As unappetizing as it sounds, the yeast used in pizza dough is a type of fungus that, given the right conditions, will multiply very quickly. Yeast is composed of many small cells filled with living matter called protoplasm. It is an essential ingredient in the making of pizza dough.
The Purpose of Yeast
Yeast is an essential ingredient in making pizza dough, because it makes the dough rise, giving it texture. Without yeast the dough would be flat and hard.
How It Works
When yeast is mixed with water, sugar and flour, it produces carbon dioxide. This is what makes the mixture "bubble," or rise, while it is in the oven.
To make pizza dough, the yeast is mixed with sugar, water and olive oil, before the baker gradually adds flour and stirs carefully. This mixture is then kneaded by hand, which helps to eliminate large air bubbles. The dough is then rolled out. It can be baked immediately or stored in the refrigerator, wrapped in cling film, until it's needed.
Types of Yeast
Different types of yeast are available for making dough: fresh yeast, which needs to be kept in the refrigerator; dried yeast, which comes in granules that are added to water and sugar before use; and easy yeast, a powder that comes in sachets and simply needs to be sprinkled into flour.
Shelf Life of Yeast
Fresh yeast can be kept for only one or two weeks. After this time it stops working, though it can be frozen for up to three months. Dried yeast can be kept longer. Abide by the use-by date on the packet, but it can usually be kept for several months at room temperature.