Reference · Beginner

Sourdough FAQ & Glossary: Common Questions and Terms Explained

Plain-English answers to the most common sourdough questions, plus a glossary of the terms — starter, levain, hydration, bulk fermentation, autolyse — every baker needs.

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Sourdough loaf, active starter and separate levain on a baking bench

Updated Oct 2026 · 8 min read

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Sourdough has its own vocabulary, and that vocabulary trips up almost every new baker. Recipes casually mention “levain,” “autolyse,” “bulk,” and “75% hydration” as if everyone already knows what they mean. This page is the plain-English reference: the concepts people ask about most, followed by a glossary of the terms you’ll meet again and again.

The big picture: what sourdough actually is

Sourdough is bread raised by a living culture instead of a packet of yeast. That culture — the starter — is a community of wild yeast and lactic-acid bacteria living in a simple mix of flour and water. The yeast produces gas that makes the dough rise; the bacteria produce acids that give sourdough its tang and help preserve the loaf.

Everything else flows from that one idea. Because the culture works slowly, fermentation takes hours rather than minutes. Because it’s alive, it needs feeding and responds to temperature. And because there’s no standardised commercial yeast doing the work, you learn to read the dough rather than follow a stopwatch.

Starter vs levain

This is the single most common point of confusion, so it’s worth being precise.

Starter (mother culture) The culture you keep alive indefinitely — you feed it, store it, and never use all of it. See the active starter guide.
Levain A fresh build made from a small portion of that starter for one specific bake. You grow it to the size the recipe needs, let it ripen, and use the whole thing.

In practice, many home bakers blur the line and just call a peak-ripe starter their levain. To size a build precisely, the levain calculator does the math. The feeding ratio chart explains how much fresh flour and water to feed it.

Why is my bread dense, gummy, or flat?

These are the classic beginner problems, and they almost always trace back to fermentation. Match the symptom to the likely cause:

Dense and flat usually under-fermentation or a weak starter — the dense sourdough guide walks through it.
Gummy crumb often sliced before cooling or slightly underbaked — check the internal temperature guide.
Spreads, won't hold shape likely over-proofed or too high in hydration for your flour.

Hydration and discard basics

Two more terms that come up constantly.

Hydration Water weight as a percentage of flour weight. More water = a wetter, more open crumb but stickier dough. Beginners do best around 65–70%. The hydration calculator keeps flour and water balanced.
Discard The portion removed before feeding so the culture stays strong. Not waste — it makes excellent pancakes, crackers, and waffles. Fridge storage with weekly feeding cuts down how much you discard.

Is sourdough actually healthier?

The long, slow fermentation predigests some of the starch and gluten and tends to lower the bread’s glycaemic impact compared with fast commercial loaves, and the acids can improve mineral availability. It’s still bread and still carbohydrate-rich, but many people find genuine long-fermented sourdough gentler on digestion than standard supermarket bread.

Sourdough glossary

Keep this list nearby while you bake — these terms show up in nearly every recipe.

Starter (mother culture) the living mix of flour, water, wild yeast, and bacteria that leavens your bread; maintained indefinitely.
Levain a fresh build of culture made from a portion of your starter for a single bake.
Feeding (refreshing) adding fresh flour and water to renew the starter's food supply; the proportions are the feeding ratio.
Discard the portion removed before feeding so the culture doesn't grow endlessly; usable in many recipes.
Hydration water weight as a percentage of flour weight; sets how wet and open the dough and crumb are.
Autolyse a rest after mixing just flour and water that hydrates the flour and jump-starts gluten.
Bulk fermentation (first rise) the long fermentation of the whole batch after mixing and before shaping.
Stretch-and-fold gently stretching and folding the dough during bulk to build gluten without kneading.
Shaping / pre-shaping forming the dough into a taut round or oval that holds structure; a light pre-shape precedes the final shape.
Proofing (final proof) the last rise after shaping, before baking — often done cold in the fridge.
Cold proof (cold retard) proofing the shaped loaf in the fridge 8–16 hours to deepen flavour and ease scoring.
Banneton a cane or wood-pulp basket that supports the shaped loaf and leaves the spiral pattern.
Oven spring the rapid final rise in the first minutes of baking, before the crust sets.
Scoring slashing the top of the loaf just before baking so it expands in a controlled way.
Crumb the interior texture of the loaf; "open crumb" means large, irregular holes.
Over-proofing letting the dough ferment too long so it loses strength and rise.
Float test dropping a spoonful of starter in water; if it floats, it's gassy and likely ready to bake with.

