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Potato Yeast (Boil one cup hops in a sack)
Boil one cup hops in a sack in two quarts water for fifteen minutes; remove sack with hops, add immediately after grating (to prevent their darkening) five good-sized Irish potatoes, peeled and grated raw, one cup white sugar, one table-spoon salt, and one of ginger; stir occasionally and cook from five to ten minutes, and it will boil up thick like starch; turn into a jar, and when just tepid in summer, or quite warm in winter, add one-half pint good yeast (always save some to start with); set jar in a large tin pan, and as often as it rises stir down until fermentation ceases, when it will be quite thin. Cover closely, and set away in a cool place, and it will keep two weeks. When yeast smells sour but does not taste sour it is still good; if it has no smell it is dead. One cup will make six good-sized loaves. - Mrs. D. Buxton.
This is a bread starter, not a bake: a hopped potato batter that carries live yeast from one baking to the next. It works, but it depends on having active yeast to begin with and on keeping the jar cold.
- "One cup hops in a sack"Dried hop cones, tied in a scrap of muslin or cheesecloth so they can be lifted out whole. A cup of whole cones is loose and light — roughly 1/2 to 1 oz. Whole-leaf hops from a homebrew supplier are the right thing; pellets will cloud the liquid and are hard to strain.
- Grate the potatoes lastThe instruction to add them "immediately after grating" is the hinge. Raw grated potato oxidises to grey-brown within minutes, so grate directly into the hot hop water. Five good-sized potatoes means somewhere around 2 lb peeled.
- "Irish potatoes"Nineteenth-century American usage for the ordinary white potato, distinguishing it from the sweet potato. Any starchy variety works; a floury russet thickens best.
- The starch gelatinises, it does not boilFive to ten minutes of stirring over heat sets the mixture "thick like starch." That gelatinised starch is the food supply for the yeast. If it scorches on the bottom the whole batch takes on a burnt taste that carries into the bread.
- Temperature before adding the yeast"Just tepid" means lukewarm, around 100F, and safest no warmer than about 110F; yeast begins to suffer above roughly 120F and is killed nearer 140F. The seasonal distinction seems to be about the room rather than the jar: in a cold winter kitchen a warmer batter holds its temperature long enough to start fermenting.
- "One-half pint good yeast"A cup of a previous batch of this same liquid yeast. Starting from scratch, a packet of commercial yeast bloomed in a little of the cooled batter will establish it, after which you keep back a cup each time as the recipe instructs.
- The tin pan is not optionalA vigorous potato yeast climbs the jar and goes over the rim. Stand the jar in a wide pan and stir the foam down each time it rises, until the liquid settles thin and quiet — usually a day or two at room temperature.
- Storage and the smell testTwo weeks in a cool place assumes a cellar or springhouse at 50-55F; a refrigerator is better and longer. The advice about sour smell but not sour taste is sound — the smell is alcohol and lactic acid from ordinary fermentation, while a flat, odourless jar has nothing living in it.
- Ginger's purposeA tablespoon of ground ginger in two quarts was generally credited with encouraging fermentation rather than added for flavour; at one cup of yeast to six loaves, little of it would carry through to the bread.
- YieldAbout two quarts of liquid yeast; at one cup to six good-sized loaves, a single batch covers a great many bakings, with a cup held back each time as seed.
Before packaged yeast was reliable and cheap, a household's leaven was a standing possession, kept alive from week to week and lent to neighbours when a batch died. Hops appear in nearly every American recipe of this kind: the resins in the cones are mildly antibacterial and were generally credited with keeping the jar from turning sour or ropy while the yeast itself worked. Buckeye Cookery (1877, out of Marysville, Ohio) devotes a whole section to yeasts precisely because the choice mattered — potato yeast, hop yeast, salt-rising, milk yeast and dry yeast cakes each gave a different flavour and a different degree of dependability, and a cook's bread reputation rested on which she kept. Compressed fresh yeast was already being sold in American cities by the 1870s and 1880s, and within a generation recipes like this one had moved from the front of the book to the back, then out of it entirely.