Cookbook:Preparing Yeast

This technique is also known as 'blooming'.

Though instant yeasts are now available which can be mixed directly with the dry ingredients in a recipe, many people find that this technique still improves the quality and rising times of bread. Proofing is also the easiest way to determine if an old packet of yeast is still viable.

Ingredients

½ cup (125 milliliters (4.2 US fl oz)) of warm water or other liquid reserved from the bread recipe
1 teaspoon of sugar
1 tablespoon of yeast, or as called for in the recipe
¼ teaspoon of ginger (optional)

Procedure

Make sure the water is warm and between 112 and 120°F (44 - 49°C). Hot water (above 49C/120F) could kill the yeast, and water above 60C/140F definitely will. Cold water will significantly slow yeast growth. A general guideline is to stick your finger into the water; if you find it warm and comfortable, so will the yeast.
Thoroughly stir the ingredients into the water, making sure everything dissolves properly (yeast, in some forms, is rather prone to forming clumps at the bottom). Let this mixture sit in a warm place until there is a bubbly froth on top. Depending on the type of yeast, this will take between 10 and 30 minutes, and should yield a "head" of at least one centimeter. Use as indicated in your recipe. If no bubbles develop, discard and obtain new yeast.

Yeast Cake Substitution

Many older cookbooks will often have recipes calling for a "yeast cake". This is a small cake of active yeast, often 0.6 ounces (17 grams) in weight. They are not normally used today since they are highly perishable and have a short shelf life, even when refrigerated (about 10 days). 1 Yeast Cake can be substituted with 1 packet or 2 1/4 teaspoons of Active Dry Yeast. To substitute a 2 ounce yeast cake, use 3 packets or 6 3/4 teaspoons of Active Dry Yeast.