within a short time
🔹 Requires dissolving in water before mixing into dough
🔹 Preferred by professional bakers for strong fermentation and flavor development
💡 Best for: Artisan breads, commercial baking, and recipes requiring extended fermentation
4. Wild Yeast (Sourdough Starter)
🔹 Naturally occurring yeast cultivated in a flour and water mixture
🔹 Produces a distinct tangy flavor due to lactic acid fermentation
🔹 Requires regular feeding to maintain activity
🔹 Ferments more slowly than commercial yeast
💡 Best for: Sourdough bread, long-fermented breads, and unique flavor development
Which Yeast Should You Use?
| Yeast Type | Proofing Needed? | Fermentation Speed | Best Used For |
|---|---|---|---|
| Active Dry | Yes | Moderate | Traditional breads |
| Instant | No | Fast | Quick-rise recipes |
| Fresh | Yes | Strong & Flavorful | Artisan & commercial baking |
| Wild (Sourdough Starter) | Ongoing maintenance | Slow | Sourdough & rustic breads |
Can you use Fat Daddio’s bakeware for sourdough bread?
