No. 3410

Ferment

Wash seventeen quarts of small potatoes, put them into an enameled iron pot, pouring over sufficient cold water to cover; place the pot on the fire, and let them boil uninterruptedly until well done, then remove. Throw the potatoes into a large tub, add two and a half pounds of flour, mash well together with a pestle to reduce the whole to a smooth paste, then dilute this paste gradually with twenty-two quarts of water, either cold or barely lukewarm, according to the temperature and season; afterward add five quarts of yeast, and mix the whole well together. Cover the tub with a cloth, and set in a moderately warm place where there is no danger of its being disturbed and leave it until fermentation takes place, which means until it rises to double its height and falls again to its normal state. The fermentation should take place in from seven to eight hours. With this quantity of ferment a barrel of flour can be used.

← No. 3409 Yeast Bakery & Breads No. 3411 Leaven →

For the Modern Kitchen

This is not a bread recipe but a bakery-scale preferment, sized to leaven a full barrel of flour. Everything about it needs rescaling before it is of any use in a domestic kitchen.

The hinge: catch it at the fallThe ferment is ready not when it rises but when it has risen to double and dropped back. Used before the collapse it is under-strength; left much past it, the mixture sours and thins and will drag on the dough.
Yield and what a barrel meansA US flour barrel is 196 lb. The volume of the finished ferment can only be estimated: twenty-two quarts of water and five of yeast come to twenty-seven quarts before the mash from seventeen quarts of potatoes is counted in, so the working ratio is very roughly one quart of ferment to five or six pounds of flour.
Scaling downDivide by forty and you get about 1 lb small potatoes, 1 oz flour, a generous pint of water (a little over half a quart) and about half a cup of yeast, enough for around 5 lb of bread flour. The proportions hold; the timing does not scale, since a small tub loses heat far faster than a large one.
"Five quarts of yeast"This means the liquid barm of the preceding entry (No. 3409), not modern granulated or instant yeast. There is no honest conversion: a quart of barm is mostly water. If substituting, treat the potato mash and water as a straightforward potato preferment and inoculate with a very small quantity of commercial yeast, then judge readiness by the rise-and-fall.
Enameled iron, and whyBare cast iron can discolor potatoes and the starchy water. Any non-reactive pot serves.
Water temperature"Cold or barely lukewarm, according to the temperature and season" suggests the aim is the temperature of the finished mass rather than of the water itself, since the potatoes go in hot. The recipe gives no figures; a moderately warm mixture is what the seven to eight hours assumes, and a cold one will take longer.
Why potatoesCooked potato starch is readily converted, and potato ferments were reputed to stay sweeter than a straight flour-and-water sponge. The mash also holds warmth, which would matter in an unheated bakehouse.
Keep it clean and keep it movingA warm, slack, starchy mash held at room temperature is hospitable to more than yeast. In hot weather these ferments turn sour or go slimy and stringy. Make what will be used the same day, scald the tub between batches, and discard anything that smells cheesy or drawn out into threads.

A Little History

Charles Ranhofer's The Epicurean (1894) records the working practice of the Delmonico's kitchens, and the bread chapter is written for a professional bakeshop turning out loaves by the barrel of flour rather than the loaf. Before compressed yeast became cheap and reliably available in the later nineteenth century, bakers commonly kept their own leaven alive in stages, and potato ferments of this kind were one such first stage: boiled potatoes and a little flour gave the yeast an easy, sugar-rich medium in which to multiply from a small inoculum into enough active barm to raise a very large mass of dough. The sequence of entries here, yeast, then ferment, then leaven, reads as a chain, each feeding the next. It is worth noticing that this preferment carries no salt and no shaping instructions; it was a raw material of the bakery, made in a tub in a warm corner.