Choice of yeast correlates directly to finished pizza
Beans, beans, the musical fruit! The more you eat the more you toot!
Yeast might give beans a run for their money in the gas-production department, and rightfully so! For something so tiny, yeast packs a real punch – and where would we be without it?
Yeast is a very tiny member of the fungi family that is truly remarkable. For baking purposes, we mainly focus on the yeast Saccharomyces cerevisiae – often called baker’s yeast or brewer’s yeast because it also is crucial to fermenting beer and wine.
Like any living thing, yeast has two main goals: eat as much as possible and multiply. The main source of food for yeast is simple sugar. With the help of oxygen, yeast consumes sugar and creates carbon dioxide and water as a waste product, also known as respiration.
It is only when oxygen is no longer available that fermentation kicks in, and the byproduct changes slightly to carbon dioxide and ethanol alcohol. This is why, when a preferment is left unattended for too long, it develops a nasty-looking layer of dirty water and smells like alcohol. The yeast is slowly running out of food and oxygen.
During mixing, proofing, stretching, re-stretching, folding, shaping and all the stages we put dough through, yeast goes in and out of respiration and fermentation, but the limits aren’t endless. Although yeast does reproduce on its own if the food source is readily available and the environment is right, it’s not a forever thing.
Temperatures play a big role – as do hydration and high levels of sugar and salt. When I say high levels of sugar, I don’t mean the small amount of sugar some pizza makers use, but rather the enriched doughs you see in baking items such as brioche and sweet breads.
The lower the hydration, the slower dough ferments. Fermentation cannot happen without water, which plays several roles. I like to think about water like a lazy river you float down on an inner tube. Yeast and microbes ride the tubes down the lazy river, and the lower the hydration (aka, the lower the level of the river), the slower they go. The higher the hydration, the quicker things can move around, like tubing down Class VI rapids.
Four Main Forms of Yeast for Pizza
For pizza, there are four main forms of yeast we are concerned with: fresh block/compressed, instant dry, dry active and sourdough. Some characteristics of each are as follows.
1. Fresh Yeast
- Needs to be refrigerated
- 72% hydration
- Shelf life of two to three weeks after opening
How to use: Break it up and add straight into flour. Fresh yeast can be dissolved in water, although it’s not necessary.
Things to consider:
- Handling during shipping is not consistent, so fresh yeast often becomes damaged.
- The shelf life of fresh yeast is very short.
- Packages usually are not dated, so you can’t be sure of the fresh yeast’s age when received – especially if the packaging is ripped.
- Because of hydration, storage needs to be very precise, or it will mold, dry out and die quickly.
2. Instant Dry Yeast
- Refrigeration is optimal but not necessary if stored in a cool, dry place.
- 5% hydration
- Shelf life is two years sealed and unopened and one year refrigerated or frozen and airtight.
How to use: Toss directly into flour during dough mix; it also can be bloomed in water, although that’s not necessary.
3. Active Dry Yeast
- Refrigeration is optimal but not necessary if stored in a cool, dry place.
- 8% hydration
- Shelf life is one to two years unopened and airtight, or four to six months refrigerated or frozen and airtight.
How to use: Bloom in warm water not exceeding 100 F prior to dough mix.
4. Sourdough
The sourdough method requires a process to get started and then a feeding schedule to keep the starter alive and active. Flavors will evolve as the environment, quantities and yeast strains change. Strength also will change depending on feeding schedule.
To begin, you will need to create a levain, which is just mixed flour and water. This mixture is left to sit out, exposed to your environment, so the yeast and bacteria that are naturally present can attack the food found in flour. Over the course of several consecutive days, you will discard a portion, mix a new quantity of flour and water, and mix this new portion into the old one. By adding new flour and water into the mix, you are consistently giving the yeast present a new food source and encouraging them to multiply.
When it comes to flavor, a lot of people think that specifically comes from yeast – but this isn’t necessarily true, which can complicate your choice about which route to take.
Sourdough bakers are adamant that theirs is the only way to bake, and I applaud their stoicism. But great flavor can be made from commercial yeast as well. A lot of the flavor you find in dough comes from the acids developed during fermentation.
Sourdough tends to be stronger because it contains more Lactobacillus, one of the more prevalent microbes found during fermentation, which produces lactic acid and acetic acid. These two acids are the main flavor producers and are more highly concentrated in sourdough. You can coax both acids out in preferments or a final dough while using commercial yeast, but typically they will be at a lower level. Acids are where the flavors come in while yeast does the leavening or rising.
Just remember: If you are toggling between types of yeast – whether availability forces a pivot or you simply desire to try something new – quantities are not equal. The difference in hydration has a lot to do with it. You will need to use roughly three times as much fresh yeast as you would instant dry yeast. If changing from instant to active, you will need roughly 1.3 times more active dry yeast.
Your dough is a living, breathing thing, all because of the mighty power of yeast – a microscopic organism that is fighting for survival. If you learn to treat it well and learn its eccentricities, yeast will always repay you with fluffy doughs that turn into flavorful and aromatic pizzas.
LAURA MEYER is the owner of Pizzeria da Laura in Berkeley, California.
