How to Make a Sourdough Starter: Everything You Need to Know Starter Guide
Sourdough begins through spontaneous fermentation—essentially by getting your wheat wet! All you need to start a batch—and to keep it alive and bubbling—is flour and water. The most important consideration when keeping a sourdough starter is that it must be fed regularly. And this reliably fermenting starter can now be used to bake your daily bread.
The following excerpt is from Milk Into Cheese by David Asher. It has been adapted for the web.
Sourdough Starter
The philosophy of sourdough deserves its place in these pages for numerous reasons.
Sourdough is a medium that helps the development of an important cheese rind ecology. For Penicillium roqueforti, the fungus responsible for blue cheeses’ evolution, grows upon sourdough bread.
Milk is meant to ferment; it can develop into an effective starter culture known as clabber simply with its inherent microbiology. PHOTO COURTESY OF MAX JONES
Sourdough in its handling is very similar to dairy cultures such as kefir, and almost identical to clabber. For many readers, sourdough is likely the first fermentation they encountered, and one that can help them understand how dairy fermentation works. I often turn to sourdough fermentation for inspiration in my cheesemaking, having first understood how natural fermentation functions through its care.
Sourdough is also the medium in which natural fermentation is most evolved and universal. Its prevalence lends credence to the idea that natural methods in cheesemaking work. I find great hope that natural methods can be more readily practiced and adopted thanks to the growth that sourdough is experiencing and has been experiencing for decades. It’s certainly a gateway fermentation, and one that has helped many gain a taste for creating a deeper connection to how they feed themselves, their families, and their communities.
Comparison of Sourdough and “Sourmilk”
There are significant parallels between the forms of fermentation in sourdough and in dairy that aren’t often discussed. These may well be the same microbiological phenomenon.
Both sourdough and clabber / kefir feature two phase fermentations. In both media this begins with a bacterial breakdown of complex sugars—either starches or lactose—into lactic acid (the origin of the sour in sourdough, as well as the sour in kefir and clabber). The lactic acid is then fermented by a yeasty or fungal fermentation into alcohol, carbon dioxide, and other metabolic by-products.
It may well be that the community of yeasts that cause sourdough bread to rise is the same community of microbes that establish white rinds on cheeses. Both cultures feature abundant lactic acid that supports the fermentation of yeasts; and both feature the growth of white surface yeasts that feast upon the ferment’s abundant lactic acid. It’s common for sourdough bread bakers to report the growth of white-film yeasts atop a long-neglected sourdough starter left at room temperature— this may be equivalent or even identical to the film yeasts that grow atop long-neglected kefir and clabber cultures.
When a kefir or clabber, with its abundant yeasts, is mixed into flour to form a dough, that dough will rise, like sourdough within 12 hours, and can be baked into a delicious bread. That dough can also be re-fermented like sourdough and become an effective sourdough starter culture more or less immediately, with no lag time. Equivalently, a sourdough starter can be used to begin a clabber culture, by adding a small amount of an active sourdough culture to milk. From what I’ve come to understand, they’re more or less the same microbiological phenomenon.
Similarly, cheese can be made to go yeasty, rising like a loaf of sourdough, even featuring aromas reminiscent of bread and beer—as is the case in ambarees and aging lactic cheeses. Equivalent fermentations can even cause milk to develop a strong alcoholic character from the metabolisms of lactose to alcohol, as in my recipes for milkbeer and amasi.
This tendency of cheese to go yeasty is not a contamination as many believe. Many swear that sourdough bread and cheese should be kept in separate kitchens. Instead, such a yeastiness is an evolution of the yeast ecologies that are a part of milk’s complex community. And the ways in which these yeasts can be encouraged are equivalent in cheese and bread and even wine!
Starting a Sourdough
A well-managed sourdough starter showing good gas development. Unlike with kefir or clabber or most styles of cheese, such yeastiness is desirable. However, the yeast development in sourdough may be the same microbiological development of some cheese rinds.
Sourdough bakers always add a starter to their batches of bread. But how does that starter itself start? A clabber culture is begun by spontaneously fermenting milk, and you can similarly begin a sourdough through spontaneous fermentation—essentially by getting your wheat wet!
A sourdough starter can be started from scratch by getting flour wet and initiating its inherent tendency to ferment. It is best to source a natural flour, preferably whole wheat (or rye) and preferably stone ground, so as not to be submitted to the high temperatures of typical processing that essentially pasteurize the flour.
Add enough water (preferably unchlorinated) to 1 cup flour to make a paste—not too wet, not too dry. Leave this mixture in a jar with a loose-fitting lid or cloth covering (avoid metal, as it will rust over time— clay pots are often preferred by bakers for this reason) at room temperature (preferably 20°C [68°F]) for 2 to 3 days, until it bubbles. Interestingly, the speed and quality of this first fermentation can be improved by adding clabber or kefir in place of water as they share many microbes in common.
