Understanding Yeast...Varieties of yeast

Understanding Yeast…What is Yeast…Varieties of Yeast


Homemade breads are so much in.

You also decide to bake one for your family. Fully geared up, browse through internet. So many eye-catching pics of breads, so many easy recipes. After lot of comparisons, reading, struggling everything, you finally make up your mind on one recipe. But, what this ‘one packet yeast’ means? What is instant yeast? What is active dry yeast? Are they different ? Or just different names of the same thing ? One recipe says proof yeast other doesn’t… Why so? And what does proofing means?

Friends, this is my story. Around 10 years back, when I decided to try my first bread, many such questions popped up in my mind.

I am sure, you too must have faced such questions…. if not all at least some, Right?

So, let us try to understand this complex yeast. Understanding of yeast is very important. Once you have mastered that, half the battle is won.

Yeast, as you all know is the backbone of bread. No yeast means no bread. However, now we too have sourdough breads, but still as of now, yeast breads capture the markets as well our homes.

As you all know through my earlier article that there are three main leavening agents— Baking Soda, Baking Powder and Yeast. The first two we have already discussed in the post titled Difference Between Baking Soda and Baking Powder. Now let us discuss yeast.

It is a long write up. Please read it slowly and if need be more than once.

What is Yeast ?

Yeast is a single celled microorganism related to mushrooms. Out of more than 1500 species of yeast, just one, Saccharomyces cerevisiae  (which means sugar eating fungi), is used in the kitchen. Other than baking breads, the same species of yeast is also used for brewing beer, making wine and other food products such as soy sauce and vinegar. It is called both Baker’s yeast as well Brewer’s yeast.

Being a leavening agent, the function of yeast is to convert fermentable sugars present in the dough into carbon dioxide and ethanol. The carbon dioxide thus produced helps the bread rise.

Yeast does this by feeding on the sugars in the flour and expelling carbon dioxide in the process. This gas with no place to go but up, fills the dough with thousands of balloon like bubbles. Once the bread is baked, these bubbles give the loaf its airy texture.

Yeast  dough  rise once, then punched down, then rise again and finally go into the oven. In the oven, heat rouses the yeast to one last great expulsion of carbon dioxide before they reach 140 degrees Fahrenheit and die.

Yeast contributes flavor as well. Hence, adding more yeast to a recipe won’t cause bread to rise more but will produce a more intense yeast flavor.

Types of Yeast

Baker’s yeast is available in various forms, which differ mostly by the content of moisture in it.  There are mainly two types of yeast, fresh yeast and dry yeast. However, dry yeast is further categorized into active dry yeast, Instant yeast and rapid rise yeast.  We will see how they are different from each other but before that let us see what these terms mean.

Fresh Yeast

Fresh yeast is also known as Cake yeast or Compressed yeast. It is called cake yeast only because it is sold in the form of tiny cakes. You get these in the refrigerated section of bakery shops or supermarkets.  It is made from a slurry of yeast and water with enough of its moisture  removed so that it can be compressed into blocks.

It needs no proofing and can be added directly to the flour or dissolved with water first. Dissolving in water helps it to disperse fully.

Despite the fact that it leavens beautifully and gives a slightly sweet flavour to the baked goods, it  is not at all advisable for home baking. It is highly perishable and used only by professionals. Lasts only for about 2 weeks even if refrigerated.

Once I also bought it but had to throw it as couldn’t use it fully. Also it was difficult to use in terms of measuring it as it was very sticky. It is measured in grams and measuring 3-4 grams was not easy. So please don’t be tempted to buy it at any cost unless you plan to do it commercially.

If the recipe calls for Fresh yeast and you have active dry yeast or instant yeast then you can easily interchange these by making certain changes in the measurements.


Active Dry Yeast

It is a dry granular yeast.  These are granules of live yeast cells wrapped in dry dead cells. Thus, it is an active yeast but remains dormant until it comes into contact with liquid.

Before working with active dry yeast, it must be activated or proofed by dissolving it in warm water. The resulting foam is confirmation that the yeast is still alive…

Active Dry yeast has a long shelf life. If not opened, remains good for one year even at room temperature. Once opened, remains good for 6 months in the refrigerator and even up to a year if kept in the freezer. If kept in the freezer, then you can use directly without thawing it.

1 Package Active Dry Yeast = 2.25 tsp or 7 gms or 0.25 ounce


 Instant Yeast

It is also granular yeast but its granules are much smaller than that of Active Dry Yeast. It has very high percentage of live cells. It is ground much finely and thus absorbs moisture faster, rapidly converting starch and sugar into carbon dioxide.

It can be added directly to the flour. It  doesn’t  require to be proofed by dissolving in warm water. However, still some people proof it by adding it in warm water just to ensure that the yeast is active and not expired.

At times a very small amount of ascorbic  acid is added to the instant yeast to preserve it. Due to this it can be preserved for almost a year at room temperature.



To summarize, Fresh Yeast, Active dry yeast and Instant yeast are more or less same except the following two differences :

  • Moisture content and hence the physical looks (appearance).
  • Active dry yeast needs to be proofed or bloomed in warm water before adding to the flour, whereas, Fresh yeast and instant yeast are added directly to the flour.

