Dry Yeast
Boil two large potatoes and a handful of hops (the latter in a bag) in three pints water; when done, take out potatoes, mash well, add one pint flour, and pour boiling hot water over all; beat well together, adding one table-spoon salt, one of ginger, and one-half cup sugar; when luke-warm add one cup good yeast and let stand two days (or only one day, if very warm weather), stirring down frequently; add good white corn meal until thick enough to make into cakes about half an inch in thickness; place to dry in the shade (never expose to the sun or to stove heat) where the air will pass freely, so as to dry them as soon as possible, as the fermentation goes on as long as there is any moisture; turn the cakes frequently, breaking them up somewhat, or even crumbling, SO they will dry out evenly and quickly; when thoroughly dried put in a paper sack, and keep in a dry place. A small cake will make a sponge sufficient to bake five or six ordinary loaves. - Mrs. E. T. Carson
This is a starter-propagation recipe: a wild-and-cultivated yeast culture carried in dried cakes, which was how a household kept leaven alive before packaged yeast. It works, but it depends entirely on getting the cakes bone dry.
- The hinge is drying speedFermentation continues as long as moisture remains, and a slow-drying cake sours or moulds instead of going dormant. Thin cakes, frequent turning, crumbling, and steady moving air matter more than anything else in the method; no sun and no stove heat, because sustained heat weakens the culture and temperatures approaching 130-140F kill yeast outright.
- QuantitiesThree pints is 6 cups. Two large potatoes means roughly 1 lb; a handful of hops is about 1/2 oz of dried hop flowers, tied in cheesecloth so they can be lifted out. The final cornmeal quantity is deliberately open — you add until the mass will hold a shape.
- "One cup good yeast"This means a cup of active liquid yeast or a previous batch's sponge, not dry granules. Without an existing culture the recipe has no reliable start; a mature sourdough starter is the nearest modern equivalent, though the resulting culture will not be the same one Mrs. Carson had.
- White corn mealPlain stone-ground white cornmeal, not a self-rising mix and not masa. Its job is to absorb moisture and give the cake a crumbly body that dries through rather than glazing over.
- Ginger and sugarGround ginger turns up in a good many nineteenth-century yeast recipes, where it was thought to keep the ferment lively and check souring; the half cup of sugar is food for the yeast, not sweetening. The tablespoon of salt would also tend to slow the ferment, though the recipe does not say why it is there.
- Timing and temperatureTwo days at ordinary room temperature, one in summer heat, stirring down whenever it domes. Judge by smell: pleasantly beery and yeasty is right, sharply vinegary or acetone-like means it has gone too far.
- Storage and strengthA paper sack in a dry cupboard is correct — an airtight jar traps any residual moisture. Even well dried, the cakes lose vigour over weeks, so expect longer rises than the original claim of five or six loaves from a small cake.
- SanitationAn open culture picks up whatever is in the room. Use scalded bowls and utensils, and discard any batch that grows fuzzy or coloured mould while drying rather than trimming it.
Before compressed cake yeast became widely available in American groceries in the last quarter of the nineteenth century, a baking household generally had to keep its own leaven — though some bought it from bakers and brewers — and printed cookbooks devoted whole sections to the problem. Hops were near-universal in these recipes: their resins are mildly antibacterial and help suppress the souring organisms that compete with yeast, which is the same property that made them useful in beer. Potato and flour supply starch and sugar, and drying the culture into cornmeal cakes was the standard way to make it portable and storable, so a good yeast could be shared between neighbours and revived weeks later.