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Isinglass Jelly, Orange
To the juice of eight fine sweet oranges and four Seville, well strained, add an ounce and a half of isinglass dissolved in boiling water, sweeten with six ounces of pounded loaf sugar, and stir it gently over the fire, but do not let it boil. Pour the jelly into earthenware moulds when nearly cold, the moulds having been previously filled with cold water. Probable cost, 3s. ISINGLASS JELLY, ORANGE (another way). (See ORANGE ISINGLASS JELLY.)
A clear moulded fruit jelly of the sort that stood on Victorian supper tables, set with fish gelatine rather than sheet or powdered leaf. The whole thing hinges on heat: the setting agent must dissolve fully but the juice must never reach a boil.
- Isinglass, and what to use insteadIsinglass is collagen from the swim bladders of sturgeon and related fish, sold in shreds or leaves. It is now a specialist item used mainly for fining beer and wine; ordinary powdered or leaf gelatine will do the same work, though isinglass and gelatine differ in setting strength, so a weight-for-weight swap is only a starting point. 1½ oz is about 42 g, a generous amount for a firm turn-out jelly.
- Do not let it boilProlonged boiling weakens gelatine's setting power, and hard boiling also drives off the volatile oils that make orange jelly taste of orange. Warm the sweetened juice only until the sugar dissolves and the isinglass solution is thoroughly incorporated — the pan should steam, not bubble.
- Seville orangesThese are the bitter marmalade oranges, in season roughly January to February, and they are here for acidity and aroma rather than sweetness. If you cannot get them, use the juice of two more sweet oranges plus the juice of a lemon and a little grated orange zest.
- Quantity of juiceEight sweet and four Seville oranges yield somewhere around 600–700 ml (2½–3 cups) of juice depending on size. Measure the juice and adjust the gelatine proportionally rather than trusting the fruit count.
- Loaf sugarSugar was sold as a hard refined cone to be broken and pounded; "pounded loaf sugar" is simply granulated or caster sugar. Six ounces by weight is roughly ¾ to 1 cup, which reads sweet by modern taste against fresh juice — taste before setting.
- Strain properly"Well strained" means clear. Pass the juice through muslin or a fine sieve twice; pulp and membrane will cloud the jelly and settle as a scum at what becomes the top of the turned-out mould.
- The water in the mouldsFilling the moulds with cold water and tipping it out leaves them wet, which helps release the set jelly cleanly. Earthenware was a common household mould material; a metal or silicone mould works, rinsed the same way.
- Setting and yieldPour when nearly cold, then refrigerate at least 4 to 6 hours, or overnight for a large mould. With the water used to dissolve the isinglass, this makes roughly 800 ml to a litre of jelly, serving six to eight.
Isinglass reached British kitchens as an import, much of it from Russian sturgeon fisheries, and it was valued both as a setting agent and as a fining agent for clearing wine and beer — the same protein still used by some brewers. Before commercially packaged gelatine became cheap and reliable in the later nineteenth century, a cook wanting a clear jelly either boiled down calves' feet for hours or bought isinglass, and isinglass was the cleaner-tasting of the two. Moulded jellies were a test of technique rather than of ingredients: the skill lay in judging strength, keeping the mixture below a boil, and achieving a jelly transparent enough to see through. The "probable cost, 3s." is characteristic of the book, which priced dishes so a household could budget; three shillings was not a trifling sum, and a dozen oranges plus imported isinglass made this a jelly for a company table rather than a family one.