How does yeast effect bread dough?

Yeast plays a crucial role in bread dough, transforming it from a simple mixture of flour, water, and other ingredients into a light and airy loaf. Here's how:

1. Fermentation:

* Yeast eats sugar: Yeast consumes sugars present in the flour (and sometimes added sugar) as fuel.

* Production of CO2 and alcohol: As yeast metabolises sugar, it produces carbon dioxide (CO2) gas and alcohol as byproducts.

* Dough expansion: The CO2 gas gets trapped within the gluten structure of the dough, causing it to rise and expand.

2. Flavor and Texture:

* Flavor development: The alcohol produced during fermentation contributes to the characteristic flavor of bread.

* Texture improvement: The CO2 bubbles create air pockets within the dough, resulting in a lighter and more airy texture.

* Crumb structure: The gluten strands, strengthened during kneading, trap the gas bubbles, forming the open and airy crumb that characterizes good bread.

3. Other Effects:

* Improved digestibility: The fermentation process breaks down complex carbohydrates, making the bread easier to digest.

* Enhanced nutritional value: Some studies suggest that yeast fermentation can increase the bioavailability of certain nutrients in bread.

Types of Yeast:

* Active Dry Yeast: Needs to be rehydrated before use.

* Instant Yeast: Can be added directly to dry ingredients.

* Fresh Yeast: Available in blocks and requires refrigeration.

Factors Affecting Yeast Activity:

* Temperature: Yeast thrives in warm temperatures (75-85°F).

* Sugar: Yeast needs sugar for fuel.

* Moisture: Yeast needs moisture to activate and ferment.

In short, yeast is the magic ingredient that makes bread rise, develop flavor, and achieve its characteristic texture.