The importance of fermentation

Perhaps one of the most significant trends for pizza makers in recent years has been the experimentation with different fermentation techniques. In “The Bread Bakers Apprentice,” Peter Reinhart states that “fermentation is the single most important stage.” Understanding how to manipulate time by using a starter will give you a new and effective tool in your pizza-making kit.

John Arena, owner
Metro Pizza, Las Vegas

For the purposes of pizza making we generally choose between two types of fermentation: commercial yeast fermentation that uses either fresh, dry active or instant yeast; or natural biological fermentation, which utilizes wild yeast captured in the air. It is important to understand that the difference in flavor is not primarily provided by the type of yeast itself, but is mainly provided by combinations of local bacteria as they feed off of the sugars in the dough. This is why sourdough starters from different locales produce distinctly different flavors and even textures. By capturing and cultivating starters from different places you can create unique pizza or bread dough that will provide your guests with an interesting back story that can distinguish your pizzeria from the rest of the pack.

In addition to creating unique flavor profiles there is a very practical reason that you should consider incorporating a starter in your pizza dough. Pizza makers have been extending fermentation time to develop complexity of flavor in their dough. For some of my pizzas I use a five-day cold fermentation process. The fact is my pizzerias are large and designed with ample cold storage for this very purpose. Many pizzerias simply don’t have the space to store a five-day supply of dough. Using a starter or a pre-ferment can help you create complex flavors and aroma without extremely long fermentation.

A starter is alive and must be treated as such. It needs to be cultivated and nourished. Some bakeries in San Francisco have been perpetuating a starter for over 100 years. Before we begin to make our starter it must be noted that simply mixing commercial yeast into a slurry such as what is used in a biga or poolish will not produce a viable starter that can be kept alive and used for extended periods. During the fermentation process bacteria develops. This contributes to flavor in the form of lactic and acetic acid. Unfortunately, commercial yeast cannot survive in a highly acidic environment. Wild yeast captured in the air thrives in an acidic environment.

Making a starter:

Combine 10 pounds of pizza flour with 10 pounds of rye flour. This will be your starter base.

Place one pound of your flour mix in a clean bowl and combine with one pound of warm water (90 F). Using your hands, mix into a smooth batter. Cover the bowl with a cheesecloth or towel and place the mixture in a cool spot in your kitchen. Now leave it alone for three days and let nature do its magic. The yeast and local bacteria in the air, on the wheat, and even on your hands has now been given an environment in which it can thrive and multiply, creating a unique starter.

After three days, bubbles should start to form on the surface of your starter. Give it a quick stir, breaking up any crust that may have formed on the top of the mixture. In this first stage the batter will be quite pungent. Don’t worry, it will mellow out. You can now feed your starter for the first time. Discard 24 ounces of your starter and replace with 12 ounces of room temperature water and 12 ounces of your flour mixture. Mix well. Cover starter again and wait 24 hours. Repeat this discarding and feeding process for seven days. After seven days you can begin building up your starter. Add one pound of flour mixture and one pound of water. Repeat this process for three more days and you will have 10 pounds of starter. Continue until you have an adequate amount of starter to service your volume of dough production. Store your starter in a cool place, always replenishing what you have taken from your supply and refreshing by discarding up to 20 percent of the starter every few days. Replace with equal amounts of flour and water. Your starter is not as fragile as people sometimes believe and can go a few days without eating.

As the starter sits, it will produce yeast and acid (but not at the same rate). The yeast will multiply faster than the acid will be produced, so a starter may be lively and active but may not be highly sour if it has been recently fed. Like any living entity, your starter is constantly evolving and developing. As you maintain your starter you will become attuned to its constantly changing nature. You must choose when to use it after feeding based on your flavor preference.

I like to combine both starter and fresh yeast in my dough recipe for a lighter, airier dough. Here is a simple formula using your newly created in-house starter:

45 pounds high-protein pizza flour

10 pounds of starter

26 pounds of water (68 F)

2 ounces fresh yeast (or 1 ounce Instant Dry Yeast)

1.25 pounds Kosher salt

1 pound extra virgin olive oil

Place water in mixer. Add fresh yeast and dissolve (if using instant yeast, add it on top of flour, keeping yeast away from salt). Add starter and whisk thoroughly.

Add flour. Add salt on top of flour.

Mix on slow speed for three minutes and then begin slowly adding olive oil, mixing for an additional six minutes until oil is completely absorbed into flour. Dough should feel smooth but not oily. Place dough on table and cover, allowing dough to relax for 10 minutes. Divide dough into balls and round gently. Place each dough ball on trays or containers, brushing with olive oil. Cover dough balls and refrigerate for 24 hours. Remove dough from refrigerator and allow it to reach 60 to 65 F before baking. 

John Arena owns Metro Pizza in Las Vegas.