Plum Ices
Crack half the kernels and bruise the pits, boiling them in the syrup or hot milk to extract the flavour, then strain. With damsons use no pits. Then proceed as for general directions in Introductory Recipes.
This is a flavouring instruction rather than a full recipe, and the flavouring it calls for is the one part of the plum that should not go into food. The points below explain the hazard and the gaps in the text.
- The kernels are the problemPlum stones, like those of apricots, peaches and cherries, contain the cyanogenic glycoside amygdalin. Crushed and wetted, they release hydrogen cyanide, which is exactly the process this recipe sets in motion when it tells you to crack and bruise them into hot syrup or milk.
- Heating does not make it safeHeating is not a reliable safeguard -- straining removes the solids but not what has dissolved into the liquid. Some hydrogen cyanide is volatile and will be lost in open boiling, but the recipe gives no times or quantities, and there is no domestic way to judge how much has passed into the syrup or milk.
- No quantity is given"half the kernels" is measured against a batch of plums the recipe never specifies. The risk depends on the number of kernels relative to the volume of syrup, and neither figure appears in the text, so the dose cannot be worked out.
- The damson line is not a safety note"With damsons use no pits" gives no reason at all. Damson kernels are as cyanogenic as any other plum kernel, so the omission cannot be read as a warning; why the author excluded them is not stated.
- The recipe is incomplete anywayEverything else, sugar, dairy, proportions and freezing, is deferred to the book's Introductory Recipes, which do not appear on this page. There is no yield, no churn time and no base formula here.
- If you want the flavourThe almond note this is reaching for is the same one sold today as almond extract, made from benzaldehyde. Use a current ice cream recipe and flavour the base that way.
Kernel flavouring belongs to the long European tradition of noyau, from the French for stone or kernel, in which cracked apricot, peach or plum kernels were steeped in spirit, cream or syrup to lend a bitter-almond perfume to cordials, custards and ices. Nineteenth-century cookery writers used the technique freely and confectioners prized it, because before synthetic benzaldehyde was widely available the routes to that flavour were bitter almonds, the stones of stone fruit, or leaves such as peach and cherry laurel -- all of them cyanogenic. Why the author omitted damson stones is not recorded. Fruit ices themselves were a mark of an ambitious household in this period: an ice needed a packed ice-and-salt freezer and a good deal of arm work.