Yeast: What is it & what kind should I use?


What Is it? What kind should I use?


You may have heard that there are three different categories of bread: quick breads, sourdough, and yeast breads.  “Quick breads” are cakes, cookies, and any baked product that uses a rising agent other than yeast such as whipped eggs, cream of tartar, baking soda or baking powder.  I will not really address sourdough here (which is where the yeast was originally “caught” and allowed to ferment, creating a highly nutritious and artisan bread).  Most of us start by baking yeast bread.  On this point there are many questions along the line of “what is yeast?”, “what is baker’s yeast?”, and finally…”active dry yeast or instant yeast?”  I hope I can clarify.


Chaya's Bread

What is Yeast?

It is a tiny single-cell fungus, and therefore a living thing.  Breads, alcohol, and vinegar require it.  Yes, even sourdoughs.  When people say “I don’t use yeast, I make sourdough” what they intend to say is actually, “I do not add dry yeast, I add sourdough starter.”  The reasons for doing so are plenty—the bacteria in sourdough starter have had plenty of time to start the pre-digestion of the sugars and enzymes that humans sometimes have problems digesting.  This means that the final product will be easier on the stomach.  Even now, many people purchase dehydrated sourdough starter which does resemble the store-bought stuff; it will not behave the same however.  All yeast breaks down the sugars, but the sourdough starter is given great lead-time to do the job more effectively through the fermentation process.

As yeast consumes the sugars, it releases carbon dioxide.  This released gas expands the dough and raises the baked product.  If you have ever used bad yeast (baking a doorstop), you know this all too well.

Although people often fare better on sourdough, yeast itself is a healthy food that has been consumed since the ancient Egyptians discovered how to isolate it (History of Yeast).  As with all things moderation is the key, but yeast within itself is considered to be rich in folate, thiamin, and many other vitamins and minerals (wolfram alpha). Keep in mind that there is not enough yeast in that loaf of bread to truly nourish you, but the vitamins are there just the same.

Baker’s Yeast


It is how it sounds; baker’s yeast is the yeast used in bread (as opposed to brewer’s yeast for alcoholic beverages, nutritional yeast which is an inactive flavoring and nutritional supplement, and so on).  The strand of fungus used for leavening bread products is generally the same strand most commonly used for brewing beer—meaning that there is little difference between “baker’s yeast” and “brewer’s yeast”, although they are not exactly interchangeable in your kitchen because they are processed differently. 


Types of Baker’s Yeast: Yeast Cakes, Active Dry, Instant

Cake of Yeast


Have you ever pulled out grandma’s cookbook to see “1 cake of yeast” written in a margin? Fresh yeast does come in cakes, but because the shelf life is so limited it is rarely considered by the home baker as an option.  The point of semi-dry or dry yeast is that it has a much longer shelf life than fresh yeast.  Remember, yeast is a living thing that needs to be fed.  If it is fresh and in some type of storage without sugars added to it, it will die of starvation.  It simply lies dormant in a dried state.

Once upon a time, there were vast differences in the performance of active dry yeast and instant yeast—not so much now.  Many see little difference in the effect by interchanging these ingredients in beloved recipes, although most bakers do have a favorite!

Active Dry Yeast

People do say that a reason to prefer instant yeast is that it can be added directly to the dry ingredients and does not need to be “proofed”.  I say, for as easy as it is to proof the yeast and determine its efficacy, it is a step worthy of five minutes.  In fact, I always proof my yeast whether I am using active dry or instant.  I treat the yeast the same and I get the same result (noticeably, anyway). 

Yeast Guide


My biggest advice to a new bread baker—do not get too caught up in all of the details of getting things perfectly, do not spend precious bread-baking time reading forum threads quarrelling through the “instant vs. active dry” debate.  Play around, see what works best for you, and above all else…

Enjoy your bread,




Side Note:  Many people enjoy using brewer’s yeast as a health supplement.  It is an active yeast, and any active yeast eaten (without baking first) will continue to grow inside the intestines and can deplete you of nutrients.  My recommendation? Get the vitamin B and other great nutrients available in the inactive nutritional yeast

Nutritional Yeast

It is delicious as a topping to popcorn, soups, and other dishes.  I highly recommend nutritional yeast, and you can find that here.




“History of Yeast” accessed 12/9/2012 at

“Nutritional Contents of Yeast” accessed through Wolfram Alpha.

The Cook’s Thesaurus, “Yeast” accessed 12/9/2012 at



Nothing in this blog constitutes medical advice.  You should consult your own physician before making any dietary changes.  Statements in this blog may or may not be congruent with current USDA or FDA guidance.



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