NB: Above photo is from Boudin’s in San Francisco – they are near Fisherman’s Wharf (Pier 39) Boudin San Francisco Sourdough.
Sourdough, unlike many other types of dough, does not use shorter-term leavinings like packaged yeast, baking powder or banking soda (bicarbonate of soda to you, UK and others!). Instead, it garners yeast spores present on the flour to cause the dough/batter to rise; but first this yeast must be activated.
For those of you interested in the science, a very brief explanation is that yeast is all around us, in the air, on flour, on work surfaces, you pretty much name it. Another substance that is fairly omnipresent is lactobacilli; this substance when activated by mixing flour with water, breaks down the flour’s carbohydrates into sugars. And, as anyone has ever experienced when baking yeast doughs, sugar is what yeast feed on to multiply. And, the end product (yes, waste product) of yeast is carbon dioxide (CO2) the bubbles of which provide the “rise” for a dough/batter when it is trapped by gluten in the flour.
This means that the starter must be prepared in advance to allow the necessary substances to be: a) attracted to and activated in the starter mixture (or “culture”); and b) allow the yeast to multiply and release all that lovely CO2.
Just to push this lesson one step further, the conditions at which you keep your starter during the time it’s fed, as well as the temperature at which you allow your sourdough bread to rise, affect the end flavour of the bread (or batter, for that matter). Without going too into depth for now, allowing the culture to ferment and dough to rise at cooler temperatures (50F or 10C) will result in a tangier, more sour-tasting result (bring it on!), and allowing the starter and bread to ferment/rise in a warmer temperat’ure will producer a richer, mellower loaf. For a more detailed explanation, look here:
King Arthur Flour Sourdough Guide: King Arthur Flour Sourdough Guide
The recipe I list here is one type of sourdough starter – there are plenty of types out there. Some use just all purpose flour, some use a combination of all purpose and rye flours, etc. And of course some cooking retailers will sell you ready-made starter that you can use in about 24 hours (see: King Arthur Sourdough Starter).
Ingredients needed: wholegrain flour, water, all-purpose flour (for feeding), non-reacting container (crockery, glass, stainless steel, food-grade plastic)
Immediate time required: 5-10 minutes (for beginning), 3-5 minutes (for feeding)
Overall time required: How much have you got? (actually to start, about 1 week, unless using pre-made starter)
NB: I am providing a version of the recipe in each of volume, ounces and grams. If you pick one, please don’t switch to another version as this could ruin the recipe.
1 cup ( 4 oz , 113 g) rye or wholewheat flour
1/2 c ( 4 oz, 113 g) non-chlorinated water
1 c ( 4 oz, 120 g)all-purpose flour
1/2 c ( 4 oz, 113 g) cool water (if surroundings warm) or lukewarm (if surroundings are cool)
- Day 1: Combine rye/wholewheat flour with the cool water in container.
- Stir thoroughly so no dry flour remains; cover container loosely and let mixture sit at about 70°F for 24 hours
- Day 2: Whether you see no activity of a bit of bubbling, discard half the starter (4 ounces, about 1/2 cup)*, and add to the remainder a scant 1 cup all-purpose flour, and 1/2 cup water (as listed above).
- Mix well, cover, and let the mixture rest at room temperature for a day.
- Day 3: You should now see some activity — the mixture should have expanded, and be bubbly with a fruity aroma. Now comes the dedication: for today, it’s two feedings, as evenly spaced as possible (and see step 8). Each time you do a feeding, measure out 4 oz starter (about 1/2 c when stirred down); discard remainder*.
- Add a scant 1 c (4 oz) all-purpose flour, and 1/2 cup water to the 4 ounces starter. Mix the starter, flour, and water, cover, and let the mixture rest at room temperature for approximately 12 hours before repeating.
- Day 4: Weigh out 4 ounces starter, and discard any remaining starter*. Repeat step #6.
- Day 5: Weigh out 4 ounces starter, and discard any remaining starter*. Repeat step #6. By the end of this day, the starter should have at least doubled in volume. There’ll be lots of bubbles; there may be some little “rivulets” on the surface, full of finer bubbles. The starter should have a tangy aroma that is not overpowering. If your starter hasn’t risen much and isn’t showing lots of bubbles, repeat discarding* and feeding every 12 hours on day 6, and day 7, and as long as it takes to create a vigorous (risen, bubbly) starter. Note that the important thing is to reach the stage where the starter doubles in volume about 1-4 hours afer feeding; this may take more than 7 days, even up to 21 days!.
- Once the starter is ready, give it one last feeding. Discard all but 4 ounces (a generous 1/2 cup)*. Feed as usual. Let the starter rest at room temperature for 6 to 8 hours; it should be active, with bubbles breaking the surface.
- Remove however much starter you need for your recipe (no more than 8 ounces, about 1 cup); and transfer the remaining 4 ounces of starter to its permanent home: a crock, jar, or whatever you’d like to store it in long-term. Feed this reserved starter with 1 cup of flour and 1/2 cup water, and let it rest at room temperature for several hours, to get going, before refrigerating it.
- Store this starter in the refrigerator, and feed it regularly; we recommend feeding it with a scant 1 cup flour and 1/2 cup water once a week.
*NB: Just because you’re “discarding” the remainder doesn’t mean it needs to go to waste: it can be used for sourdough pancakes and waffles (so good!) as well as other recipes. I’ll post some to the site soon, but you can always find them on the (you guessed it!) – internet!