Troubleshooting
Almost everything alarming about a sourdough starter is normal. Here is the short list of what is fine, and the much shorter list of what is not.
Throw it away only if…
- There is fuzzy mould - white, green, black or blue fur, with texture. Flat white film is not mould, fur is.
- There are pink, orange or red streaks, which indicate bacteria you do not want.
- It smells genuinely putrid or rotten rather than sharp and sour.
In those cases discard the whole lot, wash the jar in hot soapy water, and start again with fresh flakes. Do not try to scrape mould off and rescue the rest.
Normal things that look wrong
A layer of dark liquid on top
This is hooch, and it means your starter is hungry. It is alcohol produced when the yeast runs out of food. Either pour it off (milder result) or stir it back in (more sour result), then feed. If it keeps appearing, feed more often or use a bigger feeding ratio.
It smells of nail polish remover or solvent
Also hunger. Acetone notes are a classic sign of an underfed starter. Feed it at 1:3:3 or 1:5:5 for a couple of days and the smell will settle into something more like yoghurt.
It smells of old socks, cheese or vomit
Very common in the first few days of a revival, when the bacterial population has not settled yet. Keep feeding on schedule. It almost always resolves by the end of the first week.
It rose beautifully once and then never again
The first dramatic rise in a new starter is usually produced by a bacterium that then dies off, not by yeast. It is a false start and everyone falls for it. Carry on feeding; the real, repeatable rise arrives a few days later.
It sank
That is the normal cycle. It rises to a peak, runs out of food, and falls. You simply missed the peak. Feed it, and next time watch a bit earlier.
It is runny rather than thick
That is hydration and flour, not illness. A wetter starter is looser and ferments more actively. If you want it thicker, use a little less water at the next feed, or a flour that absorbs more.
The bubbles are small
Fine. Bubble size reflects the flour more than the health of the culture - strong white flour gives big showy bubbles, wholegrain gives lots of small ones. Judge by the rise.
It has bubbles but will not actually rise
Different problem, and a real one. A healthy starter should double or triple within 8-12 hours. If it is bubbling but staying flat, reset it: feed at 1:5:5 with warm water, in a warm spot, for a few days running.
Do I have to catch it exactly at peak?
No. At peak it is at its strongest and gives the best rise. A younger starter gives a milder flavour; one that has just started to fall gives a more sour loaf. All three make bread.
Speeding it up or slowing it down
Temperature does most of the work, with the amount of starter as a second lever.
| To go faster | To go slower |
|---|---|
| Warmer water when mixing or feeding | Cooler water |
| A warm spot - oven with just the light on | The fridge |
| More starter in the recipe | Less starter in the recipe |
Nothing is happening at all
Work through these in order.
- Is it warm enough? This is the cause roughly half the time. Below about 20 °C everything crawls. Move it somewhere warmer, such as an oven with just the light on.
- Is your water chlorinated? Chlorine and chloramine suppress the culture. Use filtered or bottled water, or leave tap water out overnight.
- Is your flour bleached? Bleached flour is a poor food source. Switch to unbleached bread flour.
- Give it a wholegrain boost. Replace about a fifth of the flour in one feed with wholemeal or rye. Those flours carry far more wild yeast and minerals and often restart a stalled culture within a day.
- Give it more time. Ten days is not unusual for dried flakes, especially in a cool kitchen.
Bread problems that are actually starter problems
| Symptom | Likely cause |
|---|---|
| Dense, gummy, barely risen loaf | Starter was not at its peak, or not yet strong enough. Keep feeding for another week before baking again. |
| Dough spread flat instead of rising | Over-fermented. Shorter bulk ferment, or a cooler spot. |
| Far too sour | Feed more often, use a larger ratio, and keep the dough cooler. |
| No sourness at all | Let the dough ferment longer, or retard it in the fridge overnight. |
Bread problems that are just bread problems
| Symptom | Likely cause |
|---|---|
| Gummy crumb | Underbaked, sliced too early, too much water, or an immature starter. Bake to 96-99 °C inside and cool it for two hours. |
| Burnt bottom | Too much heat from below. Put a baking tray on the shelf underneath, or sit the pot on a layer of uncooked rice or a stone. |
| Loaf burst open at the side | Not scored deeply enough, so the steam found its own way out. |
| Blade dragged, dough deflated as you cut | Dough was warm, or over-proofed. Score it straight from the fridge. |
| Thick dry skin that cracked oddly | Dough dried out during the final proof. Cover the banneton properly. |
| No Dutch oven at all | Any oven-safe dish with a lid works. Two loaf tins clamped together, or a loaf tin covered tightly with foil, will do the job. |
Flour and water questions
- Organic flour? Not necessary. Unbleached and unbromated is what matters.
- Tap water? Usually fine. Chlorine does interfere, so if yours is heavily treated, filter it or leave it out uncovered for 24 hours.
- Gluten-free flour? Possible, but it behaves nothing like wheat. Use a recipe written specifically for gluten-free sourdough rather than adapting this one.
The general rule
If you are unsure, feed it and wait. Starters are far more often under-fed than over-fed, and the fix for almost everything is a fresh feed in a warm spot.
Something not covered here? Ask me - and send a photo, it helps enormously.