Self-Raising Flour

Self-raising flour — self-rising flour in American usage — is ordinary soft white wheat flour with a chemical leavening system already blended in: baking powder (a mix of an alkali, sodium bicarbonate, and one or more acid salts), usually with a little salt. It is a convenience product, engineered so a baker can make cakes, scones, muffins, quick breads and dumplings rise without measuring out and folding in a raising agent. Wet the flour and heat it, and the acid and the bicarbonate react to release carbon dioxide, which puffs the batter or dough into a light, tender, even crumb — no yeast and no waiting for fermentation. Because its lift comes from chemistry rather than kneaded gluten, self-raising flour is typically milled from softer, lower-protein wheat than bread flour, giving the delicate, cakey texture its bakes are prized for. On its own it is bland and faintly sweet like any white flour, smelling only of dry cereal, sometimes with the merest saline or metallic edge from the added baking powder.