Gluten-Free Sourdough Troubleshooting: Gummy Crumb, Flat Loaves, and More
Gluten-free sourdough is one of the most rewarding things you can bake — but it's also one of the most unforgiving. Unlike wheat-based dough, there's no gluten network to hold everything together, so small mistakes in fermentation, hydration, or flour ratios can cause big problems in the final loaf.
The good news? Almost every common gluten-free sourdough problem has a clear cause and a straightforward fix. This guide walks through each one, so you can diagnose what went wrong and know exactly what to change next time.
For a full overview of the process from starter to finished loaf, start with our Complete Guide to Gluten-Free Sourdough Bread.
Why Is My Gluten-Free Sourdough Gummy Inside?
A gummy or wet crumb is the most common complaint with gluten-free sourdough. You slice into what looks like a decent loaf, and the inside is dense, sticky, and almost raw-looking. Here's what causes it.
The dough was under-baked
Gluten-free loaves hold onto moisture far longer than wheat loaves. Even if the outside looks golden and done, the inside can still be wet. Most gluten-free sourdough loaves need to bake at around 200–210°C (390–410°F) for 55–70 minutes. If yours is consistently gummy, add 10–15 minutes to your bake time and check the internal temperature — it should reach at least 96°C (205°F).
Use a probe thermometer rather than guessing. Thermapen make reliable options used by professional bakers.
The loaf wasn't cooled properly
This is one of the most overlooked steps. When a gluten-free loaf comes out of the oven, the starches inside are still setting. Cutting into it too soon — even after 20 minutes — can cause the crumb to compress and turn gummy. Wait at least 1.5 to 2 hours before slicing. Cooling on a wire rack (not left in the tin) helps moisture escape from the bottom too.
The hydration was too high
Gluten-free flour blends absorb water differently depending on which flours they contain. Rice flour absorbs quickly; psyllium husk absorbs slowly and expands over time. If your dough looked fine going into the tin but baked up gummy, try reducing your water by 10–20g on the next bake and see if that changes the crumb.
There wasn't enough binder
Psyllium husk is the most critical ingredient in gluten-free sourdough — it acts as the structural substitute for gluten, trapping gas and holding the crumb together. If you're getting a gummy result, check that you're using whole psyllium husk (not psyllium powder, which is more concentrated) and that your recipe uses enough. A typical ratio is around 10–15g of whole psyllium husk per 400g of flour blend.
Why Is My Gluten-Free Sourdough Flat?
A flat loaf usually means the dough didn't hold enough gas during fermentation or baking — either the starter wasn't active enough, the dough over-fermented, or the structure couldn't support the rise.
The starter wasn't active enough
A gluten-free sourdough starter needs to be genuinely active and bubbly before you use it. A sluggish starter will produce very little lift. Feed your starter 4–8 hours before mixing — it should double in size and look actively bubbling when you use it. If it's consistently slow, it may need a few extra feeds to build strength. Our guide on how to make a gluten-free sourdough starter covers feeding schedules in detail.
The dough over-fermented
Over-fermentation is a common trap with gluten-free sourdough. Unlike wheat dough, there's no strong gluten network to hold gas under pressure — so if the dough goes too far, the starches break down and the structure collapses. Signs of over-fermentation include a very sour smell, bubbles throughout the batter, and a loaf that rises briefly in the oven then sinks. Ferment at room temperature (around 21–24°C) and check for readiness after 4–6 hours rather than leaving it overnight.
The tin was too large
If your loaf looks flat, check whether your tin is the right size. A 1kg gluten-free sourdough loaf needs a tin of roughly 900g or 2lb capacity. In a tin that's too large, the dough spreads sideways instead of rising upward, giving you a wide, flat result.
Psyllium husk wasn't mixed in properly
Psyllium husk needs time to hydrate and form a gel before the rest of the ingredients are added. If it's mixed in too quickly or unevenly, parts of the dough won't have the same structural support. Mix your psyllium with the water first, let it sit for 2–3 minutes until it forms a gel, then add it to the dry ingredients.
Why Does My Gluten-Free Sourdough Have a Dense, Brick-Like Crumb?
A heavy, compact crumb without any open structure usually comes down to one of three things: not enough leavening, too little fermentation time, or a flour blend that's too heavy.
The starter wasn't strong enough
This is the most common cause of a dense crumb. Use your starter at peak activity — when it's domed on top, full of bubbles, and has roughly doubled from its last feed. A starter that's past peak will still give you some rise, but the crumb will be noticeably tighter. For advice on reading your starter's readiness, see our article on how to know when your sourdough starter is ready to bake with.
