Yeast Vs. Sourdough Starter (Understanding the Difference)

Yeast vs. Sourdough starter? Which is the best option and what is the actual difference between these two seemingly similar rising agents?

sourdough starter in a jar

If I am honest, and I am. To a fault at times. I didn’t “get” the whole sourdough starter craze of 2020. Suddenly, everyone was trying to make it and bake with it, and flour became a hot commodity.

Friends were online chatting about their sourdough struggles, and there I was with my perfectly risen yeast bread. Baking with whatever flour I was able to find. I wondered, were people this bored that they would go to what seemed like such painstaking efforts just to make a loaf of bread? So bored, that they would pass up using store-bought yeast that worked every, single time?

The answer of course was yes and no. Yes, people were bored and no it wasn’t about the boredom. Well, maybe it was a little. Yet, their efforts were worth it. It took me a while to surrender to sourdough, but the moment I did, my kitchen changed. I changed. A simple swap out improved our diet and I found myself passionate about sourdough baking.

So in this post, I plan to share just what those crazy people were up to and what the fuss is all about.

What is Yeast? 

​The word yeast can be confusing to the new baker. We see the word yeast in many recipes which likely refer to the sort of yeast I will be going over in the next section. But without going too far, natural yeast is actually a fungus. Surprisingly a living organism that broadly falls under the same family as the mushroom. When yeast is fed, or activated with water and flour it produces carbon dioxide which raises the dough. We will explore natural yeasts later on in the post.

What is Commercial Baker’s Yeast?

The more common sort of yeast you might think of is actually commercial bakers yeast. Commercial yeast comes in a variety of types either cake form or dehydrated. These types of store-bought yeast are fairly new to us in comparison to sourdough starter. This type of yeast,  saccharomyces cerevisiae, was created in a lab during the 18th century.

It is most commonly found in those little packets of Fleischmann’s active dry yeast. we are all so familiar with. Fleischmann’s was the first commercially produced yeast in America. At first, it was sold in a fresh cake state. which quickly gained popularity with home bakers.

Later, during the second World War, their laboratories produced a new active dry yeast that didn’t require refrigeration and activated quickly in warm water. More recently, in 1984 they introduced instant yeast which cut the rise times down significantly.

This sort of yeast does not contain any bacteria or wild yeast components. Moreover, this type of yeast feeds off sugar and delivers carbon dioxide at an extensive rate which results in bubbles that allow for bread to rise in as little as 30 minutes. 

Active Dry Vs Quick Acting Yeast

There are slight differences in a packet of your typical yeast. Quick-acting yeast or fast-acting yeast has much smaller granules than standard active dry yeast. These smaller granules eliminate the need to dissolve it in water before use. Given the smaller texture along with a few extra additives, quick-acting yeast will rise about 50% faster than active dry yeast.

You can interchangeably substitute one for the other in most recipes. Just note that the active dry yeast will take an additional 15-20 minutes for rise times than the quick or fast-acting yeast. While using instant yeast instead of active dry you can skip the rehydration step.

three different yeasts

What is Fresh Yeast?

Also known as cake yeast, this type is not as convenient for home bakers as it is sold in blocks and needs to be kept in the fridge. Usually found in the dairy section. This yeast is made up of about 70% water and only lasts about a week. Giving it a much shorter shelf life than its dehydrated counterpart.

It is most often used by commercial bakers rather than by home bakers who tend to prefer the convenience of dehydrated yeasts (above). Cake yeast is also not as readily available as dry active so you might have trouble finding it.

It is ideal for things like donuts, and sweet breads but can also be used for baking breads. It is especially useful in breads that require a slower rise time. Some claim that the use of fresh yeast over dehydrated, creates a tastier bread though I have not noticed any difference myself. Fresh yeast is to be crumbled and added to very tepid water before use. When swapping out dry active yeast for fresh, you will need to use twice the amount by weight than you would for active dry.


  • Both Active Dry and Instant Yeast are cheap and readily available
  • You can bake almost instantly without much more than a simple recipe to follow
  • Yeast speeds up the process of bread rising to as little as 30 minutes depending on the type used
  • Yeast is easy to use and simple to adapt to most recipes
  • Has a high success rate for use


  • Commercial Yeast is not a natural yeast, it was made in a lab
  • Saccharomyces Cerevisiae Yeast does nothing to the wheat itself so it will not produce any acids that break down gluten which helps make the bread more digestible
  • The bread made from this yeast processes quickly in our systems and spikes our blood sugar
  • This yeast will die at 140 degrees however, when in distress, as a coping mechanism it will send out little spores that become more yeast

What is Sourdough Starter?

The use of sourdough starters dates back to the days of ancient Egypt. It is amazing to think that we used this main method of leavening bread thousands of years ago and still use it today. Sourdough yeast is essentially a collection of wild yeast and natural bacteria  (lactic acid bacteria and acetic acid). It is characterized by the batter form and bubbly appearance when active.

