Grain & dough ferment
Sourdough starter
Flour and water fed daily until wild yeasts and lactic bacteria make it rise reliably.
- Temperature
- 21–27 °C
- Cooler kitchens take longer.
- Time
- 7–14 days to become reliable
- Then indefinitely with regular feeding.
Timeline
Stage 1: Mix & feed dailystart · about 4 days
Fermenting / waiting — Early burst then quiet
Stage 2: Establishingfrom 4 days · about 6 days
Fermenting / waiting — Keep feeding at 21–27 °C
Stage 3: Reliable: doubles in 4–8 hfrom 10 days · keeps about 4 weeks
Cold storage — Fridge, feed weekly
Ingredients
- Wholegrain rye or wholewheat flour to start; bread flour later
- Water (chlorine-free if possible)
Equipment
- Glass jar
- Kitchen scale
- Rubber band to mark the level
Steps
- Day 1: mix 50 g wholegrain flour + 50 g water; cover loosely.
- Every 24 hours: discard all but 50 g, feed 50 g flour + 50 g water.
- Around days 3–5 it may rise then go quiet — normal; keep feeding.
- When it reliably doubles within 4–8 hours of feeding (often days 7–14), it's ready.
- Store in the fridge between bakes; feed weekly.
Is it working?
- Doubles within 4–8 hours of a feed
- Domed, bubbly, smells yeasty and pleasantly sour
- A spoonful floats in water (rough guide)
Smell & texture: Yeasty, sour, sometimes like yoghurt or apples; nail-polish smell means hungry — feed it.
Signs tell you it's fermenting, not that it's safe: never rely on smell or appearance alone.
Safety, mould and discard rules
Mould or yeast?
A grey or dark liquid layer ('hooch') is alcohol from a hungry starter — pour off or stir in and feed. Pink/orange streaks or fuzzy mould mean contamination: discard the whole jar and start again.
Storage
Fridge between bakes; feed at least weekly. Dried starter keeps for months.
Shelf life: Indefinite with feeding.
The science: what's happening
Wild yeasts and lactic acid bacteria from flour and the environment grow as you feed. Early activity is often other bacteria; after about a week the acid-tolerant yeasts and lactobacilli dominate, and the starter rises predictably after each feed.
Organisms
- Wild yeasts (e.g. Saccharomyces cerevisiae, Kazachstania humilis)
- Lactic acid bacteria (e.g. Fructilactobacillus sanfranciscensis)
Troubleshooting
- No activity after day 4
- Normal lull; keep feeding with wholegrain flour somewhere warmer (24–26 °C).
- Smells of acetone
- Hungry — feed more often or at a higher ratio (1:5:5).
A dish (not a ferment) gone wrong? Try Recipe Rescue.
Cook with it
Learn more
Sources
- Potential Hazards with Fermented Foods — Association of Food and Drug Officials
Guidance changes: check the source for current wording. Original text; figures quoted from the sources where stated.