Choosing Flour: Protein Is the Whole Story

The difference is one number

What is on the bag is not a use but a protein percentage.

• Bread flour: 12-14%, from a different wheat (hard wheat).
• Plain / all-purpose: 10-11%.
• Cake flour: 7-9%, from soft wheat.

The proteins — glutenin and gliadin — meet water and, once worked, form a gluten network (dough and gluten). More protein gives a tighter, chewier net; less gives a looser, tenderer one.

Within wheat that is the whole mechanism. Outside wheat the sentence fails in two different ways.

• The protein is there and no network forms. Rye has glutenin and gliadin too. But rye is full of pentosans, gums that hold up to eight times their weight in water and sit physically between the proteins, so no amount of working builds a net. The structure of Pumpernickel is a gum, not a protein — which also means kneading time is meaningless there.
• There is more protein than in wheat and still none forms. Chickpea flour has more protein than wheat and makes no gluten at all, because pulse protein is globular storage protein that cannot link up. In Farinata that shows up as a convenience: beat it as hard as you like. The exact reverse of "mix as little as possible".

Corn is a third case, with no net to build in the first place — and what fills that gap separates the dishes. Sopa Paraguaya fills it with cheese and egg; Cornbread fills it with soda, buttermilk and a preheated pan.

The premise that flour is raw

All three cases above ask whether a network forms. Underneath that question sits a second premise, never stated: flour is raw, and heat arrives later to cook it. That is what lets this page be about protein and nothing else.

Estonia's kama breaks it. Barley, rye, oats and peas are roasted as whole grain before they are milled, so by the time there is flour the starch has already been broken down into dextrins and some of it has set gelatinised. Stirred into cold kefir it tastes cooked, and no oven appears anywhere in the recipe. The interesting number here is not the protein but what state the starch is in — and the peas are in the mix to add protein, not to build anything with it.

Cooking flour is not itself new. Mohinga dry-toasts chickpea flour, and a roux (thickening sauces) cooks flour in butter to lose the raw taste at the cost of thickening power. The difference is what comes next: both of those still boil the flour afterwards. With kama the roasting is the cooking, which is what makes a confection like dasik — where heat never appears at all — possible.

And the premise that it arrived milled

The section above asks whether the starch has already been cooked. There is a second thing the bag settles before it is opened: the grain was dried, and then ground. A percentage can be printed on a sack precisely because the milling happened long before any cooking, to something with almost no water in it. Grind the grain wet and none of that survives — no bag, no number, and the choices left over are different ones.

• They are not the same ingredient, and the pages that substitute record the price. Songpyeon asks for wet-milled rice flour, "the salted damp kind from a rice mill or the freezer aisle", and writes down what the dry supermarket sort costs: "about 20% more water and knead longer, and expect cracking anyway." Sel roti files rice flour under "no time to soak and grind" — a shortcut rather than the standard. Cheung fun keeps the stone-ground version as a dish with its own name, lai cheung fun, "soaked rice ground on a stone mill into batter on the spot".
• The fineness stops being a grade and becomes a decision. The nearest thing on this page is that 00 describes how finely flour was milled — printed on the bag, and chosen in a shop. Ground at home it is set at the moment of grinding, and the dishes that do it say the setting is the dish: bindaetteok grinds coarse because "taken smooth, it becomes an ordinary batter and there is nothing left to tell them apart"; dosa leaves "a slight semolina-like grit"; falafel stops at "a coarse, sandy texture — crumbly, not a paste".
• And the grinding is part of the mixing rather than a step before it. Dosa grinds the urad dal "separately, and first", because the air its mucilage traps is where the fermentation starts — "ground together with the rice, the structure never forms". A milled flour cannot carry a property like that: whatever the grinding released went into a sack months ago. Douhua grinds its soaked soybeans with the whole 2.4L of water and wrings the result out, so grinding and extraction are one action.

None of which makes one better than the other. It makes the Storage section below apply to only one of them: a dry flour's problem is the fat in it going rancid over months, and a wet meal has no months. Why the grain is soaked is in (cooking rice) and how long for is in (soaking); what this page adds is that once it is done, the thing in the bowl is no longer the object this guide describes.

The bran is in the bag and not in the number

The sections above leave wheat behind. This one does not: the flour is ordinary wheat, dried and milled and raw exactly as the top of this page assumes, and the percentage still does not settle what the dough will do. That figure is measured on the flour, and it says nothing about whether the bran was taken out of it.