The visual sign of its activity is all those bubbles in the batter after being fed. This can be seen easily when stored in a glass jar (preferably). However, some prefer to keep a dryer sourdough starter which simply means it contains less water. All sourdough starters essentially call for the same techniques when baking with them including a fermentation process for adequate dough rise. 

sourdough starter in a jar

Health Benefits Of Sourdough

Of course, we love the complex flavor that sourdough starter adds to home-baked breads. But its allure is found in the fact that it is a healthier alternative to eating regular bread made from commercial yeast. The lower phytate levels, in bread made with a sourdough starter make for an easier-to-digest food and result in a better more nutritious bread.

In sourdough, there is lactic acid bacteria present. This bacteria produces an enzyme called phytase. Phytase effectively “pre-digests” the phytic acid during extended fermentation.

It is a good alternative for those who are sensitive to gluten as sourdough is a fermented food that has a bacteria-to-yeast composition that works on breaking down the starches found in the grain before it’s even eaten.

Many people with IBS and gluten sensitivity can tolerate sourdough bread for this reason. However, in the case of celiac disease, one can make a gluten-free sourdough starter and there are several great gluten-free flours for baking. Such as King Arthur’s Gluten Free. 


  • Results in a healthier bread
  • A prebiotic food
  • Gives more complex flavors vs a loaf of store-bought bread
  • Easier on the stomach and a better option for people with IBS or who have a gluten sensitivity
  • A great natural option for baking
  • Is sustainable, a robust starter can last indefinitely
  • Makes for a great gift to share with others
  • Good for breads, cakes, muffins, or any sort of baked good that requires rising


  • Takes several hours and even up to two days to rise bread
  • More room for errors in the process when using wild yeast
  • Has a waiting period before using (after feeding)
  • Has a little of a learning curve
  • Has distinct taste that some might not favor

How is Sourdough Starter Made?

It might surprise you just how simply a starter can be made. With little ingredients and some time, you can make your own sourdough starter right in your kitchen. Essentially, you begin with a cup of flour and some water. This mixture is left out on the kitchen counter where it will begin absorbing wild yeast in the area. This is a completely different kind of yeast as it is wild.

The wild yeast is found in the flour you use and the air in which the starter is cultivated. It is referred to as the “symbiotic colony of yeast and bacteria” or a SCOBY which is a living organism. It takes several days to capture enough wild yeast to make a suitable starter that will in turn be active enough to rise bread. Typically it takes about 7 days of feeding, discarding, and sitting, to make a suitable starter.

One thing to understand when baking with a sourdough starter is that it is much more volatile and unpredictable than its counterpart. Bread can take several hours and even a couple of days to rise. So you must be patient.

Can You Combine the Two?

The simple answer is, yes, you can combine starter and commercial yeast in a recipe. I have added a little spoonful of active yeast to the water to give my sourdough loaf a little boost on occasion. It can be especially helpful when your starter is brand new or you want to bake but you forgot to feed your starter. After all, when baking with sourdough starter solely, you will want to use a robust healthy starter.

It is also common in recipes using sourdough discard as the discarded sourdough is not enough to raise the baked good. A simple boost from commercial yeast allows the home baker to use discarded sourdough that ordinarily might have ended up in the trash.

Some might argue the strain of yeast in commercial types might interfere with the mix of wild yeast within a sourdough starter. But I have not found anything to suggest this is the case. If you are looking to have the full benefits of sourdough starter, it is probably a better idea to stick solely with sourdough starter in your bread baking. But adding yeast to a bread recipe, while not always necessary, won’t hurt.

Can You Convert Yeast Recipes to Sourdough Starter?

After reading all the benefits of sourdough starter, you might be wondering if it’s possible to convert all your yeast recipes. The quick answer is, yes you can for the most part. This process might at first seem complicated but most of the time, anything new can appear this way. It is worth exploring if you are anything like me and want to maximize the nutritional aspect of the foods you make. This is an excellent way to do so.

Yeast Vs. Sourdough Starter

You could say that yeast and sourdough starter are polar opposites when comparing the two. When it comes to a leavening agent for home bakers many will find they favor one over the other.

When comparing the two, we know that commercial yeast was manufactured in a lab. While it has no natural benefits it does offer a much quicker rise for baked goods. While a sourdough starter is completely natural and therefore, filled with natural bacteria. This wild yeast works much more slowly yet yields a healthier bread overall.

So essentially, when comparing the two it is important to consider their benefits and any cons they might have for you. Begging the question, is a healthier quality bread worth the long wait and learning effort?

Prior to 2020, I might have answered differently. But these days, it is a resounding YES!

Happy baking!

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