Yeast, the single-celled fungus that leavens, or...

Yeast, the single-celled fungus that leavens, or makes bread rise, is often sold in three forms.

Compressed yeast, also called cake yeast, must be refrigerated and has a maximum shelf life of about two weeks. It may also be frozen for up to two months, then defrosted overnight in the refrigerator before using. When fresh, compressed yeast is light grayish-tan in color and crumbles easily. It should be dissolved in water or milk between 80 and 90 degrees before being combined with the other recipe ingredients.

Active dry yeast, typically referred to as dry yeast, is usually preferred over compressed yeast because of its longer shelf life. The granules are packaged in airtight, moisture-proof packages, which may be stored for six months at room temperature and even longer when refrigerated. (The expiration date on the package is based on storing the yeast at room temperature.) One package of active dry yeast contains a scant tablespoon of granules. This amount is equal to a 0.6-ounce cake of compressed yeast.

Quick-rise active dry yeast is a highly active strain that makes bread doughs rise 50% faster than regular yeast. Although it may be dissolved in liquid, its fast-rising properties work best when added to the other dry ingredients. To activate it, the temperature of the liquids must be between 120 and 130 degrees.

Standard dry yeast is used in most common types of bread recipes. To activate the dry yeast, sprinkle it onto the surface of warm water that is between 105 and 115 degrees. The yeast dissolves in 3 to 5 minutes, then the mixture is stirred and combined with lukewarm milk, fat, sugar and salt.

Next, flour is stirred in, and the batter is beaten vigorously to begin developing the gluten (the elastic substance) in the wheat flour. Additional flour is stirred in to create a soft dough.

Kneading further develops the gluten and provides structure for the bread as it bakes. Many bread bakers enjoy the traditional technique of kneading bread by hand; however, a strong electric mixer with a dough hook or a food processor may also be used, following the manufacturer’s instructions.

For the hand method, turn the dough out of the mixing bowl onto a floured surface and form it into a fairly flat ball. Allow the dough to rest about five minutes.

Your kneading should be thorough but not rough. Develop a rhythmic pattern as the dough is worked, with time in between for it to relax. Rotate the dough a quarter-turn after each folding and pushing motion. Flours vary in moisture content, so it’s impossible to say exactly how much should be added during kneading.