Why does flour need to be in sponge cake?

Flour plays a crucial role in sponge cake, but it's not just about providing structure. Here's a breakdown:

1. Structure and Texture:

* Gluten Development: Flour contains gluten proteins that develop when mixed with water. In sponge cake, the gluten development is minimal due to the gentle mixing and absence of kneading. This results in a delicate, light, and airy texture.

* Framework: Flour provides the basic framework for the cake to hold its shape. It traps air bubbles created during whipping, which contribute to the sponge's rise and airy texture.

2. Moisture Absorption:

* Flour absorbs moisture from the eggs and liquids in the batter, helping to create a cohesive mixture. This prevents the cake from being too wet and runny.

3. Flavor and Color:

* While not the primary source of flavor, flour adds a subtle sweetness and a pale, golden color to the cake.

4. Starch Gelatinization:

* The starch in flour gelatinizes during baking, which contributes to the cake's structure and its ability to hold its shape.

In summary: Flour in sponge cake is essential for:

* Creating a light and airy texture.

* Providing a framework for the cake.

* Absorbing moisture and creating a cohesive batter.

* Adding a subtle sweetness and color.

* Contributing to the cake's structure through starch gelatinization.

It's important to use the right type of flour for sponge cakes. Cake flour, with its lower protein content, is ideal as it produces a delicate texture.