Wheat flour
Milled wheat endosperm, and the only common flour whose proteins form gluten in the way baking depends on.
Also called plain flour (UK); all-purpose flour (US) — Broadly equivalent in use, though typical protein content differs between markets, so results are not identical.
Wheat flour is the default structural ingredient in baking because of one property no other common grain shares in the same degree: its glutenin and gliadin proteins, when hydrated and worked, form gluten — a network that is both elastic and extensible, and therefore capable of trapping gas and stretching as that gas expands.
Rye contains related proteins but does not form a comparable network. Most other flours contain none at all. This is why gluten-free baking is not a substitution problem but a reconstruction problem: the structural role has to be rebuilt from starches, gums and proteins that behave differently.
The two numbers that matter most about a given flour are its protein content, which sets the ceiling on the network it can build, and its extraction rate, which determines how much bran and germ came along with the endosperm.
Composition and specification
Protein content
Plain and all-purpose flours generally sit in the lower part of the bread-flour range and below it, while flours sold for bread sit higher. Exact figures are set by the miller and printed on the bag, and vary by market, harvest and grade.
Deliberately stated without a number. Protein figures quoted as properties of a flour TYPE are misleading: they describe particular products in particular markets, and the bag is a better source than any reference site.
RecordedU.S. Department of Agriculture, Agricultural Research Service, Jan A. Delcour and R. Carl Hoseney, AACC International
UK compositional requirements
Flour sold in the United Kingdom is subject to statutory compositional requirements: calcium carbonate, iron and niacin must be added to wheat flour other than wholemeal, and folic acid joins them under a 2024 amendment that England's millers must meet by 13 December 2026. Wholemeal flour and flour from a small mill are exempt.
The 1998 instrument is the frame and the 2024 amendment is what changed; both are cited. The other UK nations legislate separately and this describes England. No quantities are given here — they are set in the instrument, they moved in 2024, and a summary that carried figures would go stale the next time they move.
RecordedUnited Kingdom, Statutory Instrument 1998 No. 141, United Kingdom, Statutory Instrument 2024 No. 1162
What changes if it is left out
There is no general substitution. Removing wheat flour removes the structural network, and every gluten-free approach rebuilds that role from a combination of starches, alternative proteins and hydrocolloids rather than replacing it with one ingredient.
Unsourced because it is a statement about the absence of an equivalent rather than a claim about a measured property. What replacing the network actually involves is set out in the gluten-free flour blends guide rather than summarised here.
RecordedTrue by definition rather than by measurement
Storage and deterioration
White flour keeps well in cool, dry, sealed storage. Wholemeal flour carries the bran and germ, and with them the grain’s own lipase — so its shorter life is enzymatic before it is oxidative: lipase hydrolyses the oil into free fatty acids, and those are what then oxidise. Cold storage slows the enzyme, which is why refrigerating wholemeal flour helps and refrigerating white flour achieves little.
No shelf life is stated deliberately. The source read establishes the mechanism and reports that lipase activity varies up to 2.5-fold between wheat cultivars, which is precisely why a single number for how long wholemeal flour keeps would be wrong — and the commonly quoted eight-weeks figure is cited by that paper from earlier work rather than measured in it.
RecordedPLOS One 18(3), e0282510 — Wei, Yates, Zhu, Hund, Studer and Nystrom, Jan A. Delcour and R. Carl Hoseney, AACC International
Why 'strong’ and 'weak’ are more useful than a protein number
Bakers describe flour as strong or weak, meaning the dough it makes is more or less resistant to deformation. That is not quite the same as high or low protein, because protein QUALITY matters alongside quantity — two flours with the same protein figure can behave differently.
This is one reason a recipe that works with one bag can behave oddly with another at the same stated protein content, and why substituting flours is best judged by how the dough handles rather than by matching a number.
Related
What it does
Structure building
Wheat is the only common flour whose proteins form a network both elastic and extensible enough to trap and hold gas.
Fermentation substrate
Flour’s own enzymes break starch into fermentable sugars, which is why a lean dough with no added sugar ferments perfectly well.
Gas retention
THE ANCHOR OF THE WHOLE MODEL. Wheat flour performs gas retention through the gluten network it forms, which is why the function is not a gluten-free invention — it was always being performed, by an ingredient nobody had to think about.
Structure building
THE SECOND MECHANISM, and the reason wheat flour needs two edges rather than one. Flour builds structure through its gluten network AND through starch that gelatinises and sets — which is why a cake, where gluten is deliberately restrained, still has a crumb that holds. Modelling only the gluten route would make wheat flour look unable to do what it plainly does in a batter.
