Yeast

A natural leavening agent which is activated by the addition of water. Most home bakers will use "active dry" yeast which is sold in powdered form in either packets or in bulk. Store yeast in either the refrigerator or freezer. Active-dry yeast will be activated when mixed in warm water (95-115°F). If the water is too cold or too hot the yeast will not activate. Rapid-rise yeast (also known as quick yeast) cuts the dough rising time in half, but the recipe does lose some flavor in the process. I don't recommend using rapid rise yeast unless a recipe specifically calls for it.