By Allrecipes Staff

A step-by-step tutorial for making sure your yeast is still "alive" and ready to bake with.

Photo by Valerie's Kitchen

If you are a seasoned bread maker, you know all yeast needs to multiply and grow in a sympathetic environment. The correct environment includes moisture, food (in the form of sugar or starch), and a warm, nurturing temperature.

Whenever you intend to bake with active dry yeast, it is a good idea to test to make sure the yeast is alive. The act of testing to see if yeast is alive is called proofing. (Proofing rapid rise or instant yeast is not recommended.)

If the yeast you have in your cupboard is dead, no amount of environment will help it become a productive leavening agent.

VIDEO: See How to Proof Yeast

1. We used 1/2 cup water, 1 tablespoon white sugar, and one package of yeast for this test. This test is effective for either compressed fresh cake yeast or with dry active yeast. Cake yeast, being more perishable, should definitely be given this test if it has not been used in a while.

2. Heat the water to approximately 100 degrees F (40 degrees C). We recommend testing the water temperature using a thermometer.

3. In a nutshell, yeast eats various sugars and excretes alcohol and carbon dioxide. Alcohol and carbon dioxide are what the pockets in bread are filled with as bread bakes. Whisk the sugar into the water to help it to dissolve quickly.

4. Once the sugar has been evenly distributed throughout the water, add the yeast.

5. Stir the yeast into the warm sugar water.

6. After 5 or 10 minutes, the yeast should begin to form a creamy foam on the surface of the water. You can now proceed to combine the yeast mixture with the flour and other dry ingredients. If there is no foam in the bowl, the yeast is dead and you should start over with a new packet of yeast.