The Measurements To Consider Before Swapping Dry Yeast For Fresh

In the world of bread baking, everything is powered by yeast, a fungus that consumes sugar and makes airy bubbles of carbon dioxide and flavorful byproducts. Today, dried yeast, whether active or instant, reigns supreme as the ultimate choice for bakers. But back in the day, fresh yeast, also known as cake or compressed yeast, was a mainstay of commercial and home baking. 

Sold in solid blocks, fresh yeast is the hydrated version of dried yeast, with each block containing about 70% moisture and fresh yeast cells. It can resemble a beige-colored rectangle of firm tofu, crumbling and breaking apart like feta. Unlike dried yeast, fresh yeast is sold in the refrigerator section of stores and has a shelf-life of only two weeks. For these reasons, it's a rare ingredient to come by and very rarely called for in recipes — so why worry about it at all? 

As fresh yeast was the yeast of choice in the olden days, many heirloom recipes call for it, rather than the modern dried yeast. So with that in mind, it's important to know how to translate fresh yeast into dried yeast. Luckily, this is easily done as long as you keep two ratios in mind: 1:3 for instant yeast to cake yeast, and 1:2.5 for active yeast to cake yeast. 

Breaking down the different yeast ratios

To understand the ratio between dried yeast and fresh yeast, you have to go back to the amount of moisture within the fresh yeast. The excess water in the fresh yeast means it weighs more than the dried yeast, so when translating the two, you have to go by weight, not by volume. 

Most blocks of fresh yeast are sold in either 0.6-ounce or 2-ounce sizes. From there, you'll take however much of fresh yeast called for and divide it by 3 if using instant yeast or by 2.5 if using active yeast. So if a recipe calls for ½ a block of a 2-ounce fresh yeast package (1 ounce or 21 grams), you'll use 2 ¼ teaspoons (7 grams) of instant yeast or roughly 2 ½ teaspoons (8.4 grams) of active yeast.  

This math is easy to do as long as you have a phone and a scale. If you're an avid baker, be sure to invest in a scale since this can help you with accuracy and consistency as well as minimize cleanup since you no longer have to use multiple measuring cups and spoons.