Thoughts On Preferments and Sourdough

When I first began my bread baking journey, I thought all bread was made with commercial yeast. Boy, was I wrong. It seems everyone is baking bread these days during quarantine, but there’s only one bread that’s really stealing the show. You guessed it – sourdough! 

BUT, I don’t really like to call it sourdough. I much prefer the term “naturally leavened.”

Naturally leavened bread is made only from leaven that you effectively create out of thin air by mixing flour and water, and then continue to feed the microorganisms that live within that micro ecosystem, commonly called a “starter.” If you continue to feed the wild yeast and bacteria, you can bake bread from it indefinitely. Indeed, some starters are handed down from generation to generation. There is usually no commercial yeast added to make the bread rise, only the microorganisms that exist in the atmosphere, flour, and the baker’s hands. This method of baking bread has existed since the beginning of time, and has more in common with European bread making traditions.

During a recent conversation with my brother, I was gushing over how much fun it has been to bake sourdough this past month. I tried to convince him that his engineer brain would go nerd-mode obsessed over the sourdough baking process too. His first response was, “I don’t know. I don’t really love the taste of sourdough. It’s too SOUR.” Whoa, hold up. This is why I abhor the term sourdough. I too used to think that every bite of sourdough had to finish with an acrid sour taste in the back of your tongue. False! All naturally leavened breads are considered sourdoughs, but these days many bakers avoid using this term because it is often associated with a highly sour bread. In reality, there is no particular “sourness” needed for sourdough, and many people actually prefer the acidity in their sourdough to be more mild. In effect, the possibility of a sourdough taste profile is infinite, and relies on temperature, baker ratios, type of flour, maturity of the levain, hydration, among other factors. This idea of sour sourdough originated during the 19th century, when San Franciscan sourdough became world-famous for its pleasant sourness, if you like that sort of thing. Food scientist Robert Wolke explained its uniqueness best on NPR: 

“The sour flavors come from lactic and acetic acids produced by inevitable environmental bacteria, which are working on the flour’s sugars along with the yeast. Different bacteria make different sour flavors; San Francisco is awash in local bacteria species that make its sourdough bread famous. So sourness per se in some ryes and many other breads is quite desirable.”

While the idea that an area’s microbiome effects the taste of the resulting bread remains contested, I am fervently open to the idea. It fascinates me that naturally leavened bread in France will never taste like a Californian sourdough due to the differences in yeast and bacteria in the atmosphere. Whether this idea is based in fact or not, a baker can still control the acidity of the bread by adjusting the aforementioned variables of the bread baking process. These days, many bakers throughout the world (including San Fran) are opting for milder naturally leavened breads. In fact, many French bakers would balk at the level of acidity of the famous San Franciscan sourdough loaf. 

Preferments Defined

Another confounding factor that confuses new bread bakers to no end, is that many terms used in bread baking differ based on the region of the world you live in. Terms can be used interchangeably, and are often in another language. Uff-da. Based on my extensive research on the topic, and on my own journey to learning how to bake naturally leavened bread, here are some definitions I have found to be generally accepted by the baking community: 

Preferment: King Arthur Flour defines preferment as “a preparation of a portion of a bread dough that is made several hours or more in advance of mixing the final dough. The preferment can be of a stiff texture, it can be quite loose in texture, or it can simply be a piece of mixed bread dough. Some preferments contain salt, others do not. Some are generated with commercial yeast, some with naturally occurring wild yeasts.” To put it simply, this is the overarching term used to refer to the leaven, one you naturally made or commercial yeast you purchased, that are allowed to ferment on their own before being added to your bread recipe.

Starter: (aka “levain” or “wild yeast colony”) a preferment made only of wild, mature sourdough culture. If you feed your starter routinely, you can use the same starter indefinitely. You will often times see the French word levain and starter used interchangeably, but some bakers only use the word levain to describe the portion of starter that actually went into the bread recipe. 

Levain: (French for leaven) what many bakers refer to as the post feeding portion of the starter that you use in your bread recipe. Some recipes will call for you to remove a portion of your starter and feed it with different flours and ratios of water, so you don’t effect the composition of your original starter. In other words, you can experiment more with the portion of the levain you remove from your starter for different breads, but you generally don’t want to alter your mature starter, so you can continue to use it over and over in the future. This term was used before commercial yeast was available, therefore there was previously no distinction between the two. 

