This is part 1 of a three-part series examining the flavor of sourdough bread, and how to adjust it to taste. Please complete the series by reading part 2 and part 3.

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On the Baker’s Hotline we often hear from frustrated sourdough bakers who want to know how to change their starter in order to increase the sourness of their sourdough bread: “No matter what I do, I’m just not able to get the sour flavor I’m looking for!” In addition, there are others who complain that their bread is too sour and want to create a milder starter. 

While bakers may diverge when it comes to the flavor they’re looking for, they’re united in wanting to know how to successfully manipulate their starters when it comes to sourdough flavor development. Not surprisingly, there’s no simple, foolproof way to “manage” your starter to produce bread that’s more or less sour. Still, there are three specific factors that can really affect your bread’s flavor:

  1. The health of your starter
  2. The level of the bread dough’s organic acids
  3. The complex relationships over time between levain, dough, fermentation, and proofing

I suspect you’re anxious to start experimenting with all these elements of your bread baking like a sourdough scientist. But before we can get into the fun stuff, we need to master the basics: in this case, creating a healthy, vigorous starter — the subject of this initial post. Once we master this, we can dive deeper with parts 2 and 3 of this series.  

Feeding sourdough starter Kristin Teig
Flour and water: that's all your starter needs to thrive. But how and when you feed it can make a big difference in its health.

What makes a great starter? 

According to Debra Wink, microbiologist and nationally known sourdough expert, “For the mother culture, the objective is to build and balance healthy populations of yeast and bacteria with enough collective power to do what you want them to do later.”  

Translation: First, build and maintain a healthy starter. Once you’ve done that, you can take that healthy starter and use it as the basis for great sourdough bread, bread whose sour flavor you can tweak as desired during the preferment and dough stages.  

If you already have an active, healthy starter, one that reliably doubles in size within six to eight hours of being fed and consistently produces flavorful bread with a good rise, then more power to you — we never argue with success! The maintenance regimen you follow for your starter obviously works well in your environment.   

But if the bread you bake isn’t rising or delivering the flavor you’re looking for, then maybe it’s time to think about how you care for your starter.  

Know and understand your starter 

Two of the key components of sourdough starter are yeast and lactic acid bacteria (LAB). To make bread that both rises well and delivers hearty flavor, we need to strike a balance that nurtures healthy populations of both. LAB are almost always present in larger numbers than yeast, although populations will vary from one starter to the next and at different times during the fermentation cycle.

Often, nourishing healthy populations of both yeast and LAB in your starter is actually about creating an environment that suppresses the LAB enough so that the yeast can still function well.

All things being equal, yeast would be glad to dwell and reproduce in a warm, wet, whole grain environment, just like LAB. But in order for yeast to stay competitive and perform as it should, it’s sometimes helpful to control conditions enough so that LAB are a little more challenged. This helps yeast hold its own, or even flourish and expand.

Conditions that keep LAB in check Conditions that favor LAB
Stiffer consistency (less water) Looser consistency (more water)
Cooler temperatures Warmer temperatures
Feeding when less ripe* Feeding when more ripe*
Smaller, more frequent feedings Larger, less frequent feedings
White flour (all-purpose or bread flour) Whole-grain flour (especially rye)

*Note: Less ripe and more ripe may sound confusing; ripe is ripe, right? But there’s typically an extended window of time when your starter is considered ripe (from the early moments of peaking, until it’s just beginning to fall). “Less ripe” means on the early end of the window, while “more ripe” is later on in that window. This window of time can vary in length from one starter to the next, and with varying conditions and feeding schemes.

Different types of starters and preferments arrayed on a table. Martin Philip
Starters, and the preferments made from them, can vary widely in consistency (loose vs. stiff) and in the flours they're fed with, which can range from all-purpose (white) flour to whole grains like wheat and rye.

Reaching middle ground

Picture the relationship between yeast and LAB as a spectrum between two poles: The conditions under which you maintain your starter can shift the balance more toward yeast or more toward LAB, but these conditions always affect yeast and LAB in relation to each other. For instance, if you maintain your stiff starter at cooler temperatures, this will discourage LAB a little more than it does yeast. Yeast aren’t growing wildly under these conditions, and LAB aren’t dying out. It’s just shifting the ratio a little so that the yeast can do their part.

What we’re after, in the end, is a golden middle ground for your starter — one where both yeast and LAB are able to thrive and function at their best, enabling your starter to both raise your bread and affect its flavor.

But what does that middle ground look like? Should your sourdough starter be stiff or liquid? What’s the best storage temperature? Which flour should you feed it with — and how often, and how much? It helps to think of the golden middle ground as more of a region between those poles rather than a precise destination. You can create wonderful, high-rising, flavorful bread with many types of starters. 

If you’ve purchased our sourdough starter or followed our starter recipe you have a liquid white flour starter (100% hydration: equal parts flour and water by weight). This type of starter definitely falls in that middle ground. But if you have a stiff starter or a whole wheat or rye starter that’s delivering the results you want — then consider yourself golden! 

In addition to finding balance and nurturing both yeast and LAB populations, how you maintain your starter matters. But just like reaching that sought-after middle ground, there are lots of ways to maintain a healthy and active starter. In the end, the most important consideration is whether or not your starter is delivering the results you want. 

Sourdough starter in a glass mason jar, waiting to be fed. Liz Neily
A healthy starter will start to expand and bubble within a couple of hours of being fed.

Taking care of business 

So how do we cultivate healthy populations of both yeast and LAB in our starter? 

We follow the CARE model:
Consistent
Adequate
Responsive 
Easy

Consistent (feedings): Changes such as shifting the variables of hydration, flour type, or amount and frequency of feedings will require time for your starter to adjust. A new feeding routine will change the balance and may even promote different microorganisms, and it takes time for these changes to settle into a new equilibrium.