Sangak is the page that joins the two ends — "bran fragments sit between the gluten strands and cut the network" — and it points at Pumpernickel as having "the same problem far worse, in rye." That puts it on the same axis as the rye bullet at the top of this page: in both, something that is not protein gets physically between the proteins, and no protein figure predicts it. Chapati states the consequence as reassurance in its own step text — kneaded eight minutes, the dough "will never get as springy as a white dough, and that is normal, not a fault."

So the lever this page hands you stops part of the way up, and the recipes say where.

• The limit gets stated as a percentage. Bagel allows wholemeal for "up to 30% of the bread flour. Beyond that the gluten is cut through and the chew disappears" — the chew being what the bread is for. Baguette puts its own at 20%, writing the price down beside it: it "deepens the flavour and costs you volume." Chapati carries no such line, because the whole bread is wholemeal and it is a flatbread with nothing to hold up.
• It drinks, so the hydration moves with it. Bagel adds 15g of water for that 30%, baguette "about 5% more" for its 20%, and Irish soda bread 50ml more buttermilk when 200g of the plain flour is swapped, "since the bran holds water and the same quantity would leave it stiff." Chapati refuses a figure at all — "wholemeal flours take up very different amounts" — and puts the water in bit by bit.
• What buys the strength back is time rather than work. Kneading runs into that ceiling, so sangak takes "an overnight starter, a 30-minute autolyse and four folds instead of a long knead." Chapati's half hour is bran hydration before it is gluten relaxation — "bran hydrates slowly" — and a dough that skipped it "will not roll round however long you work at it" (soaking).

"Wholemeal" is not one ingredient either, and the reason sits next door to the 00 note below. There the fineness of the milling is what changes and the flour is white; here what is being sized is the bran, and the size decides how much cutting it does. Chapati writes it down: "atta is wholemeal ground fine, so the bran is small and the dough is less harsh. Western wholemeal is coarser and rolls badly on its own" — half and half with plain flour gets close.

Which goes where

• Bread flour for anything that must rise and be chewy: bread, pretzels, pizza dough. Croissants blend bread and plain, because the dough has to hold layers without turning tough.
• Plain flour for most noodles, dumpling wrappers and pancakes. The chew of kalguksu and the stretch of a mandu wrapper live in this range.
• Cake flour for things that should crumble: cakes, cookies, and batter. Half of why tempura is crisp is low-protein flour, and the other half is ice-cold water — both are conditions that stop gluten forming (deep frying).

Substituting has a predictable direction. Cake made with bread flour comes out tough; bread made with cake flour rises and then collapses.

Faking one from another

• For cake flour: take 15g out of 100g of plain flour and put 15g of cornstarch back. Starch has no protein, so the overall percentage drops.
• For bread flour: about 5% vital wheat gluten stirred into plain flour gets close. Without it, use plain flour and knead longer instead.
• For plain flour: half bread, half cake.

In something like brownies, where flour is a minor ingredient, the choice barely shows. The more the flour is the structure, the more it matters.

"00" is not a protein grade

Italy's 00, 0, 1 and 2 describe how finely the flour is milled, not its strength; protein is stated separately. Some 00 flours are strong pizza flours and others are soft. "00 means tender" is a misreading.

Semolina and durum are a different wheat entirely (hard durum), coarsely ground. They hydrate slowly and bite firmly, which is why dried pasta uses them. Swapped in for flour, you get a different food.

Things sold beside flour that are not flour

• Wheat starch is what remains after flour is washed to remove the gluten — pure starch, no protein, so it cooks clear instead of setting white and opaque. It is the translucent wrapper of har gow, and plain flour cannot do it at any thickness. Though "remove" is only half right: Liangpi does that washing at home as step one and eats both halves — the settled starch water steamed into translucent noodles, and the ball of gluten left in your hand steamed into a sponge called mianjin and piled on top.
• Pure starches (potato, corn, tapioca) are for thickening, not structure (thickening sauces).
• Self-raising flour already contains baking powder, and some bread flours come pre-mixed with yeast. Read the bag.

Storage

White flour keeps well because it has little fat. Wholemeal does not: oil in the bran oxidises and turns rancid within months. Keep wholemeal refrigerated or frozen (freezing and thawing).

White flour still picks up smells, so keep it sealed. Once it tastes bitter or smells stale there is no fixing it.

Pre-roasted grain flours are a different thing again. Dasik presses roasted rice and bean flour together with nothing but honey, and since no heat is applied at any later point the flour has to be cooked already. Made with raw flour the raw taste simply stays — not a storage question but a different ingredient.