To substitute dry yeast in a recipe that uses cake yeast, use one package or 2 1/4 teaspoons of active dry yeast for every 0.6-ounce part of cake yeast. Cake yeast, also known as fresh yeast or compressed yeast, usually comes packaged in individual pressed cakes.
One standard packet, or 2 1/4 teaspoons, of active dry yeast is equal in baking to one cake of compressed yeast. Cooks can also substitute bread-machine yeast and instant yeast for cake yeast using the same measurement. All of these types of yeast function in the same manner, so the substitution is unlikely to have a noticeable effect on the texture of the finished product. Cake yeast tends to have a milder, sweeter flavor than active dry yeast, so it may be a better choice in desserts or delicate breads.
Cake yeast works faster and stays active for longer than dry yeast, but it is also more perishable than dry yeast. Fresh yeast stores in the freezer for up to four months. Due to its relatively short shelf life, this type of yeast may only be available seasonally. Cake yeast is ideal for commercial bakers who use large volumes of yeast at a time.