Yeast is a living organism that is used as a raising agent in bread and as an alcohol producer in wine and beer making. Traditionally it was used in its fresh form and, although this works stronger and longer than other types of yeast, it only has a limited shelf-life of up to two weeks in a refrigerator. Dry yeast however, can be kept up to a year in storage, and is less temperamental to use. It has therefore become the yeast of choice for many bakers. Recipes often give the quantities of fresh yeast required and it is useful to be able to convert these for a substitution of dry yeast. In this way, you will be able to use traditional recipes that have been handed down through the years.
Divide the number of grams of fresh yeast by 3 to calculate the amount of dry yeast. For example, 30g of fresh yeast divided by 3 equals 10g of dry yeast.
Multiply the number of grams of dry yeast by 3 to calculate the amount of fresh yeast. For example, 21g of dry yeast multiplied by 3 is 63g of fresh yeast.
Check your calculations. The quantity of fresh yeast will always be more than the amount of dry yeast.
Sachet sizes of dry yeast vary. However, one 7g sachet is the equivalent of 6 ml (2 tsp) of dry yeast or 21g fresh yeast.