Fermentation was too short
Gluten-free sourdough ferments differently from wheat-based dough. You're looking for visible bubbles throughout the batter, a slight dome on top, and a batter that's clearly increased in volume. If fermentation was cut short — perhaps because the kitchen was cold — the dough won't have produced enough gas to give you a light crumb. A proving drawer or a warm spot in the kitchen (near the oven or boiler) can help in cooler conditions.
The flour blend was too heavy
Dense flours like buckwheat, teff, or brown rice flour add flavour and nutrition, but they also add weight. If your blend is too heavily weighted toward these flours, the loaf will struggle to rise and the crumb will be tight. Try increasing the proportion of a lighter flour — white rice flour or tapioca starch — to improve the lift. A blend that's roughly 70% primary flour and 30% starch is a good starting point. See our guide to the best gluten-free flour blends for sourdough for blend ratios.
Why Does My Gluten-Free Sourdough Have a Pale, Thick Crust?
A thick, chewy crust that's pale rather than golden usually means the oven wasn't hot enough, or the loaf didn't get enough direct heat at the base.
The oven temperature was too low
Gluten-free sourdough benefits from a hot start. Preheat your oven for at least 45 minutes before baking, with your Dutch oven or loaf tin inside if you're using one. Starting with a cold or under-heated oven means the loaf never gets the initial burst of heat that creates a good crust and oven spring.
The base isn't getting enough heat
If the bottom crust is pale and the top is browning unevenly, try placing your loaf on the lowest oven rack for the first 30 minutes of baking. A baking stone or baking steel underneath the tin will also help transfer heat directly to the base.
No steam in the first half of the bake
Steam keeps the outer surface of the loaf flexible during the initial rise, which allows the crust to expand properly. Without it, the crust sets too quickly and comes out thick and pale. Baking in a covered Dutch oven for the first 20–25 minutes provides natural steam. If you're using a loaf tin, cover it tightly with foil for the first half of the bake, then remove it to allow browning.
Why Does My Gluten-Free Sourdough Crack on the Sides?
Side cracking — where the loaf splits along the sides rather than rising from a scored top — usually means the surface set too fast before the interior had finished expanding.
The dough was too cold going into the oven
If the dough went straight from the fridge into a hot oven, the outside can set before the inside has warmed up enough to rise. Allow your shaped loaf to sit at room temperature for 30–45 minutes before baking if it's been in the fridge overnight.
The loaf wasn't scored
Scoring — making deliberate cuts in the surface — gives the loaf a controlled place to expand. Without it, the pressure of oven spring pushes through wherever the surface is weakest, often along the sides. A sharp knife or bread lame scored along the top before baking will direct the rise upward.
Why Does My Gluten-Free Sourdough Taste Sour or Acidic?
Some tang is expected in sourdough — it's part of the character. But an unpleasant sharpness usually means fermentation went too far or the starter is too acidic.
The dough over-fermented
The longer gluten-free sourdough ferments, the more acidic it becomes. If your loaf tastes sharply sour, reduce the bulk fermentation time by an hour on the next bake, or move the dough to the fridge sooner to slow things down. Cold fermentation in the fridge (at around 4°C) produces a milder, more balanced flavour than a long room-temperature ferment.
The starter needs refreshing
An old starter that hasn't been fed regularly will be very acidic. Before baking, give your starter at least one or two feeds on consecutive days to refresh it. A well-maintained starter should smell pleasantly tangy — not vinegary or sharp. For full starter care advice, see our guide on maintaining a sourdough starter.
Quick-Reference Troubleshooting Table
| Problem | Most Likely Cause | First Fix to Try |
|---|---|---|
| Gummy crumb | Under-baked or cooled too soon | Bake longer, cool for 2 hours before slicing |
| Flat loaf | Weak or over-peaked starter | Use starter at peak activity |
| Dense crumb | Too little fermentation or heavy flour blend | Extend ferment time; lighten flour blend |
| Pale, thick crust | Oven too cool, no steam | Preheat longer; use covered Dutch oven |
| Side cracking | Dough too cold; not scored | Score the top; let dough warm up before baking |
| Too sour | Over-fermented or acidic starter | Shorten ferment; refresh starter before baking |
Want to Bake Gluten-Free Sourdough With an Expert?
Troubleshooting from a recipe is useful, but having a teacher watch your technique and give real-time feedback is far faster. In our Gluten-Free Sourdough Workshop, you'll mix, shape, and bake your own loaf in a small group setting — and leave with a live starter, a recipe pack, and the confidence to keep going at home.
Not sure which workshop suits you? Read our comparison guide to the Classic, Rye, and Gluten-Free workshops to find out which one is the right fit.
Related reading: Is Sourdough Bread Easier to Digest? — the science behind fermentation and digestibility, including what it means for gluten-sensitive bakers.