Where to go next

If a term here sparked a question, the linked guides go deeper. Start with the active starter guide if your culture isn’t behaving, the bulk fermentation guide to learn to read the dough, and the no-knead recipe for a forgiving first bake.

Find the right troubleshooting path

ProblemStart by checkingDetailed next step
Starter is slowFeed ratio, temperature and recent storageStarter readiness
Liquid on starterWhole-jar appearance and feeding historyHooch
Fuzzy growth or pink/orange colourContamination signsMold and discard decisions
Dough tears during foldsRest, hydration and flour strengthFold comparison
Dough spreads late in bulkWhether it retains cohesionOverproofing
Gummy baked centreBake completion, cooling and formulaInternal temperature
Uncertain crumbWhole bake record, not one holeCrumb decisions

Do not apply all fixes together. Preserve the flour and basic formula for the next attempt, record actual dough temperature and change the factor most supported by your observations.

FAQ

Frequently asked questions

What is sourdough, exactly?
Sourdough is bread leavened by a natural culture of wild yeast and lactic-acid bacteria instead of commercial baker's yeast. That culture, called a starter, ferments the dough over hours, producing the rise, the tangy flavour, and the open crumb that define sourdough. No packaged yeast is used.
What is the difference between a starter and a levain?
A starter is the culture you keep alive and feed long-term — your mother culture. A levain is a separate, often larger build made from a spoonful of that starter specifically for one bake. Think of the starter as the source you maintain forever and the levain as the portion you grow fresh for a particular loaf, then use up entirely.
What does hydration mean in sourdough?
Hydration is the weight of water in a dough expressed as a percentage of the flour weight. A dough with 750g flour and 500g water is about 67% hydration. Higher hydration gives a wetter, stickier dough and a more open crumb; lower hydration is firmer and easier to handle. Most beginner recipes sit around 65–75%.
Why is my sourdough so dense and flat?
The most common cause is under-fermentation paired with a weak starter. Make sure the starter doubles reliably within 4–8 hours of feeding before you bake with it, give bulk fermentation enough time for the dough to look puffy and risen, and build strength with stretch-and-folds. Over-proofing can also cause a flat loaf, so judge the dough by feel rather than the clock.
Do I have to discard part of my starter every time I feed it?
When you are maintaining a starter at room temperature, yes — discarding keeps the culture from growing endlessly and keeps the ratio of fresh flour to old culture high enough to stay strong. You do not have to throw it away, though; discard can go into pancakes, crackers, and waffles. If you store the starter in the fridge and feed weekly, you discard far less often.
How long does it take to make a sourdough starter from scratch?
About 7 to 14 days. You mix flour and water and feed it daily; wild yeast and bacteria colonise it over the first week, and it becomes strong enough to leaven bread once it doubles predictably within hours of each feed. Warmer kitchens and whole-grain flours speed early activity, but reliable rising strength is what tells you it is ready, not the calendar.
What is bulk fermentation and how do I know when it is done?
Bulk fermentation is the first long rise, after mixing and before shaping, when the whole batch of dough ferments together. It is done when the dough has risen by roughly 30–75% (depending on your recipe and temperature), looks puffy and domed, shows bubbles on the surface and sides, and jiggles when you shake the bowl. Temperature drives the timing far more than the clock does.
Is sourdough healthier than regular bread?
Sourdough's long fermentation breaks down some of the starches and gluten and lowers the bread's glycaemic impact compared with fast-risen commercial bread, and the acids can make minerals more available. It is still bread, so it is not a low-carb food, but many people find naturally fermented sourdough easier to digest than standard loaves.
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