Yeast– In baking, yeast, is used to leavened baked goods. The difference between yeast and baking powder/soda, is that these two latter ingredients react chemically whereas yeast is a living organism and the carbon dioxide it produces while feeding on the sugars and starches in the dough is what makes the doughs rise.
Yeast is available in compressed cake which is what most professioanl bakers use, but it does have a much shorter shelf life of just about 3 weeks after the date of manufacture, which doesnt leave much time for it to sit on the shelf at the grocery store. Fresh yeast needs to be stored in the refrigerator away from moisture, heat, and light because once yeast is exposed to air it deteriorates rapidly.
So we are much better off as home bakers to use dry yeast.
There are two types of dry yeast: regular active dry and rapid-rise. The two types of dry yeast can be used interchangeably. The advantage of the rapid-rise is the rising time is half that of the active dry and it only needs one rising. However, you do sacrifice flavor and texture in order to save time as the yeast does not have time to develop its own flavor.
When speaking of yeast in my recipes here I will always be using Regular Active Dry.
Yeast is temperature sensitive:
– at less than 50 F (10 C) the yeast is inactive.
– at 60 F – 70 F (15 C – 21 C) the yeast action is slow.
– at 90 F – 100 F (32 C – 38 C) the yeast is at its optimum temperature for fermentation.
– at greater than 104 F (40 C) the yeast action starts to slow.
– at 138 F (58 C) the yeast is killed.
1 package of dry yeast = 1 Tablespoon = 12 g
1 package of yeast will leaven about 4 cups of flour
1 package of dry yeast is equivalent to ½ ounce fresh yeast