Yeast is an essential ingredient in bread making as it causes the bread to rise. It is a living organism and requires food, moisture and warmth to survive. When dehydrated, it will remain dormant until it becomes activated during the process of fermentation. Yeast causes the carbohydrates (initially sugars) present to ferment and produce carbon dioxide (CO2). The CO2 becomes trapped in the dough by the network of gluten strands, causing the dough to rise.
Easy Bake Yeast
Dried Active Yeast