- By Janette Speyer
Yeast is a single-cell fungus that drives fermentation and allows a loaf of bread to rise. That delicious, sponginess comes from the yeast's leavening ability. Also, fermentation allows for the development of gluten essential for the bread's flavor. In this Storyboard, I'll cover everything you need to know about yeast. What is it? Where it all started, and some recipes. Happy cooking!