Sourdough starter from scratch in 7 days
Sourdough starter from scratch in 7 days: wholemeal and white flour, chlorine-free water, daily feedings, the float test and how to keep it in the fridge.
What a sourdough starter is and what it is for
A sourdough starter is a natural culture of flour and water in which wild yeasts and lactic bacteria live: the leaven that makes bread rise without commercial yeast and gives it its slightly sour flavour and thick crust. You create it from scratch in a week, mixing wholemeal flour with water on the first day and feeding it daily with equal parts white flour and water; from day 7, if it doubles in volume in 4–6 hours and floats, it is ready to bake with. It lives in a glass jar and, once active, keeps in the fridge with one feeding a week. It is the base ingredient of sourdough bread, which calls for 100 g of active, bubbly starter.
Ingredients
Instructions
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Day 1
Mix wholemeal flour and water
Weigh 50 g of wholemeal wheat or rye flour into the clean jar and add 50 ml of chlorine-free water at 25–28 °C. Stir with a spoon until you have a thick paste with no dry lumps, like porridge. Wipe the sides of the jar, rest the lid on top without sealing it so air can get in and gases can escape, and leave it for 24 hours somewhere at 22–26 °C, away from direct sun and draughts. Mark the starting level with a rubber band around the jar.
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Days 2 and 3
Feed for the first time (day 2)
On the second day there may be a few small bubbles and a sweet or wet-flour smell; seeing nothing yet is also normal. Without discarding anything, add 50 g of wheat flour and 50 ml of water at 25–28 °C, stir until combined, wipe the sides and rest the lid on top again without sealing. Another 24 hours at 22–26 °C.
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Discard half and feed (day 3)
Today the discards begin. Remove and throw away half of the mixture (keep about 100 g) and add 50 g of wheat flour and 50 ml of water. This is usually the most active day: the mixture can rise a lot and smell strong, of overripe fruit or vinegar. It is a burst of bacteria that calms down afterwards; it does not mean the starter is ready. Stir, wipe the sides, rest the lid on top and wait 24 hours.
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Days 4 to 6
Feed every 24 hours
Every day, at the same time, leave only 50 g of starter in the jar, discard the rest and add 50 g of wheat flour and 50 ml of water (a 1:1:1 ratio). Move the rubber band to the new level so you can see how much it rises over the following hours. If your kitchen is warmer than 26 °C, feed every 12 hours with the same amounts. Between days 4 and 5 it is normal for the starter to seem asleep after the burst of day 3: keep feeding it at the same rhythm.
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Ferment and read the signs
Around days 5 and 6 the starter finds its rhythm: it rises steadily in the hours after each feeding, fills with bubbles of every size and smells of yoghurt or mild vinegar. A smell of acetone or nail-polish remover means it is hungry: feed it every 12 hours for a day. A greyish liquid on top is the same signal; stir it in or pour it off and feed. Only mould (green, black or pink fuzz) means you must throw it away and start again.
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Day 7
Do the float test
Feed as usual and watch the next 4–6 hours: the starter is ready if it doubles in volume in that time, with a domed surface full of bubbles. Confirm with the float test: a teaspoon of starter dropped into a glass of water should float. If it doubles and floats, you can now use the 100 g the sourdough bread recipe calls for. If it still rises only a little, it is not a failure: keep feeding for 2 or 3 more days at the same rhythm and repeat the test.
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Maintenance
Store in the fridge
Once it is active, move it to a clean jar with the lid closed and keep it in the fridge. There it works very slowly: one feeding a week is enough (leave 50 g, add 50 g of flour and 50 ml of water, wait 1–2 hours at room temperature and chill it again). If you are going to bake, take it out the day before and give it two feedings 8–12 hours apart so it regains its strength.
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Weigh out 100 g for the bread
Weigh out the 100 g of active starter the sourdough bread recipe calls for right when it is at its peak after a feeding, 4 to 6 hours later. Always leave at least 50 g in the jar and feed them so you never run out of starter. The daily discard can go into pancakes, savoury crackers or the dough of a quick bread. A well-kept starter lasts for years; if you see mould or a pink tinge, throw it away and start another.
Foodtastico Tip
If you are not baking for several days, keep the active starter in the fridge with the lid on and feed it once a week. To use it again, take it out the day before, give it two feedings 8–12 hours apart and wait until it doubles.
Nutrition information
| Calories | 80 kcal |
|---|---|
| Protein | 3 g |
| Carbs | 16 g |
| Sugars | 0 g |
| Fat | 0 g |
| Trans fat | 0 g |
Values per serving (1 of 4).
Frequently asked questions
Which flour is best for starting a sourdough starter?
For the first day, wholemeal wheat or rye flour: it keeps the outer layers of the grain, where there are more wild yeasts and minerals, so it gets going faster. From day 2 you feed it with plain wheat flour, which gives a cleaner, more predictable starter; strong flour is not necessary for the starter itself, although it does help in the bread. Avoid self-raising flour.
Why is my sourdough starter not rising?
The most common causes are cold (below 20 °C everything runs at half speed), chlorinated water, infrequent feedings or a very refined flour. Find a spot at 22–26 °C, use filtered water or water that has been boiled and cooled, and keep up the daily feeding. A pause between days 4 and 5, after the strong activity of day 3, is normal: keep feeding and it usually wakes up within two or three days.
Why does it smell of acetone or nail-polish remover?
That smell is alcohol and acids building up when the starter has gone too many hours without food. It is not spoiled: feed it every 12 hours for a day or two, leaving only 50 g and adding 50 g of flour and 50 ml of water, and the smell goes back to yoghurt or mild vinegar.
What is the dark liquid that appears on top?
It is a layer of alcohol and water that separates when the starter is hungry, grey or light brown in colour. It is not dangerous. You can stir it back in (for a more sour flavour) or pour it off with a spoon, then feed as usual. If it appears every day, shorten the gap between feedings to 12 hours.
Can I use tap water?
It depends on the chlorine: in high amounts it slows down the yeasts and bacteria. The safe options are filtered water, or tap water boiled and cooled to 25–28 °C; leaving the water in an uncovered glass for an hour so the chlorine evaporates also works. Still mineral water works just as well.
How long does it take for the starter to be ready?
At 22–26 °C, about 7 days following this recipe. In winter or in a cold kitchen it may need 10 to 14 days: do not change the method, just give it more time and, if you can, move it closer to a gentle source of warmth. What tells you it is ready is not the calendar but that it doubles in volume within 4–6 hours of a feeding and passes the float test.
How do I know I can use it for sourdough bread?
When it doubles within 4–6 hours of a feeding and a teaspoon of it floats in a glass of water. Use it at that moment, at its peak and before it starts to fall: that is when it has the most strength to lift the 500 g of flour in the sourdough bread recipe, which calls for 100 g of active, bubbly starter.
What do I do with the daily discard?
You do not have to throw it away. Keep it in a container in the fridge for up to a week and use it in doughs that do not need to rise on their own: pancakes, savoury crackers, pizza dough or a quick bread made with baking powder. It adds a sour note and uses up the flour that would otherwise be wasted every day.
What if mould appears?
If you see green, black or hairy white fuzz, or a pink or orange tinge, throw it away and start again with a clean jar: it cannot be rescued. To prevent it, wipe the sides of the jar at every feeding, use clean utensils and never leave the starter more than two days without food at room temperature.
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