Well hello, Fermentation Nation! Let’s talk about the star of this show: yeast. Every leavened bread needs yeast in order to rise, and a basic understanding of this microorganism—its power, its limitations—can take your bread from ok to awesome. Although, let’s be honest, most people will think you’re a wizard if you make bread. Moral of the story: make bread, people will love you even more. Second moral of the story: read on to learn more about fermentation, different types of yeast, and some general guidelines for proper yeast usage.
Let’s be real right now, fermentation is magic. Science magic, but magic all the same. You throw a bunch of tiny microorganisms together with some otherwise unexciting ingredients and you get bread, kombucha, beer, wine, yogurt, kimchi, pickles…so many things, guys. In bread’s case, successful fermentation results in well-risen, tasty bread. Once you mix together your wet and dry ingredients, the starch molecules in your flour that were damaged during milling begin to break down with the help of some well-placed enzymes, and those starches release their natural sugars, glucose and fructose (and sometimes maltose). The enzyme of which I speak, amylase, is usually added to flours. If you use a sourdough starter as your leavener, the wild bacteria lactobacilli can take care of those pesky, hidden sugars.
The yeast in your dough chows down on the glucose before proceeding to burp out tiny amounts of carbon dioxide and ethyl alcohol. The carbon dioxide quickly finds itself trapped in air pockets that you’ve introduced to your dough through your kneading/folding, and those awesome gluten bonds you’ve helped develop keep those expanding bubbles from bursting. The alcohol produced, so cherished by breweries, contributes to flavor and makes your dough smell kinda like beer. In the end, however, the CO2 and alcohol bake off, leaving you with a delicious, non-alcoholic loaf of bread.
Which Yeast to Use?
There are four forms of leavener available to home bakers: fresh yeast, wild yeast, active dry yeast, instant yeast. Not all are created equal. I’m looking at you, fresh yeast. While fresh yeast, which comes in blocks or “cakes”, is technically an option, you won’t have an easy time of finding it, its shelf life is about 2-3 weeks, and only about 30% of that block is yeast. So maybe skip the fresh yeast.
If you want to use wild yeast, you’ll need to get your hands on some sourdough starter. Check out my page on Gloria the Sourdough Starter for more info on cultivating and maintaining a wild yeast culture.
I think about Active Dry Yeast like the wizened elder of commercial yeast, having debuted around the start of World War I. Active Dry was a star in its day, revolutionizing the storage of yeast and upping its tolerance for being shipped around the world. Active dry yeast requires proofing, which entails stirring the granules of yeast along with some sugar into warm water and waiting until the top gets foamy. This extra step, while admittedly not requiring much time or effort, feels more nostalgic than appealing, like paying for cable. Why do it, there’s a better way.
Instant Yeast is the streaming service in this metaphor. You do not need to proof instant yeast; just add it to your flour and you’re good to go. Instant yeast granules are smaller than active dry granules, and instant yeast goes through a gentler production process, leaving you with more readily activated yeast and a lower percentage of dead yeast cells. Most recipes call for instant yeast now as well. I suggest keeping some instant yeast around if you have to choose one.
Assorted Yeast Trivia
1. There is such a thing as too much yeast
Dumping in a bunch of yeast and watching your bread rise to monumental heights would be nifty; alas, this utopia can never be. Flour can only provide a certain amount of sugars, and once that food supply is gone, it’s gone. The dough with too much yeast rises fastest, true, but you know what they say about that tortoise and that hare in that race that one time. A faster rise not only means less awesome flavor in the finished loaf, but a premature exhaustion of sugar results in off tastes that come from an overabundance of alcohol. At the same time, this alcohol weakens your precious gluten bonds. If you add more yeast than absolutely necessary, you may find yourself with a collapsed, yucky tasting loaf. So just don’t do it.
Least yeast is beast yeast. That started out as a kinda stupid rhyme, but actually, if you use as little yeast as possible, you end up with stronger dough. Don’t cut the yeast entirely, of course, and keep in mind that less yeast will equal longer rising times, but hey, “low and slow” could be a great bread baker’s maxim.
2. Yeast will sleep in the cold and not-damp
You want your yeast to stay asleep until the last possible second—when you add it to your dough. You’ll find active dry and instant yeast on the baking aisle in your grocery store, but once opened, store your yeast in an airtight container in the fridge. If you rarely make bread, the three-packet, Wonka-Fun-Dip-like option might be your best bet, although I suggest dumping all the contents into one small container because most recipes call for yeast in quantities different from what each packet contains. If you bake more regularly, instant yeast comes in small, glass jars, too. If you’re super ambitious, you can also find 1 pound packages which you’ll need to put in a sealable jar of some sort.
3. Until the mid-1800s, yeast enjoyed almost divinity-level admiration
Louis Pasteur gets a lot of the credit for “discovering” fermentation, but people before him had actually already done a lot of that. In any case, yeast was too small for people to see with their own human eyes, so nobody quite knew why there was this frothy stuff making their bread rise or making their drinks bubbly and alcoholic. They liked the results enough to give it the benefit of the doubt though. So, thank you, people from a long time ago who decided to eat and drink the weird, inexplicably bubbly things.
The Bread Baker’s Apprentice by Peter Reinhart
I’m Just Here for More Food by Alton Brown