Major changes like shifting from a white flour starter to a rye starter will likely take up to 10 days of room temperature feedings for the starter to completely make the conversion. This doesn’t mean that you can’t use your starter in the interim; just don’t expect to realistically evaluate the qualities you’re looking for in a new starter until the adjustment is complete.   

Sometimes major changes can even adversely affect the consistency of your starter or produce a strange aroma. Don’t worry! Just keep feeding until your starter has had time to adjust to its new diet or conditions.  

Adequate (room temperature feedings): While most mature starters can survive quite nicely when stored in the refrigerator and fed once a week, they won’t necessarily thrive under those conditions.  

Allowing time for your starter to ferment at room temperature through at least a few feeding cycles serves to build, strengthen, and rebalance the populations of yeast and LAB you’ll need to get the job done when it’s time for baking bread.   

This is particularly true if you’re planning to bake a recipe that’s naturally leavened (no added yeast). The number of “revival” feedings necessary depends on how long your starter has been in the refrigerator, and how quickly it begins to behave like an active, healthy starter.  

Responsive: For a 100% hydration starter, which is composed of equal parts by weight of starter, water, and flour (1:1:1), we recommend feeding twice daily at room temperature and at least once a week when stored in the refrigerator. This regimen should create a healthy starter, one that reliably doubles in volume within six to eight hours after feeding at room temperature and has a pleasant (or at least not unpleasant) aroma.

However, there may be times when your starter doesn’t do well under this maintenance routine. You may notice your starter rising sluggishly, or barely at all. Or it may have an unpleasant aroma: think acetone (nail polish remover) or another “funky,” nose-averting smell. We’ll address possible fixes further on in this article since it’s important to respond appropriately to these warning signs.

Easy: Make the feeding process as easy as you can and you’re more likely to follow it consistently. Here are some tips for success: 

  • Set times of the day (or time of the week) for feeding, put it in your calendar, and stick with it.  
  • Don’t worry too much about creating the perfect room temperature, unless your home is very cold or very hot, temperature somewhere between 68°F and 80°F should be fine.
  • If you find that feeding your starter several times in preparation for baking is generating more discard than you’re able to keep up with, consider maintaining a smaller starter, one that will generate less discard. 

Adopting this CARE routine for your starter will create a firm foundation for using that starter to leaven and flavor your sourdough bread.  

Sourdough starter in a glass jar on a scale being fed with water. Kristin Teig
For best results, the temperature of the water you use to feed your starter should complement the environment in which the starter will rise. If your kitchen is hot, use cool water; if the kitchen's chilly, feed your starter with warm water.

How to help your underperforming starter 

What do you do when your starter just isn’t responding well to regular feedings? It may take more than 12 hours to barely double in size; or it may have developed an unpleasant “off” odor. 

Here are some factors that might be responsible — and how you can address them. 

Adjust the water temperature. Seasons change, and cooler temperatures in your kitchen may be causing your starter to slow down — or in hot weather, to rise and fall too rapidly. Feeding with warmer water in the winter will help speed up fermentation, while cooler water in the summer will help bring the starter back to its temperature comfort zone.

Don’t let your starter fall completely between feedings. Yeast prefers being fed when your starter is ripe or a bit less so, while LAB are surging ahead as the starter moves past ripe — so feeding near the starter’s peak keeps both sides strong.

Take advantage of your refrigerator. While it’s best to feed your starter near its peak, we understand that life intervenes and it’s not always possible. In that case refrigerate your starter, which will slow everything down and extend the optimum feeding window.  

Adjust the ratio of starter compared to flour and water. Our 100% hydration starter, with its ratio of 1:1:1 (starter:water:flour, by weight) generally does well under moderate to cool conditions. However, if you’re in a warm environment (whether due to season or climate) you may find your starter peaking too early and falling too soon rather than lasting until the next feed.  

Since feeding your starter more than twice daily can quickly become tiresome, here’s how to slow things down: change the 1:1:1 ratio to something like 1:4:4. Since a larger meal takes longer for your starter to consume and ferment, increasing the amount of flour and water you’re feeding relative to the amount of starter should slow things down and bring feeding times closer to your ideal of twice a day.*

*Don’t be alarmed if it seems to take quite a bit longer for your starter to get going when you first switch to larger feedings. The bulk of activity will occur during the final few hours.

Worried about too much discard when feeding 1:4:4? Simply reduce the amount of starter you’re feeding. For example, instead of feeding 50g of starter with 200g of water and 200g of flour, start with 25g of starter and feed with 100g each flour and water. If this still sounds like too much discard, consider maintaining a smaller starter. For our smaller starter recipe, a 1:4:4 feeding would look like this: 7g starter + 28g water + 28g flour.

Next time: Where does flavor come from? 

Now that you’ve learned how to maintain a healthy starter — one that balances the needs of its two key components, yeast and LAB — you’re ready to take that starter and bake some delicious bread with the flavor you want. Our next post will examine exactly where the sour flavor comes from in sourdough bread.  

Continue the series:
How to make your sourdough bread more (or less) sour: part 2
How to make your sourdough bread more (or less) sour: part 3

Our thanks to microbiologist and sourdough scientist Debra Wink, without whose knowledge and insight this article wouldn’t have been possible.  

Cover photo by Liz Neily.

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Barb Alpern
The Author

About Barb Alpern

Long time professional artisan bread baker, caramel maker and member of our Baker Specialist team, Barb grew up in Ann Arbor, Michigan and has four grown sons. She has baked in Michigan, Maine, Vermont, and Texas (if you count baking cookies for her son's wedding!).

View all posts by Barb Alpern