All right, folks, let’s talk yeast. In case you hadn't heard, baking has become our new national pastime—or maybe it's been yours all along—and it's led to an onslaught of questions about yeast. Like, what does one do if there's only one kind of yeast at your store and it's not the kind you need? Or worse—what if there's no yeast of any kind to be found at all? Is your recipe doomed? And, for those lucky enough to encounter a fully-stocked shop—what's the difference between all these different types of yeast?
We're prepped to answer all those questions, but first:
Yeasts are single-celled microorganisms that predate humans by...hundreds of millions of years. There are more than 1,500 species of yeast, but the species we're concerned with today is saccharomyces cerevisiae, derived from Latinized Greek meaning "sugar-fungus." This group of yeasts includes strains of baker's yeast and brewer's yeast, responsible for producing our favorite carb-heavy treats: bread and alcohol. They work by feeding on sugars and converting that food into carbon dioxide (and alcohol, given enough time), giving your baked goods that soft, airy structure you love and your beer that bubbly nature.
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There are three main types of commercially produced baker's yeast: active dry, instant, and fresh. All of them will work to leaven doughs in any given yeasted baking recipe, but each has slightly different properties, and, for the more discerning palate, varying flavors.
Live yeast is partially dehydrated, rendered inert, and ground into granules. You'll often find this sold in ¼-oz. packets or a 4-oz. tinted glass jar in the baking aisle. These dormant yeast cells can be stored at room temperature for several months until their expiration date but are heat-sensitive and potency can vary. Be sure to store it away from super warm areas up until the moment you're ready to bake—active dry yeast will begin to die once exposed to temperatures higher than 120°F. To extend shelf life, store sealed packets in an airtight bag in the freezer to keep the yeast in a more secure state of suspension.
Before being added to your recipe, active dry yeast should be dissolved in lukewarm (between 100°F and 110°F) water or milk, to ensure its activity level. If your yeast mixture does not increase in size and become foamy in 10 to 20 minutes, your packet was likely DOA and no longer viable. This likelihood is not unthinkable: The manufacturing process for active dry yeast can kill up to 25% of yeast cells.
Active dry yeast has a longer fermentation process when compared to other yeasts, meaning it is best suited for dough recipes that call for a double rise and a longer proofing time.
Also known as "bread machine yeast" and "RapidRise," instant yeast is more shelf-stable and tends to be more reliably and consistently active than active dry yeast (talk about misleading names!). The most popular brand of instant yeast among pro-bakers is SAF-Instant, which is sold in a 16-oz. package. Instant yeast has finer, smaller grains than active dry yeast. This increased surface area allows for a faster rehydration process, and it can be used in recipes without blooming the yeast in a liquid beforehand. (Nonetheless, I still prefer to bloom instant yeast to ensure even distribution in the dough.)
When used in substitution, ¾ teaspoon of instant yeast is equivalent to 1 teaspoon of active dry due to its increased potency and shorter fermentation time. Instant yeast can be stored in the freezer in an airtight container for up to 2 years.
Also known as "cake yeast" and "compressed yeast," fresh yeast comes in big blocks or smaller, individually packaged cubes and can be found in the refrigerated aisle near dairy and eggs. It is the only form of commercial yeast that isn't dehydrated: a solid but crumbly concoction of water and yeast, its rubbery texture is halfway between paste and modeling clay. Due to its high moisture content, this form of yeast is the least shelf-stable, requiring refrigeration and lasting only about two weeks under ideal conditions. If kept in too humid or unclean a container, white tufts of mold can develop within a week and the yeast is no longer safe to use. For longer storage, divide your fresh yeast into individual portions and wrap each piece tightly with plastic wrap before placing in your freezer for up to a year.
Some bakers prefer to use fresh yeast in sweeter recipes, such as donuts, for its more vibrantly yeasty perfume. When used in substitution, 1 oz. of fresh yeast is equivalent to 0.4 oz. of active dry yeast or 0.33 oz. of instant yeast. To substitute for a ¼-oz. packet of active dry yeast, use about ⅔ oz. of cake yeast. To substitute for a ¼-oz. packet of instant yeast, use about ¾ oz. of cake yeast.
Yeast is yeast at the end of the day, and they all work in a similar pattern—brewer's yeast will rise your bread, but it does also have a more bitter flavor that can be undesirable in a traditionally sweet baked good. So, you know, enter at your own risk.
Nutritional yeast is also derived from saccharomyces cerevisiae, but it undergoes a "deactivation" process during which the live yeast cultures are killed by heat. Because the yeast is essentially dead, it can no longer provide leavening magic to your baked goods. It is, however, a delicious seasoning that can provide a salty, cheesy, nutty kick to anything savory you're cooking up: popcorn, vegan mac and cheese, roasted veggies, fried rice—the list goes on!
I often call sourdough starters "DIY yeast"—they're all the rage now, and I wholeheartedly love them. Starters are a combination of yeast and good bacteria (lactobacillus) that any home cook can cultivate: Simply let a mixture of flour and water sit together until it ferments, and you’ve got yourself some DIY yeast! Yeast and bacterial spores naturally occur in flours, so depending on the type of flour you use, the ratio of water you feed into it, and variables in the surrounding environment (temperature, air flow), each starter will be a slightly different mix of microorganisms. Because starters are born out of naturally occurring yeasts, they contain different species of yeasts than what's found in baker's yeast. For example, saccharomyces exiguus is a wild yeast that can be found on various grains and plants—even in the air, floating by around us.
Sourdough starters often take a longer time to leaven a recipe when compared with the speed of commercial yeast and will also give your final baked good a different flavor profile: more sour, less sweet, and perhaps an earthier, artisanal je ne sais quoi. Starters can make a nice rustic loaf of sourdough bread, but they can also be used in a myriad of applications beyond just bread: pancakes, crackers, donuts, even cookies!
Baking soda, when used alongside an acidic ingredient—such as lemon juice, vinegar, buttermilk, or brown sugar—will also produce carbon dioxide and can be an effective leavener in baked goods like cakes and cookies. Baking powder, being part baking soda (an alkaline substance) and part cream of tartar (an acidic substance), will undergo similar chemical reactions that produce carbon dioxide: once when it comes into contact with a liquid, and, if it's a double-acting baking powder, a second time when it is heated during the baking process.
While both baking soda and baking powder can help to leaven certain baked goods, neither has the strong lifting power of baker's yeast and both can leave a bitter, soapy aftertaste when used in large amounts. To avoid that unpleasant taste, keep to a maximum of ½ teaspoon of baking soda or 1 ¼ teaspoon of baking powder per cup of flour in any given recipe. If you're inkling to bake something and only have baking soda or baking powder on hand, quick breads and soda breads are great alternatives.
June Xie
Senior Food Producer
June Xie is the current Senior Food Producer for Delish, where she hosts recipe videos and the wildly popular YouTube show, Budget Eats. She previously worked in numerous restaurant kitchens throughout NYC before first joining Delish as our Test Kitchen Assistant and chief baking expert with a passion for bread dough, peanut butter, whipped cream, and gluten free cookies. She also loves staring at alpacas.
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