Sourdough discard is the portion of starter you'd normally throw away before feeding. It's still living dough — just hungry — and it adds tang, structure, and a small leavening boost to recipes from pancakes to pizza. The trick is matching the age of your discard to the bake. This guide walks through what you can do with sourdough discard today, what only old discard is good for, and the rare moment you should genuinely bin it.
What is sourdough discard?
Sourdough discard is the spoonful of starter you pour off before you feed the jar. It's still alive — just past its peak. Think of a starter at peak as a dough that's just risen: full of CO₂, smelling sweet. Discard is that same dough an hour or two later — collapsed, smelling tangier, the yeast tired. Both bake. The difference is what they bake.
Why we discard before feeding
Three reasons in plain language: (1) acidity control — without discarding, the lactobacilli would acidify the jar until they kill themselves; (2) volume control — feed daily without discard and you'd own 1.6 kg of starter by Friday; (3) flavour control — old, neglected starter ferments bread too aggressively.
And here's the lever: discarding isn't wasting if you bake with it. WRAP UK estimates the average household bins around £1,000 of avoidable food a year. Discard, used well, is one of those quietly avoidable bits.
What discard is made of (and what it isn't)
Discard is roughly half water, half flour, with a wild-yeast colony and a thriving population of lactobacilli (the bacteria that produce the tangy acids). It is not a leavener you can rely on — by the time it comes off the starter, the yeast has eaten most of the available sugar.
Is sourdough discard supposed to leaven?
Sourdough discard is not really supposed to leaven on its own. By the time you pull it off a mature starter, the wild yeast has eaten most of the available sugar and gone quiet. There's a small reserve of activity — enough to give pancakes a fluffier crumb and crackers a touch of lift — but you'll usually pair discard with baking powder, bicarb, or commercial yeast for any serious rise.
This is the single most-misunderstood thing about discard. People put it in bread expecting a rise and get a brick. Pair it with help.
Discard vs active starter — how to tell at a glance
Three sentences and a table. Look. Smell. Test. Then bake the right thing.
| Sign | Active starter | Sourdough discard |
|---|---|---|
| Appearance | Bubbly, domed, risen | Collapsed, flat, often with a thin layer of grey hooch on top |
| Smell | Sweet, yoghurty, faintly fruity | Tangy → vinegary as it ages |
| Float test | Floats in cold water | Sinks, mostly |
| Texture | Light, foamy, holds peaks briefly | Liquid, runny, falls off the spoon |
| Age since feed | 4–12 hours | 12+ hours, often days |
| Best use | Bread, levains, real loaves | Pancakes, crackers, pizza, savoury bakes |
What's the difference between sourdough starter and sourdough discard?
Sourdough discard is the portion of an active starter you remove before feeding it. They're the same mixture chemically — flour, water, wild yeast, lactobacilli — but discard has gone past its peak, so the yeast is exhausted and the acidity is higher. Active starter leavens bread on its own. Discard mostly flavours; it can lift batters slightly, but you'll usually pair it with baking powder.
The float test, and when it lies
The float test: a spoonful in a glass of cold water should float if the starter is active. Caveats: a very freshly-fed starter sometimes sinks because the yeast hasn't built gas yet; a discard with hooch on top sometimes floats briefly because trapped CO₂ hasn't escaped. The float test is useful, not gospel. Use the smell test alongside.
The smell test, day by day
Why does my sourdough discard smell vinegary?
Sourdough discard smells vinegary because the lactobacilli in it have been producing acetic acid faster than the yeast has been producing alcohol — usually a sign the discard is more than five days old, or that it has been stored a little too cold. It is not spoiled. Vinegary discard is perfect for savoury crackers, pizza dough, and rye-style breads where the tang is welcome.
The spectrum: day 0 sweet yoghurt → day 3 tart yoghurt → day 5 sharper → day 7 vinegary → day 10+ nail-polish-remover (acetone — the boozy phase). Acetone is the boundary — past that, smell tells you nothing useful, just bin.
How to save sourdough discard (the jar in the fridge)
Most UK kitchens already own the container they need. Here's the practical setup.
