For the best results in a yeast-raised dough, it pays to understand what a recipe means when it calls for a specific type of yeast, and what the implications may be for using a different kind.

Dry yeast is one of the miracles of modern baking—a free-flowing granular powder made from millions upon millions of dehydrated single-celled organisms. Once hydrated, these li'l critters munch on the sugar or starch in a dough, producing the alcohol and carbon dioxide that give bread its distinctly fermented flavor and airy rise.

Successfully resurrecting dry yeast depends entirely on how it was processed, so when a recipe calls for a certain type, the directions will be tailored to its specific needs. Those directions may kill a different type of dry yeast outright, or fail to provide the conditions needed for it to thrive, resulting in poorly risen doughs—or doughs that don't rise at all.

That means it's vital for bakers to understand the language used to describe various types of dry yeast, and to realize that blind substitution is a crapshoot at best. Some recipes, particularly high-moisture doughs with a short proofing period, can provide a hospitable environment for many types of yeast, creating a false sense of security around substitution. In the realm of low-moisture doughs with a cold, overnight rise (think bagels, English muffins, or cinnamon rolls), the wrong type of yeast can spell certain death for bread. For the best results in a yeast-raised dough, it pays to understand what a recipe means when it calls for a specific type of yeast, and what the implications may be when you use a different kind.

A Quick Primer

Dry yeast comes in two forms: active and instant. "Active" describes any dry yeast that needs to be activated prior to use, while "instant dry yeast" describes any dry yeast that's ready for use the instant you open the package. Instant yeast is an ingredient of its own, as well as a category that can include specialized products, like RapidRise or bread machine yeast. It sounds confusing at first, but just think of a product like yogurt—a distinct ingredient that also includes specialties like Greek yogurt, flavored yogurt, or even frozen yogurt.

Because the language used to describe yeast is not regulated, brands are free to employ these terms however they like, leading to a great deal of confusion for consumers and professionals alike. After five years of active recipe development for my cookbook, , and two years of daily feedback from readers on Serious Eats, I've seen crystal-clear patterns of success and failure, which I've used to develop my own "best practices" for each type of dry yeast.

This information may contradict what you've read elsewhere (again, the terms are wholly subjective), but it's a road-tested guide that will help bakers avoid trouble in yeast-raised doughs.

Active Dry Yeast

As the name suggests, active dry yeast must be "activated" by dissolving the granules in warm water, according to the package directions. (The specifics can vary from brand to brand; some may call for sugar to be added as a fuel for the yeast.)

If the yeast is still alive, it will begin to foam and grow within a few minutes.

Active dry yeast is so unstable that any given packet may well be dead, so it's important to verify whether or not it's alive before proceeding with the recipe—even if the yeast hasn't yet reached the expiration date printed on the package. Active dry yeast also has a comparatively large grain size, further necessitating direct contact with warm water to dissolve. Due to this time-consuming step, as well as the high risk and cost of failure, active dry yeast is rarely used in a professional setting.

The Basics

Active dry yeast is highly perishable; always check the expiration date before use.

Potency can vary over time, producing inconsistent results

Must be rehydrated before use

Easily damaged by liquids above 115°F (46°C)

Suitable for recipes that require more than one rise

Suitable for cold-proofed doughs

To use in place of instant yeast, activate according to package directions, using a portion of milk or water from the recipe rather than additional liquids.

Instant Dry Yeast

Thanks to its unique manufacturing process, instant yeast is guaranteed to be 100% active, so it's ready for use straight from the package, and its behavior is consistent over time. Due to its small grain size, instant yeast will readily dissolve in the ambient moisture of a dough, eliminating the need for rehydration. Given its stability and shelf life, instant yeast is safe to buy in bulk, dramatically lowering its cost compared with the tiny packets of active dry yeast sold in stores.

The Basics

Extremely stable; can be frozen for several years

Consistent behavior over time

Tolerant of temperatures up to 130°F (54°C)

Suitable for recipes that require more than one rise

Suitable for cold-proofed doughs

My favorite brands: SAF Red Label, Dr. Oetker

To use in place of active dry, incorporate directly into the dry ingredients. Add any ingredients used for proofing (warm water, sugar) to the dough along with other liquid ingredients.

Fast-Acting Instant Yeast

As a subcategory of instant yeast, fast-acting yeasts are likewise stable and easy to use, but formulated to operate on an accelerated timetable, making them unsuitable for recipes that require a long rise. Whether you're using RapidRise (from the Fleischmann's brand) or Quick-Rise (from Red Star), it's important to remember that these yeasts are defined by their trademark rather than by some objective measure, so their behaviors can vary wildly.

The Basics

Highly stable; can be refrigerated up to one year

Consistent behavior over time

Tolerant of temperatures up to 130°F (54°C)

Designed to work with only one rise

Not suitable for refrigerated doughs

Not suitable for doughs with a long, slow rise

To use in place of instant dry yeast, proof at cool room temperature, and follow the recipe's visual cues (such as letting the dough double in bulk) rather than a specific timetable. To use in place of active dry yeast, incorporate directly into the dry ingredients. Add any ingredients used for proofing (warm water, sugar) to the dough along with other liquid ingredients.

Bread Machine Yeast

Like other types of instant yeast, bread machine yeast doesn't need to be dissolved before use and keeps well in the fridge or freezer. As its name implies, this style is designed for use with a bread machine and works best under those specific conditions. It can be used with reasonable success in recipes that call for instant yeast, though it will not produce as vigorous a rise in refrigerated doughs.

The Basics

Highly stable; can be refrigerated up to one year

Consistent behavior over time

Tolerant of temperatures up to 130°F (54°C)

Designed for use in recipes formulated for bread machines

Not as energetic in refrigerated doughs

Experienced bakers can successfully substitute one type of yeast for another with a few tweaks, hydrating active dry for use in a recipe that calls for instant, or using RapidRise to shorten the proofing period of a slow-fermented dough. But for beginners, the best course of action is to find the right yeast for the job, knowing that not all types of dry yeast can be used interchangeably or produce equally good results on a 1:1 basis. Given its shelf life, stability, and versatility, plain instant yeast, such as SAF, is my go-to recommendation for baking at home, and it's what I call for in my cookbook and here on Serious Eats.

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