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Potato Yeast (Take as many hops as can be)
Take as many hops as can be grasped in the hand twice, put onehalf gallon water over them in a new coffee-pot kept for that purpose, boil slowly for one hour. Do not tie them in a cloth to boil, as that keeps the pollen (an important rising property) out of the yeast. Pare and grate half a dozen large potatoes into a two gallon stone crock, add a half cup sugar, table-spoon each of salt and ginger, pour over this a half gallon of the boiling hop-water, stirring all the time. When milk-warm, add one cup of good lively yeast, set in a warm place until it rises, and remove to the cellar or some other cool place. The boiling hop-water must be added to potatoes immediately or they will darken, and darken the yeast. A good way to prevent the potatoes from darkening is to grate them into a pan half filled with cold water. As grated the potatoes sink to the bottom; when done grating, pour off the water and add the boiling hop-water. This is an excellent recipe, and the method given for boiling hops is especially recommended.
A liquid hop-and-potato barm of the kind kept going from week to week in kitchens without access to packaged yeast. It works, but it behaves nothing like a modern sachet, and a few of the instructions carry more weight than they appear to.
- Add the hop water boiling hotThe hinge of the recipe. Grated raw potato darkens within minutes on exposure to air, and very hot liquid both cooks the starch and scalds the medium relatively clean. Pour it over while stirring, in a steady stream, not in one dump.
- Quantities in modern termsTwo handfuls of hop cones is a very rough measure; whole dried cones are light and bulky, so expect something under an ounce. Half a gallon is 2 quarts (about 1.9 L), and expect to lose a fair amount to evaporation over an hour of slow boiling, so start with a little extra or top up — the recipe still wants a full half gallon to pour over the potatoes. A two-gallon stone crock is about 7.5 L; any nonreactive vessel of that size with generous headroom will do, since the mix foams hard.
- The "new coffee-pot kept for that purpose"Hop resins are bitter, tenacious and will flavor anything else cooked in the pot afterward. Use a stainless or enameled saucepan you don't mind dedicating.
- Milk-warmBlood heat, roughly 95-100F. Yeast is stressed above about 110F and killed around 130-140F, so do not pitch into a mixture that is still hot. Give it time to fall on its own rather than chilling it fast, and check with a thermometer instead of a fingertip.
- "One cup of good lively yeast"The recipe assumes a running chain of barm from the last batch. Starting from nothing, seed it with a very active sourdough starter or a packet of commercial yeast bloomed first; the hops, sugar and potato are the food, not the leavening.
- Why the ginger and saltGinger appears in many nineteenth-century yeast recipes, where it was believed to encourage fermentation as well as correct the flavor; the hop resins do inhibit some competing bacteria. Neither ingredient is purely decorative.
- Keeping and using itThis makes roughly 2 quarts of liquid yeast. Refrigerated in a loosely covered jar it stays usable perhaps a week or two, souring as it goes. Reckon on about 1 cup per large batch of bread, with a long rise; it is far slower than commercial yeast and cannot be substituted spoon for spoon.
- When to throw it outA healthy barm smells beery and sharp. Pink, orange or fuzzy growth on the surface, or a putrid rather than sour smell, means it has been overtaken and the crock should be emptied and scalded.
Before packaged yeast was reliably available, many households kept leavening alive themselves, and hop yeast was one common method: hops for their preservative bitterness, potato and sugar for starch and food, ginger and salt for keeping quality. The chain depended on always saving a cup back from the last batch, which is why the recipe can casually call for "one cup of good lively yeast" as an ingredient. Commercial compressed yeast is generally traced to the American market of the late 1860s and after, but it spread slowly outside cities, and books like The Dixie Cook Book — a late-nineteenth-century compilation aimed at Southern households — still devoted a full section to making and maintaining your own. The insistence that the hops be boiled loose rather than tied in a bag reflects a widespread belief that the pollen itself carried the rising power; what the loose boil actually does is extract more resin from the cones.