Plum Paste
For this use tart but juicy plums and cook in their own juice until soft. Remove stones and press pulp through sieve; weigh, and replace on stove. Allow and set aside half this weight in sugar. Cook pulp slowly an hour before adding sugar; let latter dissolve and boil one minute. Pour the mass into earthen dishes in quarter-inch thickness, and dry slowly in cool oven. Remove and pack away for use in ornamenting puddings or cakes or to dilute and serve as sauce.
This is a fruit paste in the old confectioner's sense — a stiff, sliceable sheet of concentrated plum, closer to quince paste or a fruit leather than to jam. The whole recipe hinges on driving off water before the sugar goes in.
- The hinge: reduce first, sweeten secondThe hour of slow cooking before the sugar is the recipe. Sugar added early raises the boiling point and holds water in a syrup that is far harder to dry down to a paste; once the pulp has thickened, stir in the sugar, dissolve it and give it the single minute of boiling the recipe calls for.
- Weighing the pulp"Half this weight in sugar" means 50 percent by weight — 1 lb sieved pulp to 8 oz sugar. Weigh the pulp in the pan, deducting the pan's tare, rather than guessing by volume.
- Which plumsTart, juicy varieties work best: damsons, Italian prunes, greengages, or any underripe supermarket plum. Very sweet dessert plums give a flabby paste with no acid backbone, and pectin tends to run higher in fruit that is just short of fully ripe. Since the stones come out after cooking, it makes no difference whether the fruit is freestone or clingstone.
- Cooking in their own juiceHalve the plums and start them over low heat. The recipe wants no added liquid at all; if the pan is dry at the outset, a spoonful of water will keep the first layer from scorching, though it must then be cooked back off. A heavy-bottomed pan and frequent stirring matter more here than any timing, since thickened fruit puree catches quickly.
- "Cool oven"The book does not define the term; for drying rather than baking, the lowest setting the oven will hold, with the door propped ajar so moisture escapes. A dehydrator at 135-150F does the same job more evenly. Drying a quarter-inch layer is a matter of hours rather than minutes, and depends on how far the pulp was reduced.
- Earthen dishesGlazed earthenware or shallow ceramic dishes; a rimmed baking sheet lined with parchment or a silicone mat is the modern equivalent and releases far better. Oil the surface lightly if you use bare crockery.
- Knowing when it is doneThe sheet should be leathery and tacky-dry, peeling away cleanly with no wet spots. Slightly underdried paste will weep and mould in storage — dry it a little further than seems necessary.
- Storage and yieldWeigh the pulp at the point the recipe says to, straight after sieving; 2 lb of plums will yield well over a pound of pulp before the hour of reduction. Cut the finished sheet into strips or squares, dust lightly with sugar or layer with parchment, and keep in an airtight tin; refrigerated it holds for months. To use as sauce, melt a piece with a little water or wine over low heat.
Fruit pastes of this kind are among the oldest forms of fruit preserving after drying whole: boil the pulp down, sweeten it, and dry it into a solid that keeps without a sealed jar. Medieval and early modern English kitchens knew such quince preparations as "marmalade" in the original sense -- the Portuguese marmelada was a firm quince paste, not a spreadable jelly -- and the tradition survives today in Spanish membrillo and in the plum and apricot pastes of Central Europe and the Levant. A paste of this sort needed no jars, no rubber rings and no processing kettle, and it gave the cook a concentrated fruit flavouring to hand for puddings and cakes all winter. The instruction to "dilute and serve as sauce" points to the older habit of storing preserves dense on purpose and thinning them back at the point of use.