- Yeast is a living organism indispensable to bakers. It is the agent responsible for leavening most breads. It is made under carefully controlled factory conditions, using just one of many strains of yeast. It is available in two basic forms:
- Compressed or “fresh” yeast, with a moisture content of about 70% and a shelf life of a few weeks
- Instant active dry yeast, vacuum packed with a moisture content of about 4% and a shelf life of up to a year if unopened. Once opened, it is good for several weeks if properly handled.
- The conversion ratios for the many brands of dry yeast are shown on the packages. They are about 1:3, dry to compressed.
- The functions of yeast are twofold:
- To create carbon dioxide to make the bread rise
- To mellow or improve the gluten
- When handling yeast, avoid warm temperatures. Don’t combine yeast with salt. Keep yeast in a cool place, near the freezing temperature. Keep it well wrapped, but allow space for breathing.
- Chemical leaveners include baking powder, baking soda, cream of tartar, and ammonium bicarbonate