Ingredient

Plain flour

The only number that matters on a bag of flour is the protein content, because protein is what becomes gluten, and gluten is what decides whether the thing you bake is chewy or tender.

Protein becomes gluten

Wheat flour contains two proteins that, once wetted and worked, link into an elastic network called gluten. That network traps gas and gives dough its stretch and its chew. More protein means more gluten means more structure.

A strong bread flour at around 12 to 14% protein makes a dough you can stretch thin and that holds a loaf up. A plain flour at around 9 to 11% makes something softer. A cake or pastry flour at 7 to 9% makes something tender that crumbles.

This is why the flour in a recipe is rarely interchangeable, and it is also why how much you work the dough matters as much as which flour you chose. The same flour will give chewy pancakes if you beat the batter and tender ones if you stop as soon as it comes together.

The flours

Plain / all-purpose, 9–11%

The default. Cakes, biscuits, sauces, batters, pastry. Adequate for bread, if not ideal.

Strong / bread flour, 12–14%

Bread, pizza, pasta, anything that needs structure and chew.

Self-raising

Plain flour with baking powder and usually salt already in it. Convenient; it also ages, and old self-raising flour rises poorly. Roughly two teaspoons of baking powder per 150g of plain flour substitutes for it.

00 flour

An Italian grading of how finely the flour is milled, not how much protein it has. 00 exists in both soft and strong versions. Pizza flour is usually 00 and strong; pasta flour is 00 and softer.

Cake or sponge flour, 7–9%

Low protein, often chlorinated. Very tender crumb.

Wholemeal

The whole grain, bran included. The bran cuts gluten strands, so wholemeal bread rises less and is denser. Absorbs more water.

Handling it

• Weigh it. A cup of flour can vary by 20% or more depending on how it was scooped, which is enough to change a recipe entirely. This is the single largest source of baking failure.
• Fluff, spoon and level if you must use cups — never scoop the cup through the bag, which compacts it.
• Sift when a recipe says so, especially for cakes. It is aerating as much as it is removing lumps.
• Add flour to liquid slowly for sauces, or make a paste first. Dumped in at once it clumps, because the outside of each lump gelatinises and seals the inside dry.
• Stop mixing early for muffins, scones and pastry. Every extra turn develops more gluten.
• Rest doughs. Time lets the flour hydrate fully and lets gluten relax, which is why rested pastry shrinks less and rested pasta rolls thinner.

Flour as a thickener

Flour thickens by starch gelatinisation: the granules absorb water, swell and burst, and the released starch thickens the liquid. It needs heat and it needs time — a sauce thickened with flour and not cooked out tastes raw and pasty.

The two standard routes are a roux, where flour is cooked in fat before liquid is added, and beurre manié, where soft butter and flour are kneaded together and whisked into a finished sauce. A roux is more stable and can be cooked to different colours; beurre manié is a last-minute fix. Both need a few minutes of simmering afterwards to lose the raw taste.

Cornflour is the alternative and behaves quite differently — see cornflour.

Common questions