Why is yeast used for bread?

Yeast is used for bread because it's a tiny, single-celled organism that performs a magical trick: it eats sugar and produces carbon dioxide and alcohol as byproducts.

Here's how it works:

1. Yeast is added to the dough. The yeast finds sugar in the flour, either naturally present or added.

2. Yeast eats the sugar. This process is called fermentation.

3. Yeast produces CO2. As the yeast feasts on the sugar, it releases tiny bubbles of carbon dioxide gas.

4. The CO2 bubbles get trapped in the dough. This causes the dough to rise and become light and airy.

5. The alcohol evaporates during baking. The alcohol produced by the yeast is mostly evaporated during the baking process, leaving behind the airy texture we love in bread.

So, in short, yeast makes bread rise because it produces CO2, which makes the dough fluffy and delicious!