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Mixed Jam
Boil together any quantity or kind of fruit--currants, gooseberries, cherries, or plums--with or without the stones, for half an hour; then add to every pound half a pound of moist sugar, and boil another half hour. It is an excellent jam for the nursery. We would recommend that all fruit should be stoned. Mixed jam will keep six months.
A thrift recipe rather than a formula: whatever fruit is ripe at once, boiled down together. The proportions and the timings both need rethinking before you commit a preserving pan to it.
- Cook to a set, not to a clockModern practice is to boil to setting point, 220F/105C, or to test a spoonful on a chilled saucer; much mixed fruit will reach it well before the hour the recipe specifies. The extra boiling costs you colour, fresh flavour and a good deal of pectin.
- Moist sugar"Moist sugar" is unrefined or partly refined soft sugar, closest to today's light brown soft sugar. Granulated or preserving sugar gives a cleaner, brighter jam; brown sugar will darken the fruit and add a faint molasses note, which is authentic but not to everyone's taste.
- The sugar ratio is lowHalf a pound of sugar to a pound of fruit is about a third of the weight going into the pan, below the roughly 60 to 65 per cent soluble solids usually reckoned to make a preserve keep on its own, and how far the finished jam concentrates depends on how long you boil it. Standard modern proportions are equal weights of fruit and sugar, or three-quarters at the least.
- Six months is optimisticAt this sugar level, and with no instruction to sterilise jars or seal them, the jam will grow surface mould in a cupboard. Fill sterilised jars boiling hot and seal at once, then treat it as a refrigerator jam once opened, or process filled jars in a boiling-water bath following current guidance.
- Stone the fruit, as the book saysCassell's own aside is the important line. Plum and cherry stones contain amygdalin, which releases hydrogen cyanide when the kernel is crushed or steeped; whole stones in a jam are also a dental hazard and make the preserve impossible to spread. Stone everything before it goes in the pan.
- Balance the pectinCurrants and gooseberries are high in pectin and acid; cherries are low in both, and dessert plums vary, though damsons and cooking plums are well supplied. A mixture weighted towards cherries may not set. Include a good proportion of currants or gooseberries, or add the juice of a lemon per two pounds of fruit.
- YieldThe yield depends on how far you boil it, and will be appreciably less than the combined weight of fruit and sugar. Skim the scum before potting or the surface will look cloudy.
Mixed jam was a way of using up the odd pounds left over at the end of a picking, or the fruit too bruised to be worth potting on its own. The frank note that it is "an excellent jam for the nursery" tells us only that the mixture was thought good enough for the children's table rather than a showpiece preserve. Jam-making on this scale became a middle- and working-class habit in Britain in the second half of the nineteenth century, after the sugar duties were reduced and finally repealed in 1874 and cheap refined sugar came within reach of ordinary kitchens; the commercial jam trade grew out of the same conditions. The low sugar proportion here, and the modest six-month claim that goes with it, reflect a cook still treating sugar as something to be used sparingly.