Yeast is a type of fungus used in baking, brewing and wine making. Via fermentation, it converts carbohydrates to carbon dioxide and alcohols. During the baking process the carbon dioxide emission fills the small pockets in dough and forces them to expand. This is how bread gets its airy texture.

I tend to work with SAF Red yeast. It’s an instant yeast. I store it in the freezer (you should too). It keeps over a year and can be used cold; no need to bring it to temperature.

Fresh Yeast is sold in cake form. It’s great to work with but doesn’t store well (about 10 days) and doesn’t perform well in bread machines. It’s also easier to kill, so mind your water temperatures. And if you kill the yeast, it won’t eat the sugar and produce the gas and the bread won’t rise.

Instant Yeast is usually sold in granulated form and is more finely ground in appearance than active dry yeast. It absorbs water faster than active dry and typically doughs made with instant yeast need only rise once.

Active Dry Yeast is also sold in granulated form. Doughs made with active dry yeast should rise twice to obtain the correct texture and flavor. Active dry yeast should be proofed. You will notice in many of my photos of recipes using yeast that I mix the dry ingredients, then form a well (pool for the liquid ingredients). In the well I put the yeast, sugar of some sort (milk powder, honey, sugar) and warm water. It sits for a few minutes and the liquid becomes bubbly. This is the proofing process. After the liquid is bubbly, it is mixed into the dry ingredients. Some people feel that breads made with active dry yeast, rather than instant yeast, have better flavor.

Instant yeast can often be used as a substitute for dry active yeast. But the recipe will need some adjustment. For example, you will need to add the water that would have been used to proof the yeast into the recipe.