Let’s talk about the fact that I’ve been struggling to get my sourdough starter, Steve to wake up these past few weeks. (Yes, I named my starter, and no it’s not weird!) I don’t know about you, but it’s been insanely cold in my area, and I’m talking frigid, nose-running, eyelash-freezing COLD.
If your sourdough has been sluggish lately due to the cold winter weather, then you may have noticed the flavor is not as sour as you remember.
Sourdough can be very temperamental, and like you and me in 10 degree weather, it wants to spend the whole day curled up in a blanket burrito. But don’t fret! Temperature is a common problem for changes in sourdough flavor, and I know just what you can do to fix it!
If your sourdough is struggling to pack its normal sour punch, I’ve put together a guide to help you restore that perfect sour flavor.
Why Does Sourdough Taste Sour?
Sourdough starter contains acids such as lactic acid and acetic acid which provide flavor to sourdough. Acetic acid is a byproduct of fermentation that contributes a vinegar-like tang. Lactic acid however, is produced from available lactic acid bacteria (LAB) giving sourdough its signature sour flavor.
Fermentation
Fermentation is the process in which organisms break down organic molecules anearobically (in the absence of oxygen). Organic molecules like yeast and bacteria break down sugars to produce lactic acid, acetic acid, carbon dioxide, and ethanol.
When it comes to sourdough flavor, and lactic acid specifically, LAB such as lactobacillus sanfranciscensis that produce primarily lactic acid are responsible for its sour flavor.
This process is known as lactic acid fermentation and is associated with other sour fermented foods like yogurt or kimchi. If you recall from my previous blog discussing what sourdough starter is, you’ll remember that carbon dioxide was a byproduct of fermentation.
Rather than contributing to flavor, it gives rise to your dough, making sourdough as an excellent leavening agent. To learn more about starter, check out my blog on what sourdough starter is.
Altering the sour flavor
Now that we know the process of fermentation and that flavor is affected by lactic acid production, we can adjust our starters to create a stronger or weaker sour flavor.
There are many factors that can affect flavor and the overall sourness level of your starter with the main contributors being, temperature, flour type, fermentation time, and starter quantity.
Temperature
- Warmer temperatures are ideal for lactic acid production. Fermentation is at its peak when temperatures are set around 75-80F. This range is optimal for yeast and bacteria to work hard consuming sugars and producing lactic acid. This makes it easier to make a starter from scratch during the warmer months of the year. Summer is prime time to leave your starter on the counter due to the warmer ambient air keeping fermentation active. However, during the colder months of winter, your starter may need a warmer spot in the house. Placing it on a warming mat or in the oven with the light on may be just enough heat to kick start more lactic acid production.
Flour type
- Flour type can also dictate the sourness of your starter based on the whole grain content. Whole grains contain 3 parts, the bran, germ, and endosperm. Most recipes call for using all purpose flour which only contains the endosperm where both the bran and the germ were removed during the milling process. The endosperm is a concentrated source of starch (sugar) that feeds yeast and bacteria. Whole wheat flours that contain all 3 parts of the grain like dark rye flour or freshly milled flour provide more natural sugars and nutrients than the endosperm alone. More available sugars lead to more lactic acid production. Simply switching the flour you use to feed your starter can, in itself, change the entire flavor of your sourdough.
Fermentation Time
- When baking with sourdough, fermentation time is crucial for that signature sour bite. Techniques like bulk fermentation require extended proofing times in a colder environment. Proofing your sourdough in the fridge will slow down the yeast activity while LAB continues to ferment. The longer it sits, the slower the dough will rise, and the more lactic acid is produced. If you’re in a pinch, leaving your dough on the counter to proof in a warmer environment can speed up the prep time. The downside is, you will lose out on the sour flavor with a shorter fermentation period.
Quantity of starter used when baking
- The quantity of your starter used when baking can be very straightforward when it comes to flavor. The more you use, the more sour the flavor. However, there is a more scientific approach than that. Adding less starter means adding a smaller amount of bacteria, and in turn, a smaller amount of lactic acid. Adding more starter to your dough, and thus more bacteria, means an increase in lactic acid production and overall sour flavor.
Summary
So there you have it! The solution to helping you get your sourdough starter out of the winter slumps and into cozy fermentation vibes. As a scientist and a baker, failure is imminent, but you can pick yourself up after falling.
As always, I hope this blog helped you become a better baker, so you can say goodbye to that seasonal sourdough depression, and hello to tangy, sour loaves!
