Prune Tarts
Scald the prunes, take out the stones, break them and put the kernels in a little cranberry juice with the prunes, and some sugar. Simmer them, and when cold put in tart shapes in pastry and bake.--Mrs. V. P. M.
The filling here depends on cracking the prune stones and cooking the kernels inside with the fruit. That single step is why this one belongs on the shelf rather than in the oven.
- The kernels are the problemPrune and plum stones enclose a kernel that carries amygdalin, a cyanogenic glycoside — the same class of compound that makes bitter almonds dangerous. Crushed and moistened, the kernel's own enzymes release hydrogen cyanide, and simmering a pan of them in juice does not reliably drive it off.
- No way to judge the doseThe recipe names no quantity of prunes, so there is no way to know how many kernels go into a batch, and amygdalin content varies with variety and ripeness. A flavouring used in drops is one thing; a tart filling built on a bowl of cracked stones is not a measurable amount.
- Why it was doneThe kernel was prized for a bitter-almond, marzipan-like note, and period recipes call for it freely with no hint of a hazard. The perfume and the toxin arise from the breakdown of the same compound, which is precisely the difficulty.
- Not an ordinary kitchen riskThis is not hot fat or a sharp knife. If you want prune tarts, use a current recipe that stones the fruit and discards the pits, and take the almond note from almond extract or a splash of amaretto instead.
- On "tart shapes"For context only: the phrase most likely means the small shallow tins or patty pans of the period, lined with pastry — what a modern cook would call tartlet moulds rather than a single large tart.
Housekeeping in Old Virginia, compiled by Marion Cabell Tyree and first published in 1878 (with later printings), gathered contributions from named Virginia housekeepers — here "Mrs. V. P. M." Cracking stones for their kernels was common in European and American cookery well into the nineteenth century: the same instinct produced ratafia and noyau, cordials flavoured with cherry or peach kernels, and it persisted in almond-scented puddings and jams. The chemistry of amygdalin was described by French chemists in the 1830s, but household understanding that cracked stone-fruit kernels were anything worse than pleasantly bitter came later, which is why a recipe like this could sit unremarked in a respectable domestic manual. The cranberry juice is an American touch.