There is no mystery about yeast, that’s why I wrote this article all about yeast, in order to clarify every question there is connected to this subject. In Germany you can buy fresh yeast at every supermarket or bakery. But not in the most parts of the USA. So here is a bit more about yeast in order to make it easier for you to use German recipes that require fresh yeast.
Fresh yeast is pressed into a cake or block and is also called compressed yeast. You use it for many cakes and pastries; it adds a nice subtle yeasty taste to the bread or cake. Dry yeast does not do this but it responds a little bit faster then fresh yeast.
How is fresh yeast made?
Fresh yeast is grown in a nutrient broth, the broth then is removed through centrifuge and the yeast is packed very tightly into small squares. It has a short shelf life of a few weeks, compared to months or even years (in the freezer) for dried yeast. Fresh yeast is more expensive than dried yeast and unavailable in many areas in the US. It is often used in bakeries.
In Germany, fresh yeast comes in 40 gram packages (about 1.5 ounces), enough to make 500 grams (1.1 pound) of white flour rise in about one hour. In the US, 0.6 and 2 ounce packages are sold (17 grams and 56 grams) in the refrigerated section (near the milk and butter).
Because fresh yeast has moisture in it, you should use 3 times the fresh yeast in weight for the same rising ability of instant yeast and 2.5 times the amount for active dry yeast.
Proof fresh yeast by crumbling it into warm water (110°F) with a pinch of sugar. Stir to dissolve. Wait ten minutes and check for foam building.
To use fresh yeast in a recipe, you can make a well in the center of the dry ingredients, crumble the fresh yeast into the middle, cover with warm liquids and stir up a little of the dry ingredients into the liquids. Wait until bubbles form, then continue mixing.
You may also dissolve fresh yeast in a little of your liquid and add it to the bowl with the rest of the liquids. Proceed as usual with kneading and proofing. Always soften or dissolve fresh yeast in liquids before mixing or it will not distribute evenly throughout the dough.