How does steam make a cake lighter?

Steam doesn't directly make a cake lighter, but it plays an important role in the process that does: leavening.

Here's how it works:

1. Leavening Agents: Cakes use leavening agents like baking powder or baking soda to create air pockets in the batter. These air pockets are what make the cake rise and become light.

2. Heat and Steam: When the cake bakes, the heat causes the leavening agents to react and produce gas (usually carbon dioxide). The steam generated from the moisture in the batter helps expand these gas pockets, further contributing to the cake's rise.

3. Structure: As the cake cools, the structure of the gluten in the flour sets, trapping the air pockets and giving the cake its airy and light texture.

In short, steam isn't the primary cause of a cake's lightness, but it acts as a crucial facilitator by:

* Expanding the air pockets created by leavening agents

* Helping the cake to rise more effectively

Without steam, the cake would be denser and less airy.