When baking stopped needing time

Before chemical leavening, raising a dough meant fermentation, and fermentation meant time, warmth and a living population to look after. Every domestic baking tradition was shaped by that constraint: bread was baked infrequently, in quantity, and made to keep.

An alkali reacting with an acid produces carbon dioxide immediately and needs nothing to be alive. That removed time, warmth and maintenance from the requirements in a single step, and the products that followed — soda bread, cornbread as it is now made, scones, quick breads, most cakes as they are now made — are the ones that step made possible.

It also changed the shape of the domestic day. A bread that can be mixed and baked inside an hour is a different household object from one that has to be planned around.

Bicarbonate of soda needs an acid to react with. In nineteenth-century kitchens the acid available was usually soured milk or buttermilk, which is a by-product of butter-making and was therefore to hand. That is the practical reason so many traditional soda-leavened recipes call for buttermilk rather than a nutritional or flavour one.

Baking powder is the later refinement: bicarbonate with a dry acid already blended in, plus a starch to keep the two apart in the tin. It made the reaction independent of what else was in the recipe, which is why it displaced bare bicarbonate for most purposes.

The consequence for a modern baker is direct. A recipe with bicarbonate and no acid will not rise properly and will taste of the residue; a recipe with baking powder does not need buttermilk for leavening, though it may want it for flavour and tenderness.

The commercialisation of chemical leaveners involved several competing formulations, several countries and a good deal of subsequent marketing, and the popular accounts name individuals with a confidence the record does not support.

This site states the mechanism and the period, and does not attribute the invention to a person. Where a reader meets a confident attribution, it is worth knowing that the chemistry was described before anybody packaged it and that the packaging was contested.