By Tracy Morin

Yeast may not get all of the glory given to its pizza making counterparts, like flour and cheese, but it’s an essential part of the process. In fact, according to Luca Varuni, owner and maestro pizzaiolo at Varuni Napoli in Atlanta, it was once considered downright magical. “Humans have always used yeast—Egyptians used it 5,000 years ago and, because they were unaware of the fermentation process, they thought the chemical reaction was a miracle,” he recounts. “By 1996, the first complete genome of yeast was mapped.”

Clearly, in today’s world, yeast needn’t remain so mysterious. We tapped some bona fide baking experts to tackle all of the basics—and plenty of the intricacies—behind this key dough ingredient. In addition to Varuni, they include Paul Bright, senior innovation manager for AB Mauri North America in St. Louis, and Ralf Tschenscher, baking business development manager at LeSaffre Yeast Corporation in Milwaukee. Here’s what they told us:

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Q: What is the function of yeast, and what are the different types available?

Ralf Tschenscher: Yeasts are single-celled microorganisms classified as members of the fungus family. In the pizza industry, the most common yeast species used is Saccharomyces cerevisiae, a key ingredient in pizza baking. It derives its name from Latinized Greek, meaning “sugar fungus,” because it converts sugars and starches into alcohol and carbon dioxide during the fermentation process. The main function of yeast in pizza dough is to allow for leavening; allow the pizza dough to mature and improve the gluten structure; and enhance the flavor and aroma of the pizza crust. 

Paul Bright: There are two different types of bakers yeast: fresh (or wet) and dry. Fresh yeast is comprised of compressed or block yeast, sold in 1- to 5-lb. blocks. Dry yeast is available in active dry and instant forms.

“As fresh, active dry and instant yeasts are forms of the same species, they will all produce similar fermentation flavor, gassing activity and end-baked pizza texture when used appropriately.”
— Paul Bright, AB Mauri

 

Q: How should a pizza maker choose the right type of yeast for his operation?

PB: Choosing the right yeast depends on the pizzeria’s process and the dough maker’s preference or comfort level with using a particular yeast type. As fresh, active dry and instant yeasts are forms of the same species, they will all produce similar fermentation flavor, gassing activity and end-baked pizza texture when used appropriately. Here is a quick breakdown:

Fresh yeast can be used at any water or dough temperature and is the easiest to use of all yeast types. A negative of fresh yeast is that it has the shortest shelf life and generally needs to be used within weeks of purchase.

Active dry yeast (ADY) must be rehydrated for five minutes using a small portion of warm water (100° to 110°F) before adding to the flour. Once hydrated, the rest of the dough water can be at any temperature to achieve the desired finished dough temperature. If ADY is not rehydrated prior to adding to the mixing bowl, the yeast particles will not dissolve into the dough after mixing, resulting in a slow-proofing yeast. Unopened ADY has a two-year shelf life. Once opened, it should be transferred to an airtight container and stored under refrigeration for up to two months.

Instant dry yeast (or IDY) is designed to be added directly to dry ingredients and blended prior to the addition of water. Prehydration of IDY will result in a loss of gassing activity and slower-proofing doughs. Cold or ice-water temperatures should not be used for this type of yeast, as maximum yeast-activity water temperatures are 80°F or higher. IDY has similar shelf-life characteristics as ADY.

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RT: To answer this, ask yourself: What are your objectives—are you running a single-unit pizzeria or chain, working in a wholesale operation, involved in frozen dough production? What will your weekly usage be? Are you able to order yeast every week? This is almost essential if you are using fresh yeast.

From my experience, in North America, the majority of pizzaioli are using either IDY or ADY. One reason is usage level—compared with fresh or compressed yeast, IDY usage is 2/3 less, and ADY usage is half. Another reason is that IDY and ADY provide a much longer shelf life than fresh yeast.

“Deactivated yeast…reduces the mixing time and creates more extensible dough, which allows pizzaioli in training to stretch the pizza dough much more easily without tearing the pie.”
— Ralf Tschenscher, LeSaffre Yeast Corporation

Luca Varuni: The type of yeast and the amount you choose depends on what type of fermentation, timing and digestibility you want to give to your dough. At Varuni Napoli, we use what we call in Naples “lievito madre,” or “mother yeast,” which is a sourdough yeast. The mother yeast is essentially an acidic dough obtained by mixing flour and water. Fermentation can be triggered by leaving the flour and water exposed to the air and a whole series of exogenous bacteria and yeasts. Our mother yeast was originally made nine years ago, when I opened my first Varuni Napoli location. We also use a very small amount of fresh yeast along with our mother yeast to help the fermentation and the rising of the dough. 

For beginners, I would suggest ADY or IDY, but fresh yeast produces pizza dough with a little more flavor compared to dry yeast. If you are willing to take the challenge, you can give it a try with sourdough yeast, which will give flavor to your dough and produce a crust that’s slightly crispier on the outside, while the inside stays light and airy for a great texture experience.

“The type of yeast and the amount you choose depends on what type of fermentation, timing and digestibility you want to give to your dough.”
— Luca Varuni, Varuni Napoli

 

Q: What are some things to keep in mind when working with different yeast types? 

PB: When making formulation changes from one yeast type to another, use the following conversion rates to achieve similar gassing activities: 1 lb. of fresh = 0.5 lb. of ADY = 0.4 lb. IDY. When changing from fresh to dry yeast, increase water to make up for the water loss from fresh yeast. For example, if your formulation requires 2 lb. of fresh yeast and the pizzeria is changing to IDY, the conversion will be 0.8 lb. of IDY + 1.2 lb. of additional dough water.

Fresh yeast should always be stored at temperatures below 45°F. Also, fresh yeast should never sit unrefrigerated in the pizza shop for more than 30 minutes, as its warming will have a negative impact in yeast gassing activity, resulting in slow proofing times. 

RT: If you decide to produce frozen doughs and your objective is to achieve a very long freezer shelf life, we suggest using fresh yeast—it provides the best results in frozen pizza dough production. Also, there is another type of yeast, deactivated yeast or inactive yeast, which has gained significant popularity. What’s unique about deactivated yeast is that it reduces the mixing time and creates more extensible dough, which allows pizzaioli in training to stretch the pizza dough much more easily without tearing the pie. Note: The addition of conventional yeast is still required.

LV: The mixer should not impact what yeast you decide to use. At Varuni Napoli, we use only spiral mixers, which are gentler on the dough and prevent dough from overheating. But, depending on the type of yeast you use, you need to be careful of the way you add it to the mixer. For example, yeast does not love salt, and salt in direct contact with yeast will kill it. This will reduce the ability of the yeast to properly ferment the dough. Be focused when adding the yeast and the remaining ingredients to the mixer. If you add water, salt and yeast, then leave to have a glass of wine and come back later to add flour, your dough will not rise properly!  

Tracy Morin is PMQ’s senior copy editor and the editor of PizzaVegan.com.