Commercial yeast: We all have heard of about commercial baker’s yeast that you can buy to leaven dough. It is made up of one strain of yeast that is cultivated commercially and sold in a dried form or in other various mediums. We need to remember wild yeast occurs naturally in the environment, as well as in flour. Before yeast was made readily available in stores, all bread was naturally leavened, and today these breads are considered sourdough bread. Commercial yeast is used in pâte fermentée, poolish (french), and biga (italian). 

• Pâte Fermentée literally means fermented dough in French, and is sometimes referred to as old dough. It contains all the components of finished dough, including flour, water, salt, and yeast, and is allowed to ferment for a period of time before adding to the final bread recipe. 

• Poolish is the French word for leaven, but it has Polish origins. It is a mixture of 50/50 water and flour (100% hydration) and yeast that is allowed to ferment prior to adding to the final bread recipe. 

• Biga is the Italian word for preferment, and is it usually stiffer, or less hydrated, than Poolish. It is also a mixture of flour, water, and yeast. Notice that both poolish and biga do not contain salt, which is what differentiates them from pâte fermentée. 

Naturally Leavened (sourdough) Myths Busted

1. You don’t have to feed your starter every day. This comes from professional bakers who typically bake bread every day, therefore for them it is necessary for them to feed their starter for every day use. Life over loaf, not loaf over life.
2. You don’t have to actually throw away sourdough discard every time you feed your starter. You should only make enough starter you need plus “scrapings” leftover in your starter to continue to feed and grow it for later use. However, if you enjoy making recipes from your sourdough discard, here are some awesome recipes (we love making KA discard biscuits in the morning at our house.)
3. Don’t use cheap flour to make a starter “because you’re just going to throw it away.” We want to use quality organic natural bacteria and yeast environments, not wheat that’s been sprayed with pesticide. Flour used in the starter will reflect in the taste of your final baked bread. 
4. Sourdough starter can’t die (usually). The starter relies on food and temperature, so changes in these variables may effect the puff of your starter. That doesn’t mean it’s dead. If it has collapsed, it has already reached peak puff and feeding; maybe you didn’t feed enough flour food, or maybe your kitchen is too cold. Losing volume doesn’t mean it has died, it means it ran out of food. When it’s sleeping in the fridge it will deflate a little and have water on the top, so you just need to re-feed. 
5. Sourdough doesn’t need to be very wet. It just depends on what you’re trying to achieve in your final loaf – drier and tighter or a more open crumb. Higher hydration will give you more open holes, so it just depends on the hydration you use.
6. I know I’m starting to sound like a broken record, but not all sourdough (naturally leavened bread) needs to taste acidic. Consider how or where the sourdough was made, as some bakeries or regions may make sourdoughs you don’t like. 
7. The only requirement is that flour water and salt makes naturally leavened bread. Sourdough doesn’t need to fit any flavour profile or particular method. They all are correct methods! Never say “sourdough should…” 

If you have any questions or contributions, please comment below. I would love to hear your thoughts on sourdough. Happy quarantine bread baking! 

References: 

Forkish, K. (2012). Flour Water Salt Yeast: The fundamentals of artisan bread and pizza. Ten Speed Press.

Preferment (Unknown date). King Arthur Flour. Retrieved May 21, 2020, from https://www.kingarthurflour.com/pro/reference/preferment

Sourdough Myths Busted – Bake with Jack (2019, September 4). Bake with Jack. Retrieved May 21, 2020, from https://www.youtube.com/watch?v=2s1vWpcjfUI

What is the Difference Between a Starter and a Preferment? (2011, March 22). The Fresh Loaf. Retrieved May 21, 2020, from http://www.thefreshloaf.com/node/22810/what-difference-between-starter-and-preferment

What’s the Difference Between a Starter and a Levain? (2020, May 3). Knead Rise Bake, Simply Baked Bread. Retrieved May 21, 2020, from https://kneadrisebake.com/whats-the-difference-between-a-starter-and-a-levain/

What’s the Difference Between Levain and Starter? (2017, October 4). Kitchn. Retrieved May 21, 2020, from https://www.thekitchn.com/what-the-difference-between-sourdough-starter-250218