Select Country
Part I — How to Make Sourdough More (or Less) Sour
Whether you’re looking for a mild sourdough to pair with butter or a tangy, full-flavored bread that will stand up to a rich soup or strong cheese, these are the tweaks that can help you achieve your ideal sourdough.
We recently had the good fortune to attend a class at King Arthur Flour on the science of sourdough. The class, taught by microbiologist Debra Wink, focused on all the different tools the baker has to control the natural sourdough fermentation process. While Debra waxed poetic about six-carbon chains and weak hydrogen bonds, KAF pro baker Amber put us through our paces with two of King Arthur’s iconic sourdoughs: the mild and delicate Pain au Levain and the tangy Vermont Sourdough.
What we brought away from the class was a deeper understanding of the science behind some of our favorite sourdough tweaks. Below, we survey three key factors for influencing acidity in sourdoughs: temperature, flour choice and maturity. There are other factors as well, but these are the ones we find to be both easy to implement and highly effective.
Key Factors Influencing Acidity in Sourdough
| Table header 0 | Less Sour | More Sour |
|---|---|---|
| Mother culture (starter) | White flour Mature when fully risen Ferment at 70-76°F (21-24°C) | Some rye and/or whole wheat flour Mature after fully risen Ferment at 82-85°F (28-29 °C) |
| Pre-ferment (levain) | White flour Ripe at or before peak rise Ferment at 70-76°F (21-24°C) | Some rye and/or whole wheat flour Ripe after peak rise Ferment at 82-85°F (28-29°C) |
| Main Dough | Less whole grain/rye flour Rise to 1½ – 2 times volume Ferment at 70-76°F (21-24°C) | More whole grain and/or rye flour Rise to 2 ¼ - 3 times volume Ferment at 82-85°F (28-29°C) |
| Final Shaped Proof | Ferment at 70-76°F (21-24°C) | Ferment at 82-85°F (28-29°C) Retard at 40-50°F (4-10°C) |
Sources: Debra Wink, Michael Gänzle, Brød & Taylor
Equipment: Brod & Taylor Folding Proofer & Slow Cooker and/or Brod & Taylor Sourdough Home
Temperature: Temperature is the one variable that bakers can control at every stage of the bread making process, from mother culture through the final shaped proof. It’s an easy variable to manage using water temperature and a Proofer and/or a Sourdough Home.
- For less acidity: Use water around 80°F (27°C) and a fermentation temperature of 70-76°F (21-24°C) to favor the yeast and create milder flavors. When the mother culture is being kept at room temperature (for instance, for a few feeds leading up to bread making), consider giving it one or two short feed cycles, rising at 75°F (24°C) just until peaked.
- For more acidity: Use water around 90°F (32°FC) and consider fermenting the mother culture and preferment at about 82-85°F (28-29°C). This temperature is warm enough to begin to give desirable acid-producing bacteria (LAB) an edge, yet it won’t be hot enough to damage yeast populations which are necessary for the ongoing health of the culture and for good structure and rise in the bread.
Whole Grain and Rye Flours. Whole grain and rye flours provide minerals and enzymes that can influence acid production in sourdoughs. The higher mineral content of whole grains acts as a buffer in the dough so that more acid can be produced during extended fermentation. Additionally, the complex carbohydrate and enzyme content of rye flour helps produce unique sugars that tip the balance of acids in favor of acetic acid, which has more aroma and flavor and is more noticeable in the dough than lactic acid.
- For milder sourdough: Use less whole wheat and less rye, or consider sifting the bran out of whole wheat flour to create high-extraction flour. If using small amounts of whole grain, save it for the main dough, where it will have less time to contribute to acidity.
- For more tang: Incorporate some rye flour and/or whole wheat flour early in the bread-making process, such as when feeding the mother culture and the preferment. Rye flour in particular will help your culture produce some acetic acid.
