LEAVEN is nothing more nor less than flour and water, stirred together and kept in a warm place until fermentation commences. Every time the baker makes bread, a certain quantity should be kept back in an earthen pot for the next sponge.

The use of leaven is supposed to have originated in Egypt. It is very seldom used in this country now, although in some parts of Cumberland it occurs in the manufacture of a particular kind of brown bread. In some European countries where yeast is not easily obtained leaven is used. Sailors use it on long voyages. But, like most things where fermentation is concerned, care and cleanliness must be observed. But let leaven be ever so well manufactured, the bread made from it has always a rank, sour taste, and is not to be compared with yeast-made bread.

The new system of making bread: a concise and practical treatise on bread and how to make it, with a large quantity of other useful and practical matter, including all the latest systems of quick sponging by Robert Wells, London, 1903, pages 16.

Explicit references to the taste in bread are few and far between.  I point out in my book, Bread, a global history, that the adoption of sourdough bread as a high status bread in America, Britain and other countries with an  Anglo-bread tradition, such as Australia, represented one of the more radical changes in bread preference for which we have documentary evidence. Both British and American 19th-century cookbooks are clear that sourness in bread is a bad thing and that yeast is the premium leavening.

This recipe for leaven by the English author Robert Wells from 1903 makes clear that he saw leaven as a leavening of last resort — you live in France where brewers, the traditional source of yeast are few and far between — or you are stranded in a boat on a long sea voyage. Of course, the sourness of a leaven leavened bread is largely determined by how the recipe is managed. Sourness is generally not appreciated in today’s France thus even though their artisan bakery breads are almost uniformly risen with levain they never taste sour.

Also of interest in this quote from Wells is his assumption that leavened bread originated with the Egyptians. There is no factual basis for this assertion, but you still find it a given in most bread histories that leavened bread was invented in Egypt.