What are the benefits of sourdough and why might you choose to use it over commercial yeast?
This is a great question that I see very often. There has been a recent resurgence in interest around sourdough for the home baker. It seems new and is trendy but the use of sourdough has a very long history, in contrast the more familiar commercial yeast has been used just since the late 1800’s. Let’s explore the difference between sourdough and commercial yeast and take a closer look at the benefits of sourdough.
Yeast Differences
Both Sourdough starter (wild yeast) and commercial yeast have the same main job – to ferment and provide lift to breads. There are however some distinct differences, one major difference is the impact on digestive health. Other differences include how the yeast are produced and harvested, and the time in which it takes for them to act in a recipe.
Basic Sourdough Info
Naturally occurring yeast that lives on grains and in the air is referred to as wild yeast. Yeast most commonly found in sourdough starters are varied and depending on the origin can include Kazachstania exigua, Saccharomyces cerevisiae, K. exiguus and K. humilis. Also present in sourdough is the bacteria lactobacilli which can have a positive impact on digestive health.
Sourdough requires a starter, a live colony of yeast to be used in baking. Sourdough starter is created by mixing flour and water together and allowing it to ferment. Specific ratios of flour and water create an environment that is friendly to wild yeast and encourages the yeast to grow and multiply. This yeast becomes a colony that can be fed and used over and over again. The longer the colony is maintained and used the stronger it becomes which results in better and more reliable leavened breads.
Since these yeasts are naturally occurring in the environment, there is a theory that the more sourdough bread you bake the larger the colony within your environment becomes and produces better and stronger breads.
Sourdough is really a culture, like yogurt. The wild yeast organisms live off the carbohydrates from the flour and produce ethanol and carbon dioxide which is then converted by bacteria into lactic acid, a fermentation process that produces the chewy, airy texture within the bread.
For a bit more science around sourdough and its benefits, take a look at this great article from Cultures for Health.
Basic Commercial Yeast Info
Commercial yeast is from the single strain Saccharomyces cerevisiae species and is a member of the mushroom family.
Also known as Baker’s or Brewer’s Yeast, commercial yeast is grown in controlled conditions, usually in large vats, and harvested in huge quantities. It is then processed into a few different types of yeast, which we’ll talk about later.
Commercial yeast acts more quickly than sourdough which is why it is a popular option. This yeast produces carbon dioxide gas which contributes to the internal structure of the bread making it rise.
With the exception of fresh yeast which should be stored in the fridge or freezer, commercial yeast is typically sold in a dry, shelf stable form and does not need to be maintained the same way a sourdough starter does.
Wonderful Benefits of Sourdough
Sourdough starter has a longer fermentation process, meaning it takes longer for bread to rise when using it as the leavening agent. This is actually one of the benefits of sourdough. This longer fermentation process breaks down the proteins in the baked goods, like gluten and simple sugars, and pre-digests them so that it’s easier for human digestion and has less impact on blood sugar.
In contrast, commercial yeast acts quickly and does not have a chance to break down and pre-digest the proteins or simple sugars in the bread which can make bread more difficult to digest and have more of an impact on blood sugar. .
A Short History of Sourdough & Yeast
Sourdough was used as the primary leavener for breads up until our recent history. Used in ancient Egypt and assumed to have been discovered by accident, sourdough was used throughout the ages.
It’s only been within approximately the last 100 years that commercial yeasts have been used. Yeast, as we know it today, came into commercial production in 1879 and quickly became a major industry.
Now commercial yeasts are the standard for use in breads sold at groceries and in modern recipes because of the speed of production and wide availability to commercial bakers and the general public, while sourdough is typically used in artisan bakeries and by small batch bakers.
Choosing a Yeast for Home Baking
The choice to use commercial yeast instead of or in addition to sourdough is typically for ease, availability, and speed. It takes a bit of time, knowledge, and resources to maintain a sourdough starter whereas using a commercial yeast is fast and easy. However, a sourdough starter can be maintained for an extremely long time which makes it a renewable resource.
Speaking of resources, there is a cost associated with both buying yeast and commercially baked bread or keeping and maintaining a sourdough starter. While I have not done my own cost analysis I found this super interesting article from Stepping Stones of FI examining the cost difference of baking at home versus buying bread at the store.
Deciding which kind of yeast to use comes down to a handful of factors. Time, the recipe, what you have on hand, and personal preference. Most baked goods recipes can be converted to a sourdough recipe with some basic measurement adjustments if sourdough is the preferred leavener. I find one of the most common deciding factors is time.
Sourdough Starter
Maintaining a sourdough starter requires time for regular maintenance, getting the starter to peak activity for a recipe, and requires a longer rising/fermentation time. Rising/fermentation time will ultimately be dictated by the recipe, the temperature of the room, and type of bread you’re making but it could be anywhere from 3 – 10 hours, sometimes longer.
I tend to like recipes that have a long fermentation time and will often put the dough in the fridge overnight just to give a little extra time for the sourdough to do its thing. I find the longer fermented breads to be easier on my digestion.
Commercial Yeast
Commercial yeast however, has different forms which can activate a lot faster and take less time to rise making it possible to bake a loaf within a single day and even within just a few hours. And, of course, there is no time commitment for maintenance.
Typical rise times for commercially yeasted breads are anywhere from 40 – 90 minutes and depend on the recipe and warmth of the room. Longer fermentation times are not typically recommended for commercial yeast. Since this type of yeast acts so quickly it really plows through it’s food source very quickly. If left too long the recipe can over-proof which affects the rise and texture of the final product.
There are three kinds of commercial yeast available. One is instant yeast which is a powdered form that can be added directly to a flour mixture and when liquid is added to the mixture that yeast is activated.
A second kind of is active dry yeast which is granular and needs liquid to activate. Ideally warm liquid with a little bit of sugar to wake up the yeast.
The third kind is fresh yeast. This yeast is not easy to find and is not typically available in grocery stores. It comes in a brick shape, is soft and is added to a bread mixture and activates immediately. Fresh yeast must be stored in the fridge or freezer.
Combining Sourdough Starter and Yeast
Commercial yeasts can be used in combination with sourdough starter to get a rise out of a bread product and to make a sourdough recipe faster. Using a commercial yeast alongside sourdough may diminish the digestive effects of the sourdough because the sourdough starter does not have an opportunity to break down the proteins and sugars as it would on its own with a longer ferment. However, getting an extra boost from commercial yeast in recipes that include eggs, milk, and butter is very helpful and can save time.
Choosing the type of yeast for a recipe is ultimately a personal decision. There is room for sourdough and commercial yeast in the home kitchen and it basically comes down to what you feel is most advantageous for you and the results you’re looking for. I hope this article gives you some food for thought, pun intended, regarding the benefits of sourdough.
Sourdough Starter Resources and Additional Yeast Information
My sourdough starter is from Homestead and Chill. Other great places to get a dried sourdough starter with activation instructions are Ballerina Farm who has some sourdough kits and Untamed Farm.
Check out this great Youtube video comparing sourdough and commercial yeast from The Regular Chef.