Can be replaced by
Bread flour— for structure, and it changes the amount of it
SCOPED IN SPRINT 4. Authored in Sprint 1 before the scope field existed, and it was making exactly the flat claim the substitution model was later built to prevent. Both flours build structure; they build different amounts of it. Works in either direction for most bread. Substituting bread flour into a cake or pastry produces toughness, and substituting plain flour into bread gives a slightly tighter crumb and less tolerance of long fermentation.
Gluten-free flour blend— in cakes and biscuits, where gluten was being suppressed anyway
The closest gluten-free substitution gets to straightforward. In a cake or a shortbread most of the structure already came from egg, fat and gelatinised starch, and gluten was being actively restrained — so removing it costs comparatively little. Expect a more tender, more fragile crumb that stales faster, and cool it completely before cutting.
Xanthan gum— for gas retention only, and for none of gluten’s other three jobs
The substitution everyone means when they say xanthan replaces gluten, stated at its true scope. It supplies viscosity and therefore gas retention. It contributes no extensibility of the kind a gluten network has, no protein structure, nothing to browning and nothing to flavour. More of it reduces loaf volume rather than increasing it.
Psyllium husk— for gas retention and handling, at a measured cost in crumb gumminess
Goes further than the gums on handling: the gel is cohesive enough that a gluten-free mixture can be shaped rather than poured. The measured trade is a harder, gummier crumb with fewer and larger cells, which is the same property read as a benefit and as a cost.
Almond flour— only where fat and tenderness were wanted, and never in bread
Almond flour contains no starch, so the setting mechanism every other flour here relies on is simply absent. It works where egg supplies the structure and richness is wanted — macarons, financiers, dense cakes — and cannot make bread at all. It is also not interchangeable with a starch blend by weight, because the fat changes the formulation.
Spelt flour— for structure, with less mixing and a shorter window
It forms a gluten network, so the structural function survives. What changes is the timing: bakers report consistently that a spelt dough reaches its best condition sooner and passes it sooner, which makes it a substitution that needs watching rather than recalculating. It is NOT gluten-free and is not safe in coeliac disease.
Semolina— only where the coarser particle and slower hydration are wanted
Not a like-for-like swap. Coarse particles hydrate more slowly and less completely, so a dough can be stiff at mixing and slack twenty minutes later — and the colour and chew change with it. Finely milled durum is much closer, and the two are sold under overlapping names.
The science behind it
Everything wheat flour does structurally follows from how glutenin and gliadin behave on hydration and working.
The default the strength question is asked about.
Compared in
The general-purpose flour, which makes perfectly good bread and is the right choice for most other things.
Plain flour vs self-raising flour
One side of the comparison.
One side of the comparison.
Wholemeal flour vs white flour
One side of the comparison.
One side of the comparison.
Why rye has the proteins and cannot build the network, and why that makes it a different material rather than a weaker flour.
Not a flour with the gluten taken out: a nut with no starch in it, which is a much larger substitution than the name suggests.
How far a partial substitution goes before the missing network starts to show.
An isolated starch against a whole grain, and the naming trap where each country's word means the other's other product.
Commonly confused with
Indistinguishable in the bag and different in the dough, with the naming differing between markets on top.
The naming makes this worse than it needs to be: British cornflour is American cornstarch, and American corn flour is a different product again.
Cultures built from this
Flour supplies the starch the culture’s enzymes convert to sugar, and the minerals the organisms need. Changing the flour changes how fast the culture works — but not, on the evidence, which organisms live in it.
A levain is built from the starter plus fresh flour and water, at whatever hydration the loaf needs rather than whatever the maintained culture is kept at.
Covered in
Why grams and cups do not convert cleanly
Flour is the ingredient the question is almost always asked about, and the one where the packing spread is widest.
The flours, and what actually separates them
The default the others are described against.
Used in
Plain or wholemeal; no strength is needed because no network is built.
Ordinary bread flour is usual; strength matters less at this size.
Plain flour; no strength wanted.
Plain flour, in equal weight to the rest in the classical form.
Plain flour.
A small quantity, folded in without knocking the air out.
Plain flour; strength is not wanted.
Plain flour.
Plain flour.
Plain flour, worked just enough to hold.
History and culture
How flour became white, and what that cost
What roller milling made cheap.
Keep reading
Bread flour
Indistinguishable in the bag and different in the dough, with the naming differing between markets on top.
Gluten development
The mechanism underneath, separated from what is settled and what is not.
Every ingredient, by what it does
Grouped by function rather than by shelf, so a substitution question has somewhere to start.