What Makes Sourdough Bread Rise Without Yeast?

Sourdough bread rises because tiny living creatures called wild yeast eat the sugar in flour and burp out bubbles of carbon dioxide. These bubbles get trapped inside a stretchy net made of gluten, causing the dough to puff up like a balloon.

Unlike normal bread that uses a packet of dried, sleep-y sleeping yeast, sourdough relies on neighbors living right in your kitchen air and flour. These wild microbes wake up when you mix them with water.

The bacteria also help by making the mixture slightly sour. This sourness makes it hard for bad germs to move in, keeping the wild yeast happy and active. Over time, they multiply and create a strong team that works together to make your bread tall, fluffy, and tasty.