The container that works in a UK kitchen
UK-specific: a clean 500 ml Kilner-style jar with the rubber seal removed (or a jam jar with a square of greaseproof and an elastic band). NOT airtight — discard continues to produce small amounts of CO₂ in the fridge and a sealed jar can pop the lid off. (We cleaned discard off a ceiling once — Clara still mentions it.) Glass over plastic (plastic absorbs smells). Why not the original jar your starter lives in? Because mixing today's discard with last week's confuses the timeline. Each week, a fresh jar. Label with masking tape and the start date.
When to start a fresh jar
Once the jar's been open more than 14 days, start a new one. Don't add fresh discard to old. Don't be precious about it — composting is the right call once a jar's hit two weeks. Also: if you bake daily, you barely save up; if you bake weekly, you'll have 200–400 g by Friday. Cumulative volume matches your bake rhythm. (See the full discard storage timeline.)
Six things to make TODAY with fresh discard
Six quick options, with a UK swap noted where it matters. Links out to the deep-dive recipe articles where they exist.
Quick discard decision
Discard pancakes
The simplest use. 200 g discard, 100 g plain flour, 1 egg, 200 ml milk, 1 tsp bicarb, a pinch of salt. Light, fluffy, tangy. UK swap: bicarb not baking soda; plain flour not all-purpose. Full method: our discard pancake recipe.
Discard crackers
200 g discard + 30 g olive oil + salt + seeds, spread thin, baked at 160°C fan for 25 minutes. The kitchen smells incredible. Full method: the cracker recipe.
Discard pizza dough
300 g discard + 200 g strong white bread flour + 5 g salt + 100 ml water. Knead briefly, rest 1 hour, stretch onto a tray. The flavour is genuinely better than commercial pizza dough. UK swap: strong white bread flour (Allinson, Marriage's, Wessex Mill), not "bread flour" generic. Full method: Friday-night pizza dough.
Discard scones
Brilliant savoury or sweet — fold 100 g discard into a standard scone mix and reduce the liquid by 50 ml. Cheese-and-chive sourdough scones are Clara's Sunday afternoon thing. The discard lifts them and adds a faint tang that pairs beautifully with mature cheddar or Lancashire.
Discard waffles
Same batter as pancakes but with 2 tbsp melted butter folded in for crispness. Waffle iron, medium-high, 4 minutes each. The lactic tang cuts beautifully against maple syrup or golden syrup.
A no-knead loaf (with a little help)
Can I bake bread with sourdough discard?
Yes, you can bake bread with sourdough discard — but you'll need help. Discard on its own gives roughly 10–20% of the rise an active starter would, so most discard-bread recipes also add commercial yeast or baking powder. The exception is a long, slow overnight ferment: 200 g of fresh discard, 400 g strong white flour and 7 g salt left covered for 12 hours will rise enough for a respectable Dutch-oven loaf.
The recipe shape: 200 g discard, 400 g strong white bread flour, 7 g salt, 280 ml water, ¼ tsp instant yeast (the helper). Mix, cover, rest 12 hours, shape, bake in a Dutch oven at 230°C fan for 35 minutes. The crust is good. The crumb's tighter than a true sourdough loaf — but it's real bread, made from what was almost in the bin.
Discard bingo
Tick what you've tried. Most beginners hit five in a fortnight. The compost square is permission — it's not a failure.
Pancakes
Crackers
Pizza
Scones
Waffles
No-knead loaf
Dusting powder
Gift to a friend
Compost (it's fine)
Three things only old discard is good for
Once discard's past day five, the rules change. Older discard has more acetic acid, less yeast — the wrong ingredient for fluffy pancakes, but the exact right ingredient for these three.
Sharper crackers (the savoury, vinegary version)
Same crackers as above, but with day-7+ discard the tang becomes the headline. Add rosemary, sea salt, cracked black pepper. Excellent with a wedge of mature Cheddar or Cornish Yarg. The vinegary edge balances rich, fatty dairy — the bake equivalent of cornichons next to pâté.
A pre-ferment for tomorrow's pizza dough
Old discard refreshed with fresh flour and water becomes a poolish — a wet pre-ferment that boosts pizza dough's flavour without the time commitment of a full sourdough bake. 100 g old discard + 100 g strong white flour + 100 g water + a pinch of instant yeast → leave 8 hours covered on the worktop → use as half the flour weight in tomorrow's pizza dough. The result is bakery-grade.
