Hello! I'm Alissa, a classically trained chef who is passionate about teaching people how to cook through methods, techniques and basic science principles. I currently live in San Diego, California with my husband, Steve, and sweet dog, Nina. I love learning about food, eating good food, and cooking good food for my loved ones.

All About Yeast

Yeast is a magical ingredient. It’s what gives bread its characteristic lightness and airiness. It can be cultivated naturally or used in its most common man made form. In this post I will teach you what yeast is, where is comes from and the different types of yeast most commonly used.

What is yeast?

Yeast is a single celled organism that is found everywhere there is natural plant matter, in the air, soil, on plants, in flour etc… Technically, yeast is a fungi.

In baking it functions as a leavening agent. A leavening agent is something that produces gas or air to lighten a food and give it a light airy texture.

Yeast loves warmth, moisture and feeds on sugar, which can be actual sugar or the natural sugar found in the starch in flour. When yeast has these these needs met, it eats the sugar and produces alcohol and carbon dioxide as a byproduct. This process is also called fermentation. All alcohols are made from yeast and the fermentation process. The carbon dioxide byproduct is what fills bread with air and the gluten structure made from kneading bread traps all that air resulting in the beautiful pillowy texture that is bread.

Fascinating!

How is yeast made?

Manufactured yeast is made by cultivating specific strains of yeast. Manufacturers will find specific strains of yeast that they like the characteristics of. Once they find those strains they use a molasses and water mixture to cultivate more yeast. The sugar from the molasses allows the yeast to multiply and provides it with plenty of food. Once enough yeast has been cultivated the mixture is strained and the alcohol is removed. The yeast liquid is called cream yeast which is then dried to create the little pellets we can buy today.

Types of yeast

There are 5 major types of baking yeast. Natural yeast, fresh yeast (also called wet, cake or compressed yeast), active dry yeast, instant yeast, and rapid rise yeast. The easiest yeast to come by in any grocery store is active dry yeast and rapid rise yeast or quick rise yeast. There is also yeast specifically for bread machines that really can only withstand one rise.

Natural Yeast

Natural yeast is what is found naturally in flour and the air. Natural yeast is cultivated when making a starter. There are many methods to make you own starter but it always starts by mixing water and flour. This mixture is then left to sit to allow the yeast to feed on the flour and start the fermentation process. The starter is fed periodically with fresh flour and water to keep it alive and cultivate even more natural yeast.

Natural yeast and starters are much harder to control. There are a lot of factors that go into the characteristics of the starter. The type of flour you use, water type, water amount, feeding times, all go into the final flavor profile and strength of the starter. It’s one of those things in the culinary world that chefs love to brag about. They brag about how long they’ve kept their starter alive.

There are many guides out there on how to make your own starter. This one by King Arthur in particular is great because they have really simple, easy to read, step-by-step instructions. And plenty of recipes to use up your starter once it’s established.

Click here to view on kingarthurbaking.com

On a side note, if you are going to make your own starter, I highly recommend getting a scale. It is the most accurate way to measure flour. When making a starter you are often discarding a certain amount of starter and then adding very specific amounts of flour and water. A scale makes the whole process a million times easier. It really doesn’t need to be fancy but go with a reliable brand. I recommend this one.

Wet Yeast

Also called fresh yeast, comes in a little brick. It has moisture in it and should be crumbled into the water in your recipe before using. Some people swear by fresh yeast saying that is produces a better tasting end product. While I haven’t had much experience with fresh yeast I would argue that it doesn’t really matter…

Fresh yeast is hard to come by. A lot of restaurants and bakeries will sell this to customers. Just ask your favorite bakery and if they don’t have it, ask if they know of any bakeries that do. I worked at a bakery that sold it back in Provo (Provo Bakery for my Utah readers, if you are interested). You can also check specialty grocery stores or look online.

My biggest gripe with fresh yeast is that it is very perishable because of its moisture content. In the fridge fresh yeast will only last two weeks at best. The other major problem with fresh yeast is finding a reliable source to buy it. You never know how long they have been storing it. To me it just isn’t worth the hassle.

Active Dry Yeast

Active dry yeast needs to be activated by water first before mixing. The size grains of yeast are a little bigger in this state and need a chance to dissolve first or they won’t properly mix into the bread you are making. If you don’t activate it in water first you will still see little grains of yeast in your bread.

Interesting thing I learned from my research, yeast undergoes a heating process when drying and active dry yeast is heated higher than other yeasts. Because of this process, 25% of the yeast is killed off. So that means that active dry yeast you buy at home could be partially dead on arrival or fully dead to begin with! Fascinating! So it’s always good to check your active dry yeast first by dissolving it in some warm water with a little bit of sugar to make sure it is alive and well.

(As I write some blog posts, I find out so much information I didn’t know or don’t really trust. This idea that active dry yeast can be so unreliable is interesting to me because active dry yeast is the most easy to come by. It is hard to find a grocery store that doesn’t carry active dry yeast. So is active dry yeast isn’t reliable and instant yeast is, why isn’t instant yeast easier to find? Especially in a bulk package? Instant yeast is so much better! There is so much to learn to understand. Haha a little insight into how my mind works…)

Instant Yeast

Instant yeast comes in a much finer grained than active dry. Because of this you can add instant yeast right in with all your ingredients without having to activate it first.

This is the yeast I use to bake with and is the yeast most professional kitchens and bakeries will use as well because of how easy it is to use and for how reliable it is. Instant yeast is alive 100% of the time. The drying process to make instant yeast is much more gentle than for active dry yeast. So it will always work fresh from the bag. That being said, it never hurts to test your yeast just to be sure.

