Many factors impact how quickly sourdough rises. The most common changes are the amount of levain used and the proofing temperature. These can be used to control the rate of activity during the first and second rises. But there are more variables that speed up or slow down sourdough proofing, let’s take a look at them all.
The more acid bacteria and wild yeasts that are added to the sourdough, the quicker the dough will rise. Just like adding more yeast to a yeasted dough makes it rise quicker, increasing the amount of starter used in your dough will speed up the sourdough fermentation process.
If you want to rapidly increase the proofing speed of sourdough you can, if you wish, add some baker’s yeast to the recipe. A hybrid sourdough will have a lighter texture, taste and aroma, so can be quite pleasant. In my research, it is common to combine yeast and sourdough in commercial bread, and in many types of French bread. Although it shouldn’t be classed as sourdough by purists.
Another method to alter the rate of proofing is to change the temperature of the dough as sourdough ferments faster at warmer temperatures. This can either be done by adjusting the temperature of the dough at the end of kneading, this is called the Final Dough Temperature (FDT), or the temperature of the environment during the first or second rises.
The Final Dough Temperature uses a calculation to adjust the water temperature of the dough. First, the desired dough temperature is selected, which for sourdough and artisan bread, is around 25C (77F). Next, the flour and room temperatures are created and using the formula below, the temperature of the water is calculated:
WT = Ideal Water Temperature DDT =Desired Dough Temperature RT = Room Temperature FT = Flour Temperature KE = Kinetic Energy, which is 12 3 x DDT - RT - FT - KE = WT
Kinetic energy is the amount of warmth provided by kneading. As sourdough is typically kneaded for a short period, the kinetic energy value is lower than in yeasted bread. This value can be adjusted to suit your technique by investigating your results and comparing them to the temperature expected. If the final dough temperature is above the expected, reduce the kinetic energy value, and increase it if the final temperature is lower. See the full Desired Dough Temperature article to learn more.
If your proofing area is especially hot or colder than your desired proofing temperature the desired dough temperature can be adjusted to help it ferment. This will, of course, only be temporary as the dough will adjust to the climate of its surrounding area, but can be a helpful trick to use.
For example. If the proofing area is 40C (104F), and you want to proof at 32C (90F), you could adjust your desired do temperature to 20C (68F). This will mean your dough will proof below 32C (90F) for half the proofing time, and above it for the second half. This is by no means an exact science, the best way is to control the temperature of the proofing area.
The perfect temperature for sourdough is around 37C. This temperature is where lactic acid bacteria and yeast strains operate best. Yet bakers tend to prefer to proof sourdough at cooler temperatures. A slower rise brings out more flavour and is more optimal for lactic acid, as opposed to acetic acids. Also, when bulk fermenting, cooler temperatures allow the gluten to develop as its maturity is not temperature dependant.
I prefer proofing sourdough at around 25C (77F). Below this, the enzyme “amylase” is less effective. Amylase is present in the flour and is necessary for breaking down its damaged starch. The simple sugars it provides are consumed by the yeasts and LAB to produce gas. Enzyme activity doubles with a 10C rise (18°F) in temperature.
Varying sourdough proofing temperatures not only alter the rate of fermentation but also changes the flavour of the bread. You can find out more in the how to change the flavour of sourdough post.
Water quantity affects the rate of the rise. Wetter, more viscous doughs are quicker to ferment, thus speeding up the proofing time.
Flour absorbs water in varying ways between brands. This will affect the viscosity of the dough and therefore the proofing time. As well as this, depending on the elastic properties of the flour used, different doughs have the capacity to rise higher than others. This makes some flours unsuitable for long fermentations as they quickly weaken and collapse. See choosing the ingredients to make bread.
A sourdough starter is a fantastic collection of cultivated bacteria and wild yeasts. The collection one contains is reliant on the particles found in the flour, water and the local environment. The potency and vibrancy of the LAB and yeasts cultivated are heavily related to how you keep your starter. How old it is, how often it is fed, whether it has been starved recently and the temperature it is kept all have an impact on how quickly your bread will rise.
The variability of a starter makes sourdough baking much more complicated than yeast bread. See my sourdough starter troubleshooting guide to learn about improving the activity of your starter.
The amount of microbiological activity in your water affects the rate at which yeasts and organic acids can grow. Low activity in your water slows down the rate of growth, this can be great for keeping the bread fresh after baking, but it can slow things down during its production. Read Bakerpedia’s water activity guide to learn more.
Kneading and stretch & folds develop the gluten and add kinetic energy to warm the dough up. The more the dough is agitated, and the more effective the techniques used are, the more developed the dough will be. Lots of kneading and/or stretch & folds means a warm first rise is required to maintain an even gluten development vs gas production balance. More on this in a moment.
Salt inhibits the growth of the levain. This means increasing the amount of salt in a dough will slow down the rate of the rise. If you want to increase the amount of salt used in a recipe, expect it to take longer to proof. It’s imperative that salt isn’t added “to taste” when making bread. Salt serves many more functions than flavour so should be weighed before adding to the recipe.
An increase in humidity can be a very significant variable that causes unwelcomed results in your bread. Carbon dioxide is produced faster which can force the gluten structure to rupture. Bakers operating at high altitudes will likely find that their dough develops quicker than people like me who see the sea out of their window. If you are in high humidity or altitude you should be using less starter in your bread. A recipe that contains 10% starter to the total flour used is a good place to start.