They all follow the same principle of  dough  rising  once, then punched down, then rise again and finally go into the oven.

These can be used interchangeably, with variation in measurements.

Conversion Chart

Instant yeast is used less in quantity as compared to Active dry yeast.

So, multiply the quantity of Active  Dry yeast by 0.75 to convert it into instant yeast.

And, multiply the quantity of Instant Yeast by 1.25 to convert it into Active Dry Yeast.

Or, in more simple words,

1 tsp Active Dry Yeast   =  3/4 tsp Instant Yeast

1 tsp Instant Yeast   =  1.25  tsp Active dry Yeast.

8.5 Grams Fresh Yeast = 1 tsp Instant Yeast

5.7 Grams Fresh Yeast = 1 tsp Active Dry Yeast

Rapid Rise Yeast

Rapid rise yeast is a type of instant yeast only but has even more fine granules. Since the granules are very small they dissolve easily  and rise quickly and hence the name given rapid rise to it.

But very quick rising affect the taste of bread adversely.  Breads made with rapid rise yeast do not have as much flavor as the breads made with other yeasts.

It is also called bread maker’s yeast or bread machine yeast.

No doubt it saves lot of time. If using Instant yeast then bread recipe requires only one rise. First rise is replaced by 10 minutes rest and you don’t have to punch the dough afterwards. Thereafter the dough is shaped into loaf/donuts etc and left for the second rise.

Rapid rise yeast cannot be interchanged with any other yeast. So, if the recipe calls for rapid rise yeast then use it that only.

How much Yeast to Use

Lower the amount of yeast, more is the rising time hence more flavor in the bread.

The exact amount of yeast needed to rise bread dough depends on three things:

The type of yeast used – As discussed above.

The temperature of the dough – Whether hot or cold, it is advised not to use much yeast. It will rise slowly taking a long time in winters whereas in summers it will take less time. This is because a higher temperature makes the yeast more active.

The length of rising time. The slower the rise, the less yeast you need.  The rising time can be controlled  by varying the amount of yeast and the temperature of the rise. For example, a recipe may call for 2 teaspoons of yeast and 2 hours of rising, but if you’re going to be out for the day, you can reduce the amount of yeast to ½teaspoon, rise the dough in the refrigerator overnight, and finish the bread the next day. The lower temperature and longer rising time will allow the yeast to multiply more gradually and create a more complex flavor.


You took utmost care in everything yet your bread didn’t rise. Why?

Look for the possible reasons…

Expired Yeast – While using active dry yeast,  it is first  bloomed/activated in warm water, making it clear whether the yeast is good or not. But in the case of instant yeast it is difficult to make out. This is the reason that though not required but still  some people activate in warm water before using it. If the yeast is active, it will produce a bubbly mass within 10 minutes. If doesn’t then the yeast is not good enough, so better put it in the bin and buy a new packet of yeast. Always buy good quality yeast.

Temperature of water – Yeast needs just warm water to activate. Ideal temperature of water for proofing yeast is 105 degrees Fahrenheit. It simply means warm water in which you can dip your finger comfortably for few seconds. Hotter than this will kill yeast and if cooler than yeast will not activate fully.

Salt – Salt is a yeast inhibitor and it is best to add it so it is not touching the yeast. It’s better to use non iodized salt, because iodine attacks yeast activity. Remember reading Kosher salt in recipes? Kosher salt is basically without iodine salt.

Dough not punched down – After the first rise, the dough is punched down or knocked down. This simply means to deflate the dough, shape it and leave it for second rise. If the dough is not deflated properly then alcohol built up during the first rise doesn’t get released and creates a toxic environment that kills the yeast. So always punch down the dough properly.


Can Baking Soda / Powder be interchanged with Yeast?

The short answer is “No” for the simple reason that both of them work in fundamentally different ways and should not be used as a substitute for each other.

Recipes that use Baking soda / powder rely on a chemical reaction for their rising properties. They react with acid/liquid and heat to create gases and create the rising action. To aid this process many times we add lemon juice or buttermilk to the recipe, to support the rising action. The dishes need not be pre- prepared. And rising takes place during baking only.

Whereas, in the case of yeast, the dough need to be allowed to “rise” before baking. In the process they act on the sugar in the dough to create gases and alcohol, something which lends a very distinctive flavour and aroma. Yeast is most effective, when used with a dough which is high on gluten, a starchy substance found in wheat which also aids in trapping the gasses in the dough. And that is why it is most effective with wheat flour dishes.

This was regarding some aspects of baker’s yeast.

The above article dealt with understanding of yeast and  is based on the information given in the following links :-







I shall be dealing with behaviour of yeast during baking and the terms like proofing, knock down, kneading the dough properly etc. in my subsequent post.

Related articles  Basic  steps involved in Bread Making

 Cake Baking Mistakes 

 Tips for Baking a Good Cake     

Importance of Sifting Flour 

  Importance of Preheating    

Tips for making Perfect Whipped Cream     

Olive Oil Types and its Uses

Difference Between Baking Soda and Baking Powder


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  1. Panchatapa Deb
    • Samira
  2. Jaunita
    • Samira
  3. Anonymous
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