What does egg do in choux pastry?

Eggs play a crucial role in choux pastry, contributing to its unique texture and lightness. Here's how:

1. Hydration and Binding: Eggs add moisture and act as a binding agent, helping to hold the flour and water together. This forms a smooth, cohesive dough.

2. Structure and Elasticity: The proteins in eggs coagulate during baking, providing structure to the pastry. This helps create the hollow, airy interior characteristic of choux.

3. Rise and Expansion: As the eggs cook, they expand and create steam, which helps the choux pastry rise and puff up.

4. Flavor and Richness: Eggs add a subtle, savory flavor and contribute to the overall richness of the pastry.

5. Flexibility: The addition of eggs makes the dough more pliable, allowing it to be piped or molded into various shapes.

In summary, eggs are essential for:

* Hydration and Binding: Holding the dough together

* Structure and Elasticity: Creating a sturdy, airy interior

* Rise and Expansion: Helping the pastry puff up

* Flavor and Richness: Adding depth to the taste

* Flexibility: Enabling shaping and piping

Without eggs, choux pastry would be dry, dense, and lack the iconic hollow texture.