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Yeast, Preserved
When yeast is plentiful, take a quantity and work it well with a whisk until it becomes thin; then procure a large wooden dish or platter, clean and dry, and with a soft brush lay a thin layer of yeast on the dish, and turn the top downwards to keep out the dust, but not the air; this is to dry it. When the first coat is dry, lay on another, and let that dry, and so continue till the quantity is sufficient; by this means it may soon be made two or three inches thick, when it may be preserved in dry tin canisters or stoppered bottles for a long time. When used for baking, cut a piece off, and dissolve it in warm water, when it will be fit for use.
This is a method for turning liquid brewer's barm into a dry, storable leaven — the Victorian household's answer to the packet of dried yeast. It works, but the assumptions behind it need translating.
- What "yeast" means hereNot a dry granule but barm — the frothy, cream-to-batter-thick liquid skimmed from fermenting beer, or a wet baker's yeast bought by the pint. If you want to try the method, the modern stand-in is a wet, active sourdough starter or a fresh cake yeast slurry; commercial dried yeast is already dried and needs nothing done to it.
- The hinge: thin coats, fast dryingEverything depends on each layer drying quickly enough that spoilage organisms cannot get established in the damp film. Brush the layers no thicker than paint and let each dry fully before the next. Thick, slow-drying coats sour and go off rather than preserve.
- Heat kills itThere is no oven step for a reason. Yeast is damaged by heat: it begins to suffer somewhere above about 120F and is finished by around 140F, so drying must happen at cool room temperature in moving air. A dehydrator set to its lowest setting, or a fan and an uncovered tray in a dry room, does the same job as the inverted wooden platter.
- Why the dish is turned face downThe instruction to invert it "to keep out the dust, but not the air" is the whole ventilation strategy: airflow underneath, no debris settling on a sticky surface. A raised cake rack over parchment achieves it more easily than a platter.
- Wood, then and nowA large wooden platter was what a Victorian kitchen had to hand; the recipe asks only that it be clean and dry. Modern equivalents are silicone mats or baking parchment.
- Quantity and strength are unknowable"A quantity" and "two or three inches thick" give no yield, and the raising power of dried barm varies enormously with how alive it was to begin with. Treat any piece you cut off as an unknown and proof it in warm water — about 100F — for fifteen minutes to see whether it foams before committing it to a batch of dough.
- Storage reality'A long time' probably meant weeks to a few months in a cool, genuinely dry larder; the recipe gives no figure. Viability falls steadily; keep it airtight in a cool dark place, or refrigerated, and expect longer rises and eventual failure rather than a clean cut-off.
Before packaged yeast, leaven was a by-product of brewing, and its supply rose and fell with the brewer's calendar — hence the opening phrase, "when yeast is plentiful." Households and small bakers bought barm by the pint, and it kept only days, so drying it into cakes or sheets was a standard hedge against the weeks when none was to be had; the same impulse produced hop-and-potato yeast cakes. Cassell's was compiled at exactly the moment this was becoming optional: pressed compressed yeast, made in dedicated factories rather than skimmed off beer, was spreading through Britain in the last quarter of the nineteenth century and would shortly make the whole exercise a curiosity. A Victorian cook was expected to understand her leaven as a living material to be managed, not an ingredient to be bought.