Lactic and acetic acids make a good loaf of sourdough taste pleasantly sour. Lactic acid adds a flavor that is smooth and creamy, like yogurt, and acetic acid adds a sharper, vinegar-like tang.
Some bakers might think that only acetic acid makes sourdough sour because it is stronger. The truth is that these acids work together in sourdough to give it a complex and satisfying flavor.
If the taste of your loaves isn’t quite right, you can change the levels of these acids in your sourdough in a million different ways. But after working as a professional baker for years, here are the best ways I’ve found to make sourdough more sour.
How To Increase The Sourness Of Your Sourdough
1. Mature Your Starter Before Using It
If you just got your starter, it might not be ready to use in a bread recipe. After you feed a ready starter, it should double in size in 4 to 6 hours.
Even if you make a pre-ferment for your bread, like a biga, poolish, levain, or sponge, the age of the starter you add to it will have a big impact on this first stage of flavor development.
Check out this article on How to Strengthen Sourdough Starter if you are having trouble getting your young starter to mature and rise consistently. The next thing on this list will also help a sluggish starter culture get going again.
2. Feed Your Starter Whole Grains
Are you using 100% bleached (white) all-purpose flour or bread flour in your starter? This is a common problem that can make the taste less good and the starter less active.
Giving it 50% whole-grain flour and 50% white flour can make it taste better and help a new starter grow up faster.
Whole wheat will work, but rye flour is the best choice if you want to use a whole grain. Rye has a unique mix of sugars that make it easy for acetic acid to be made. It’s also full of natural yeasts and bacteria that help your starter ferment faster and taste better.
3. Feed Your Starter Less Frequently
If you let your starter get a little “hungry,” it will make more acetic acid, which will make the starter more sour.
If your starter is already old enough, you might want to feed it every 1–2 days. This should help your starter get more sour while still giving it enough food to keep going.
4. Increase Fermentation Temperature
Another way to increase the sour flavors in your starter is by simply increasing the temperature during fermentation. Aim for a temperature between 75 and 82°F to make your starter more acidic.
5. Increase The Hydration Of Your Pre-Ferment
A pre-ferment gives you another chance to make your bread taste more sour. This consists of a mixture of flour, water, and a mature sourdough starter.
Try to get your levain or other pre-ferments to as much as 125% hydration. This extra water will make the bacteria that make lactic and acetic acids work harder. That will give your pre-ferment and final loaf more sour flavor.
6. Increase The Temperature While The Pre-Ferment Is Rising
Like raising the temperature of your sourdough starter during fermentation, raising the temperature of a pre-ferment can help it get a little bit more sour.
Again, aim for a temperature range of 75-82°F while it’s set aside to rise. Keep in mind that the temperature increase may make it rise faster than you’re used to.
7. Use Whole Grains
Adding whole grains, especially rye, to your bread flour mix boosts yeast and bacterial activity, just like a sourdough starter does. This means more sourness!
Aim for 10–15% rye or whole wheat in your flour mixture to get good results without making big changes to the rest of your recipe.
8. Use Warmer Temperatures During The First (Bulk) Fermentation
This is another way in which increasing the temperature is used to make more acid and flavor. During the first fermentation, or bulk fermentation, of your bread dough, keep it in a warmer place to help the flavor develop.
You can push the temperature to as high as 79-83°F. As the temperature goes up, so does the rate of fermentation. So, if you use this method, be careful not to let your dough rise too much.
9. Refrigerate Your Dough During Its Second Fermentation
As you may have noticed, temperature plays a big role in acid production and the sourness of your bread. And while higher temperatures usually lead to more flavor, this method uses lower temperatures to make the sourness stronger.
After you’ve shaped your bread and it’s time for its last rise, putting it in the refrigerator can make its sour taste even stronger.
When you do this, the cooler temperatures bring out more of the flavors of the lactic acid. These flavors are creamier, but they are also tangy like yogurt and have a nice mix of different tastes. And just like warm temperatures speed up fermentation, cold temperatures slow it down. So your final proof may need to be longer.
10. Keep The Recipe Basic
For an extra sour sourdough bread, keep it simple. For maximum flavor, a classic sourdough loaf should only contain flour, water, and salt.
Adding rich ingredients like oils, butter, or milk will dull the flavor of your starter, undoing all the hard work you did to make it zing.
Because there are so many factors at play together, any one of these actions by itself may not guarantee a more sour loaf. Some things that can change how your bread tastes are the temperature of the room, the temperature of the water, and how old your starter is.
As you try different ways to make the taste you want, the goal is to find a good balance between all of these things.
Be mindful as you tinker with increasing temperatures and hydration for stronger sourness, as they can lead to more rapid fermentation. See how far you can go without letting the dough rise too much.
Finally, tracking your progress in a baking journal is a great way to help you learn what’s working and what isn’t. Even if you use the same steps every time, your loaves will probably still come out slightly different. That’s just how exciting it is to work with sourdough that is still alive.