Flavour & Fire
The Sourdough Journal
What Is Sourdough?
Sourdough is bread that rises through fermentation with a living culture of wild yeasts and lactic acid bacteria, rather than through added commercial baker’s yeast.
It may sound more complicated than it is.
At its heart, sourdough begins with flour, water and time. From that simple combination comes a starter: a living culture that you feed, care for and eventually use to ferment your dough. From that point on, baking bread becomes something more than mixing ingredients and waiting for the oven to do its work.
The dough responds to what you do. And to what you don’t do.
The Basics in One Sentence
If you reduce sourdough to its essence, it is actually quite simple: you use a living fermentation culture to make your dough rise.
Inside that starter, wild yeasts and lactic acid bacteria live together. The yeasts produce carbon dioxide, allowing the dough to rise. The lactic acid bacteria produce acids and other compounds that contribute to flavour and aroma.
It all happens at once, mostly without you seeing much of it.
You mix flour and water. You feed your starter. You give the dough time. And meanwhile, a great deal is happening.
What Makes It Different from Ordinary Bread?
Many everyday breads are made with commercial baker’s yeast. This yeast has been selected and cultivated to make dough rise quickly and reliably. You add it, give the dough time to rise, and usually have a fairly good idea of what to expect.
Sourdough is different.
Its leavening comes from a living culture that is constantly changing. Temperature, flour, water, the condition of your starter and the amount of time you give the dough all influence the result. Because of that, sourdough does not always fit neatly into a schedule.
Two loaves can be made from the same recipe and still turn out differently. Not because the recipe was wrong, but because the dough tells its own story along the way.
What Happens During Fermentation?
Most of the sourdough process takes place while it seems as though you are doing very little.
In your starter, and later in your dough, microorganisms use nutrients from the flour. The wild yeasts produce carbon dioxide, which becomes trapped in the dough and causes it to rise. The lactic acid bacteria produce acids and other compounds that gradually shape the character of the dough.
At the same time, the structure of the dough is changing. Enzymes break down certain components, gluten develops, and as fermentation continues the dough changes in composition, aroma and feel.
It is no longer a mixture simply sitting there.
It is a process.
For those who want to go deeper, the full explanation comes later in Understanding Fermentation, within Bread Science.
WhAnd What About the Starter?
The starter may be the most recognisable part of sourdough, but it is not the bread itself. It is the living culture you use to make the bread.
You begin with flour and water, creating the conditions in which wild yeasts and lactic acid bacteria can develop. By keeping part of your starter and feeding it fresh flour and water regularly, you keep that culture active. Over time, you learn to recognise it.
You see when it wakes up, when it reaches its peak and when it begins to fall again. You learn how it responds to warmth and cold, to different flours and to the amount of food you give it. Before long, a starter becomes more than a jar on the kitchen counter. It becomes part of the way you bake.
Why Is It Called Sourdough?
The name refers to the acids produced during fermentation.
These acids give sourdough its characteristic flavour, but that does not mean every sourdough loaf has to be sharply sour. A well-fermented loaf can be remarkably mild, with fresh, yoghurt-like notes and a depth of flavour that goes far beyond simply being “sour”.
How that flavour develops depends on many things: the starter, the flour, temperature, fermentation time and the way you handle the dough.
Sourdough does not have one fixed flavour.
That is part of its beauty.
Sourdough Is Not an Extra Ingredient
Perhaps this is the simplest difference to remember. You do not buy a packet of sourdough and add it to your dough. You maintain a living culture and use part of it when you bake.
Flour and water are the foundation. The microorganisms do the fermenting. Time and temperature largely shape how that process unfolds. You do not need to control every part of it. You simply need to create the right conditions and learn to pay attention to what happens next.
And perhaps that is the greatest difference from baking bread according to a strict schedule. With sourdough, you learn less to follow the clock and more to read the dough.
What You Can Do NowThe EssenceWhat You Can Do Now
Sourdough is not simply bread without commercial yeast. It is bread that rises through a living fermentation culture of wild yeasts and lactic acid bacteria. A culture you can build yourself, feed and maintain.
You begin with flour and water. Then you add time. And somewhere between those three things, something emerges that becomes more than the sum of its parts: a starter that lives, a dough that changes, and eventually a loaf that comes from your own oven.
That is sourdough.
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What Is Sourdough?
Two ingredients, one patient process, and bread that owes nothing to a packet of yeast.