Tom Lehmann: In Lehmann's Terms

The Secrets of Instant Dry Yeast

Q: We normally use fresh yeast, but our supplier recently told us that only instant dry yeast will be available. We’ve never used instant dry yeast before. What do we need to know about this type of yeast when formulating dough for our pizza operation?

A: Instant dry yeast—or IDY, as it is commonly known—is typically used at 0.375% of the total flour weight. So if your dough is made using 40 pounds of flour and 1% compressed yeast (6.4 ounces), the amount of IDY used to replace the compressed yeast would be 2.4 ounces. Another way to look at it: You’ll want to use the IDY at 37.5% of the weight of compressed yeast that you are presently using. The best way to add the IDY is to just add it dry, right on top of the flour. No other changes need to be made.

One advantage of IDY is that it has a long shelf life—one year or more. Thus, it can be purchased by the case, possibly saving you some money on delivery costs at a time when every extra penny counts. It should be noted that IDY comes in vacuum-sealed bags. If the bag seal is intact, the bag will be as hard as a brick—and that’s a good sign. However, if the bag has been compromised in any way, it will be soft, and the viability of the yeast will be unknown. If you ever receive a soft bag of IDY, just return it and ask for an exchange.

Once you’ve opened the bag, do not transfer the IDY to another container. Instead, just roll the bag down upon the unused yeast and secure it with a rubber band. If you will be using the entire contents of the bag within a couple of days, I do not recommend placing the IDY in the cooler for storage. Instead, a better approach is to just store it at room temperature (65°F to 75°F). Why? Because when leftover IDY is refrigerated, there is a high probability that condensation will form on it in the bag, which can have a negative impact upon the viability of the IDY.

Finally, keep in mind that there are different types of IDY for different applications. The one that we use in the pizza and bread making industries is referred to as the red-label IDY.  

Tom Lehmann was the longtime director of bakery assistance for the American Institute of Baking and is now a pizza industry consultant.