Once this first ferment is bubbling, refresh it with fresh flour. Take a small amount of this starter (1 tablespoon) and place it in a fresh jar (discard the remaining first ferment in the compost). Add fresh flour (1/2 cup) and enough water to make a dry paste; this constitutes the first feeding of the ferment. Now that a seed of starter was added, this second fermentation will proceed much faster, typically becoming bubbly in 12 to 24 hours.
Once this second ferment is bubbling, refresh again with fresh flour: Take a tablespoon of the ferment, add 1/2 cup of flour, and add enough water to make that paste. This daily rhythm can now be repeated, refreshing the starter in the morning with a tablespoon of the starter. Within 6 to 12 hours the ferment will be bubbly and ready to use for baking its first sourdough loaf.
Keeping a Sourdough
The most important consideration when keeping a sourdough starter is that it must be fed regularly to maintain its effectiveness. This regular, rhythmic feeding now conserves the best community of flour fermenting microbes and will create as perfect a loaf as possible, with a strong rise in the right amount of time, and no off flavors. Keeping this culture reliably fed will keep it peaking within 6 to 12 hours daily, over and over and over. And this reliably fermenting starter can now be used to bake your daily bread.
The excess starter (made with about 1/2 cup flour) from each daily feeding will suffice as a starter to bake a medium-sized loaf of bread daily with around 3 cups flour (a 1:6 ratio, as below).
Or the steady starter can be preserved in its active state for up to 1 week in the fridge between feedings. If neglected longer, it will have to be refreshed once or twice before it is bubbly in 6 to 12 hours and ready to bake again.
In warmer weather (30°C [86°F]) a starter will have to be fed twice daily (at least) to keep in its finest form. The ferment will rise in less than 6 hours and will lose its peak fermentation after 12 hours.
Quantity Matters
When baking with sourdough, the second most important consideration is the ratio of starter culture to dough.
For years I failed in my sourdough baking because I added starter to my dough in the same ratio as my cheesemaking— 1 part starter to 50 parts dough. Little did I know, but my sourdough style had devolved over the years into my cheesemaking style, and whenever I struck out to master my bread baking again, I’d always fall into this trap, adding too little starter and failing to successfully rise my loaves.
It was only in recent years, more than a decade after I’d started baking sourdough and had been fully distracted by cheesemaking, that I rediscovered why my sourdough had failed to raise my breads for so long: I wasn’t adding enough starter. My doughs fermented too lactic and failed to develop almost any yeast fermentation at all.
The reason for this was fully related to the ratio of starter I added. I spoke with a professional baker, who told me that the ratio of starter to dough that he used in nearly all of his bakes was about 1:6, or 1/2 cup starter to 3 cups flour. It turns out that 1:50 compared with 1:6 makes a world of difference to the ecology of a bread and its balance of bacterial and yeast fermentation.
However, when a larger proportion of starter is added to a dough, larger populations of both bacteria and yeasts are added, both of which now can effectively ferment the dough in a more balanced manner. The yeasts have less growing to do to ferment that dough, so both the bacteria and yeasts ferment more equally. And such a bread features a pleasing and flavorful sourness (if fermented the right amount of time), the right amount of rise, and a good breakdown of the flour, resulting in greater digestibility.
However, when an even larger enough amount of ripe starter is added, a large amount of lactic acid is added directly to the dough, enabling the yeasts to develop and the bread to rise without any fermentation of the freshly added flour at all!
This occurs when you add starter to dough in a ratio of 1:2—a bread prepared with 3 cups flour, 11/2 cups of which were in the prepared starter. A bread baked this way presents almost no sour notes or flavors at all, and the yeasts take off and cause the bread to rise almost immediately as the dough is already supplied with its favorite food, lactic acid.
In essence, a 1:2 dough isn’t fermented, and the bread itself rises fully with the activity and ingredients in the starter instead of the starters’ fermentation of the added flour in the dough. The paste of such a bread remains un-broken-down, showing the bran flakes distinct from the starch in a whole wheat loaf (similar to the appearance of a whole wheat bread prepared with a sweet starter). In a 1:6 dough, however, the bran breaks down due to a more significant fermentation and acidification of the dough. And in a 1:50 dough, there’s a complete bacterial fermentation of the dough before almost any yeast development occurs at all.
Certain types of bread are made with different balances of yeast and bacterial fermentation. The same is true with cheese. Some styles of cheese need to be heavy on the bacterial fermentation and light on the yeast to avoid being overwhelmed by unwanted yeasty effects in cheese. Most styles, however—especially naturally rinded cheeses—need some yeast development in order to develop their best rinds (we add starter culture in a ratio of 1:50 to 1:100 for these). Some very special dairy ferments like milkbeer and Lebanese ambarees need to have even stronger yeasty fermentations in order to develop their most appropriate character (we add starter in a ratio of 1:10 for these).