Dehydrated starter dust (for scoring and dusting)
Spread a thin layer of old discard on greaseproof paper, dry in a 50°C oven (or on top of a warm radiator) for 6 hours, then grind to a powder with a pestle and mortar. Use to dust bannetons or sprinkle on loaves before scoring — for a crisp white pattern across the crust. It's a good one.
When you genuinely should bin it
None of the discard guides will tell you when to bin discard. We will. Most of the time, discard's fine. Sometimes it isn't, and you save yourself a stomach ache by knowing the difference. Honest beats clever every time.
The four red-flag signs
1. Pink, orange, or red streaks on the surface — almost certainly Serratia marcescens or another bacterial overgrowth. Bin. Wash the jar in hot water.
2. Fuzzy mould of any colour — white, blue, green, black. Fungal. Bin.
3. Acetone or kerosene smell with no yeast-y or yoghurty undertone — past the boozy phase. Bin.
4. A slick, slimy layer over the hooch (not just dark liquid — slimy) — bacterial spoilage. Bin.
None of this is dramatic, all of it is rare with proper fridge storage, and all of it is unambiguous. If you see any of the four, compost or bin. Start a new jar tomorrow.
Why the FSA says compost is safer than guesswork
The UK Food Standards Agency's guidance on fermented dough at home is conservative: when in doubt, don't eat it. Sourdough discard sits in a low-pH (acidic) environment that suppresses most pathogens if it stays at fridge temperature. Once a jar gets warm, or has been opened repeatedly with a contaminated spoon, the rules change. We follow the FSA line: visual check + smell check + age check every time. Three "yes"es or it goes in the compost.
Frequently asked questions
What's the difference between sourdough starter and discard?
Sourdough discard is the portion of an active starter you remove before feeding it. They're the same mixture chemically — flour, water, wild yeast, lactobacilli — but discard has gone past its peak, so the yeast is exhausted and the acidity is higher. Active starter leavens bread on its own. Discard mostly flavours; it can lift batters slightly, but you'll usually pair it with baking powder.
Can I bake bread with sourdough discard?
Yes — but you'll need help. Discard on its own gives roughly 10–20% of the rise an active starter would, so most discard-bread recipes also add commercial yeast or baking powder. The exception is a long, slow overnight ferment: 200 g of fresh discard, 400 g strong white flour and 7 g salt left covered for 12 hours will rise enough for a respectable Dutch-oven loaf.
Why does my sourdough discard smell vinegary?
Sourdough discard smells vinegary because the lactobacilli in it have been producing acetic acid faster than the yeast has been producing alcohol — usually a sign the discard is more than five days old, or that it has been stored a little too cold. It is not spoiled. Vinegary discard is perfect for savoury crackers, pizza dough, and rye-style breads where the tang is welcome.
How long can I keep sourdough discard?
Up to two weeks in a sealed (but not airtight) jar in the fridge at 4°C. Beyond that, start a fresh jar. Frozen discard keeps for up to three months — defrost overnight in the fridge before use.
Do I have to discard every time I feed?
For a standard 50 g starter on a 1:1:1 feed, yes — otherwise the jar doubles every day. For a smaller starter (10–20 g) on a slower 1:3:3 feed, you can sometimes feed without discarding because the maths works out. Most UK home bakers discard daily and save the discard for the week's bakes.
Is the discard from a young (under-14-day) starter usable?
Not yet. Discard from a young starter is unbalanced — the lactobacilli haven't reached the right ratio, the wild yeast is still establishing. Once your starter is mature (doubling reliably, smells yoghurty at peak), the discard becomes useful. Before that, compost it.
Can I freeze sourdough discard?
Yes — spread it thin in a freezer bag, freeze flat at -18°C, and it keeps for up to 3 months. Defrost overnight in the fridge before use. Frozen discard loses most of its yeast activity but keeps its flavour, so it suits pancakes, crackers and brownies, not bread that needs to rise on the discard alone.
What's next
If discard is your way in, start small. Pancakes Saturday, crackers Sunday, the jar refilled by Wednesday. For the full picture of what to bake, here's our 25 sourdough discard recipes. Welcome to the jar.
If you haven't got a starter yet and want to skip the 10-day wait, our kits ship live, ready-to-bake culture.
