How to Fix an Acidic Sourdough Starter

Why isn't my sourdough starter doubling anymore? It was doing great!

 

When suddenly your starter stops rising, acidity is one of the most common causes.

This week, I received an email from a customer stating that her sourdough starter started off strong, making good loaves, but suddenly isn't bubbly at all. Through our chat, I was able to get to the bottom of her issue, and wanted to share the solution with you all as well.

Four factors that can contribute to sourdough starter acidity, and their solutions:

1. Temperature. Your sourdough starter is primarily a mix of yeast and lactic acid bacteria (LAB). A healthy sourdough starter has these microorganisms in balance. At lower temperatures, yeast cells slow dramatically, while the LAB tolerate a higher range of temperature. When a sourdough starter is fed with cold water, the LAB population grows quickly while the yeast cells struggle to keep up. These bacteria excrete acids as their waste; this is what creates the signature sourdough flavor, but too much acid becomes a feedback loop, weakening your starter as it becomes more and more acidic. Using warm water when feeding (around 85F) creates the ideal temperature conditions to keep both the yeast and LAB populations in balance. Additionally, try to find a warm spot in your home (between 75-80F) to store your starter if possible. 

2. Rye flour. Some people use large amounts of rye thinking it will boost their starter. Rye contains a high volume of amylase. The microorganisms in your starter will devour this quickly, then run out of food. If left in this starvation phase too long, the yeast cells will die off while the heartier bacteria continue to thrive. As with the temperature piece, this leads to increased acidity over time. Wheat is a slower food source for the culture, so using primarily bread or all-purpose flour keeps the starter our of starvation mode. The other solve for this is more frequent feeding (adjusting the ratio, or feeding 2x per day)

3. Fresh milled flour. There's nothing wrong with using fresh milled flour at all, but it is more nutrient dense. As with the rye, it is faster fermenting, supercharging the starter's normal feed cycle. This issue can be solved by a higher feeding ratio, by using a 50:50 blend of fresh milled and "regular" flour, or feeding more frequently. 

4. Underfeeding. If your starter is fully receding before its next feed, it is being underfed. As with the rye and fresh milled flours, this leads to LAB overpopulation, and an acidic starter. Increase your feeding ratio, or feed more frequently.

Acidic Starter Rescue Procedure:

How to rehabilitate an acidic sourdough starter

Getting your starter back in balance takes just a couple days of purposeful feeding. 

  1. Retain 10g of your sourdough starter in a clean jar.
  2. Feed 50g bread flour or unbleached all-purpose flour, and 35g warm (85F) filtered water). It should be like a thick paste. If it is too hard to stir fully, add a splash of water. 
  3. Repeat this feed after 24 hours. 

I also recommend the following posts to evaluate your starter's health regularly:

How to Find Your Starter's Perfect Feeding Ratio

Adjusting your Starter for Winter

Sourdough Starter Ratios Explained


When you purchase a mature sourdough starter from Yeast Coast Sourdough, you aren't just getting a strong, robust starter. You are getting access to personalized help from real bakers, every step of the way.

Ready to get started? Get your Yeast Coast Sourdough Dehydrated Sourdough Starter 

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