In my research I also came across an interesting fact, because active dry yeast can come DOA, it also has a stronger smell and taste than instant yeast. Another reason I love Instant yeast is its clean taste and smell.

Rapid Rise Yeast

Also called Quick Rise yeast. I’ll be honest I am a little confused by what kind of yeast this actually is. From my understanding these types of yeast are either meant for a bread machine or are only good for one rise. But they are also marketed as instant yeast.

From what I’ve read, this type of yeast has additives in it to make it rise more quickly, essentially give it a boost.

An Experiment

Because of my confusion on RapidRise yeast, I did a little experiment at home to try out different types of yeast. I used a really basic white bread recipe from one of my favorite cookbooks Baking by James Peterson.

Click here to view on Amazon

I made four half recipes of his sandwich bread (straight dough) recipe using a different type of yeast for each. I used Fleischmann’s Active Dry yeast, Fleischmann’s RapidRise yeast, Red Star’s Quick Rise yeast, and Saf-Instant yeast.

This recipe has two rises, one rise right after mixing and then another once the bread is shaped before it is baked. And honestly they all turned out the same. I did notice that the RapidRise and Quick Rise yeast were a little faster than the active dry yeast and the Saf-instant yeast. But they all rose about the same, had no problems with two rises and tasted the same in the end.

That being said, I cannot vouch for RapidRise and Quick Rise in a longer proofing time. I don’t know how they would do with a bread that rises overnight. Maybe that will be my next experiment.

My conclusion: My absolute favorite yeast to use is Saf-Instant. So that is my recommendation first and foremost. That being said, I know that at most grocery stores you will find active dry, RapidRise and Quick Rise yeast and not Saf-Instant. This experiment showed me that they all work for a simple quick rising bread. But if you want a reliable yeast that you can use for all types of bread use Saf-Instant.

Click here to buy on kingarthurbaking.com

Not an affiliate link. I just want to provide a reliable source to buy yeast. Because of the perishable quality of yeast, I wouldn’t buy yeast on Amazon, I just don’t trust it.

Storing Yeast

Yeast will last in an airtight container in the fridge for 3-4 months and in the freezer for much longer. The yeast I use has been in my freezer for at least a year is still alive and well.

My favorite container to freeze yeast in is in an OXO POP container. It is an airtight container that keeps yeast nice a fresh. I use the 1 quart square container. I love these things. (They are also perfect for storing brown sugar.)

Click here to view on Amazon

Testing Yeast

It’s best to test your yeast every once in a while to make sure it’s still alive and will function how it needs to. I found a great tutorial here.

To do the test:

  1. Fill a liquid measuring cup with 1/2 cup water 110°-115°F. The water should feel warm. But I recommend getting a thermometer. It takes all the guesswork out of it. (This is my favorite thermometer.)
  2. Add 1 tsp granulated sugar and stir to dissolve.
  3. Add 2 1/4 tsp yeast (or one packet of yeast) and stir just to combine.
  4. Wait. Your yeast should bubble up to the 1 cup mark on your measuring cup within 10 minutes. If it doesn’t then it is time to buy new yeast.
A cool little time-lapse I did of the test I did on my yeast. So cool!

Substituting Yeast

For most recipes, substitution of yeast is going to occur between active dry yeast and instant yeast. Active dry yeast is going to take a little bit longer than instant yeast. So you need less instant yeast than active dry. The substitution is 1 tsp active dry=3/4 tsp instant yeast. Other than the adjusted amounts they can used interchangeably.

Just remember active dry yeast needs to be activated. So use whatever liquid is needed in the recipe to dissolve active dry yeast. Instant yeast does not need to be dissolved first. So it can be added with everything else.

Other Properties of Yeast

Other Ingredients Inhibit Yeast

Other ingredients added to bread like salt, fat, and eggs inhibit yeast growth. There is just more in the way of yeast eating the sugar from the flour. So you might notice that an enriched bread like challah or brioche rise a lot slower and not as much as a plain bread dough like a basic white bread. It’s not your yeast, there is just more going on in the dough.

Granulated Sugar is like Fast Food to Yeast

Yeast loves sugar. It’s what it eats. Sugar can be found naturally in the starches of flours but granulated sugar is often added to bread recipes to help with flavor and caramelization. If you bread recipe calls for granulated sugar you might notice that it rises faster than bread without sugar. Sugar is like fast food to yeast. It is instant food and energy.

Yeast Needs a Temperature that is Just Right

Yeast thrives in an environment around 70°-90°F. Which is just about room temperature. A lot of recipes use warm water around 90°-110°F which which once mixed into your dough, the dough temperature will be around 70°-90°F. Yeast will die at too high a temperature. I would not use water above 115°F to stay on the safe side. But most yeast will die at 140°F. Again, get a thermometer. It is a game changer!

The Faster the Rise the Less Flavor Produced

With a lot of recipes you can adjust the yeast amount. The more yeast you add the less time bread will take to rise but the more you will be able to taste the yeast and nothing else, the less yeast you add the more time bread will take to rise but the more flavorful your bread will be naturally.

A slow rise makes for a more flavorful loaf. The best way to know what that actually tastes like is to experiment with two different bread recipes one with a short rise time and one with a long, potentially overnight rise. Just know that faster doesn’t always mean better.


Whew. That was a long one. And there is so much more to yeast! I love having this blog because I learn so much! And it makes me question the things I was taught and what is out there on the Internet. I hope you learned something too! As always, let me know if you have any questions. I would love to hear from you!

*This post contains affiliate links. If you use these links to buy something I may earn a commission at no extra cost to you. I only recommend products I would use myself and all opinions expressed here are my own*

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