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Fruit Isinglass Jelly
Get the juice from China oranges and a little lemon-juice or Seville orange juice, about a quart in all--of the latter, however, only enough to give a pleasant sharpness. Strain the juice through a double muslin bag, and again through a double muslin bag, and again through a flannel one. Have ready, in an enamelled saucepan, one ounce and a half of the best isinglass, dissolved in a little water; stir in half a pound of finely-sifted sugar and a few bits of the orange-rind, and simmer and skim, but do not let the liquid boil; add the juice and simmer again; then strain through muslin, made thick by being doubled three or four times. When nearly cold, fill moulds with the jelly. It should be quite clear when turned out. If it is not so, it may be clarified according to directions already given. (See CALF'S FOOT JELLY.)
A clear moulded orange jelly of the type Victorian kitchens served to invalids and at supper tables alike. The technique is entirely about clarity: every step exists to keep the finished jelly transparent enough to read through.
- Never let it boilProlonged or hard boiling can weaken isinglass and gelatin and will cloud the liquid, and boiled citrus juice loses its fresh edge for a cooked, flat one. Hold the pan at a bare shiver, skim, and pull it off the heat.
- China orangesOrdinary sweet oranges — the name distinguished them from the bitter Seville. Sevilles are seasonal (roughly January to February) and sharply bitter; lemon juice is the stated alternative and works perfectly well.
- IsinglassDried sturgeon swim bladder, once the premium setting agent and now sold mainly to brewers and wine makers for fining. Powdered or leaf gelatin is the practical substitute, but strengths are not equivalent and no honest one-to-one conversion exists; for a jelly of this size that must stand unmoulded, around 1 oz (four US envelopes) of powdered gelatin is a sensible starting point, tested on a chilled saucer.
- A quart of juiceIn a British book of this period, an imperial quart — 40 fl oz, or about 5 US cups. That is roughly 12 to 16 oranges depending on size.
- The enamelled panNot decorative advice. Acidic citrus juice can react with bare copper or cast iron, taking on a metallic taste and a grey cast. Stainless steel or enamel are the safe choices.
- StrainingThe muslin and flannel bags are doing the work of a modern jelly bag. Let it drip; squeezing forces pulp through and clouds the result. A coffee filter or several layers of damp cheesecloth in a sieve does the same job.
- Filling the moulds"Nearly cold" appears to mean cooled until the jelly has begun to thicken but will still pour. Pouring it hot lets any remaining sediment settle in the bottom of the mould, which becomes the top of the turned-out jelly.
- Setting and turning outSix hours in the refrigerator, better overnight. Dip the mould to the rim in warm — not hot — water for five seconds, then invert onto a wetted plate so the jelly can be slid into position.
- YieldSomewhere between a quart and a quart and a half of finished jelly; eight to ten servings from a single large mould.
Isinglass reached Britain largely from Russia, prepared from the swim bladders of sturgeon, and for most of the eighteenth and nineteenth centuries it was the clearest and most reliable setting agent a cook could buy — cleaner in flavour than the calf's-foot jelly it competed with, and far less labour, since calf's foot required hours of boiling and skimming before the jelly stage even began. Cheap commercial gelatin, sold in packets from the middle of the nineteenth century onward, eventually pushed isinglass out of domestic kitchens entirely; it survives today chiefly as a fining agent in cask ale and some wines, which is why traditionally fined beer is not vegetarian. Clear fruit jellies of this kind were valued as much for appearance as flavour, and were also standard sickroom food, the transparency taken as evidence that nothing heavy or indigestible remained in them.