Why does flaky pastry rise when baked?

The secret to the rise of flaky pastry lies in the clever layering technique used during its preparation. Flaky pastry comprises alternating layers of butter or a different kind of fat and dough. When the pastry is baked, the butter or fat melts, creating steam that separates the layers of dough and causes them to puff up. This rising action creates the distinct, flaky texture that gives flaky pastry its name.

This rising process is facilitated by several key factors:

1. Temperature Control:

A crucial element in making flaky pastry is keeping the butter or fat cold before baking. This prevents it from melting too quickly in the oven. When the cold butter comes into contact with the heat, it gradually melts and turns into steam, separating the layers of dough and making the pastry rise.

2. Lamination:

Lamination is the folding technique used to create the layers in flaky pastry. After each fold, the pastry is chilled, allowing the butter to resolidify and preventing the layers from merging completely. This ensures that there are distinct layers that can separate when baked.

3. Steam Production:

As the flaky pastry bakes, the melting butter or fat releases water vapor. This steam gets trapped between the layers of dough, pushing them apart and causing the pastry to rise. The steam also contributes to the pastry's flaky texture.

4. Rapid Expansion:

The combination of cold butter and heat from the oven creates a rapid expansion of the pastry when baked. The layers of dough quickly separate and puff up, giving the pastry its final height.

By precisely controlling the temperature, lamination technique, and steam production, bakers are able to create the perfect flaky pastry with its characteristic light, airy texture and distinct layers.