Maturity. In our experience, tweaking maturity is a highly effective way to control sourdough flavor. This applies to refreshing the mother culture, fermenting the pre-ferment and rising the main dough (bulk fermentation). It does not apply to the final proof, because the point at which the shaped loaf is ready to bake should only be determined by the balance between gas production and structure. As Ms. Wink taught in her class, the reason maturity is so effective is that the acid producers (LAB) have a faster growth rate than yeast, so using the culture when it is more ripe quickly shifts the population balance towards greater numbers of LAB.
- To limit acidity: Refresh the mother culture when it has just risen to its final height. Similarly, use the pre-ferment when it has just peaked or even before the peak, and limit the initial rise (bulk fermentation) to a doubling of volume.
- To push for more acidity, Allow the mother culture to rest at its peak rise height for a while before refreshing. During the rest, the yeast population will hold steady while the acid producers (LAB) grow. Allow the pre-ferment to do the same – rest for a period after reaching its peak rise, then use it to mix the main dough. For the initial rise (bulk fermentation) allow the dough to rise more than double its volume. Many sourdoughs can rise to 2 ½ times their starting volume and some will do great with a threefold rise.
In part two of this series, we use these factors to play with our tried-and-true Country Sourdough Recipe.
Leave a comment
14 comments
I want my starter to be more sour, so I was delighted to find your article. Thank you! Donna
Great to hear, Donna!
There was a study done on the heterofermentative and homofermentative LAB in regards to temperature. The heterofermentative LAB are more present in colder temperatures and produce acetic acid (as well as some lactic acid and CO2). Acetic acid is more acidic while lactic acid is less acidic. The homofermentative LAB produces lactic acid, which is less sour. Lactic acid is known to have a more “creamy” flavor. Correct me if I am wrong but am I reading the opposite from this article. I have heard that rye flour makes your final product more acidic due to the heterofermentative LAB, which you have noted on the more tangy aspect. One reason is it is rich in amylase and sugars. The only thing I am seeing that conflicts with this article and the studies done is the temperature.
Josh: The discussion about the effect of temperature on LAB is an interesting one. However in this article, the focus is on the more broad competition between yeast and LAB. Lower temperatures favor yeast while higher temperatures favor LAB. Your point may be well founded. It is another layer of complexity. Just another reason why sourdough bread making is so fascinating.
I’ve been maintaining two starter for different types of bakes. The first the Country Sourdough and my own recipe modeled after the more sour profile. I’m using the B&T proofer. Recently I took a temp of the leaven with the proofer set at 83 F the internal temp was 89 F. The blog gives proofer temps for the less sour, but doesn’t specify proofer temp just a the temperature. My question Are the more sour temps specific to Proof temp setting or the internal?
David: All temperature recommendations are internal. We don’t specify a separate temperature setting for the proofer. Note that the proofer is calibrated to keep internal dough temperature the same as the proofer set temperature for open containers (such as a bowl) and using the water tray. When maintaining starter, the container is usually covered. This reduces heat loss out of the top of the container and causes the temperature of the starter to rise above the set temperature. (Think of the effect of placing a cover on a pot on the stove.) Good news is that this effect is consistent. You may find that to maintain your starter at 83 in a covered jar you will need to set the temperature to about 78. Make adjustments until you find the setting that works for you. We assume you are NOT using the water tray. Use of the water tray also will raise the internal temperature of the starter by a couple of degrees compared to no water tray. Good luck with your starters.
Good info…. Thanks
Thank you for your comment Joseph!
Do I cover the starter when I’m preparing it for baking?
Patty – We recommend keeping sourdough starter covered. It doesn’t need to be airtight. A lid loosely placed on top or a piece of cheesecloth secured with a rubber band will work.
I don’t to bake sd bread for the next three days. Can I simply leave my starter in my sourdough home and lower the temp to 45, then raise it after feeding to 80?
Linda – Yes, that sounds like a great plan for your starter. The cooler temperature will slow fermentation down enough so that you can go without feeding it for the next three days. It will be quite active and ready for baking after the next feeding at a warmer temperature.
Can I purchase a starter for sourdough bread from you?
Irene – We do not sell sourdough starter, but King Arthur Baking sell one that you can buy online.