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Grape Isinglass Jelly
Dissolve one ounce of isinglass or gelatine in a cupful of water. Put a pound and a half of ripe purple grapes into a saucepan. Bruise them with the back of a wooden spoon until the juice flows freely. Strain them, without pressure, through two or three thicknesses of muslin, and, when the juice is clear, boil it, with half a pound of loaf sugar and the dissolved isinglass, for ten minutes. Add two table-spoonfuls of brandy, pour it into an oiled mould, and put it into a cool place until firmly set. If the jelly is not clear, it may be clarified in the usual way. (See CALF'S FOOT JELLY.) Probable cost, 2s. 6d., exclusive of the brandy.
A simple set jelly from the era when clarity was the whole point of the exercise. Two things decide whether it works: how you strain the juice, and how you treat the gelatine.
- Do not boil the gelatine for ten minutesProlonged boiling can weaken gelatine's setting power. Boil the juice and sugar for the ten minutes, then take the pan off the heat and stir in the dissolved gelatine until it disappears.
- One ounce of isinglassThat is 28 g, roughly four 7 g sachets of powdered gelatine or about 14 leaves. It is a firm Victorian set, meant to be turned out of a mould and hold its shape; for a softer, spoonable jelly use half to two-thirds as much.
- Strain without pressureThe instruction is the hinge of the recipe. Squeezing the muslin pushes pulp and fine solids through and the jelly turns cloudy. Let it drip, and expect around 1½ cups of juice from 1½ lb of grapes.
- Loaf sugarRefined sugar sold in a cone or block, broken up for use. Ordinary granulated sugar is the same thing; half a pound is about 1 cup plus 2 tablespoons.
- The grapes"Ripe purple grapes" in a British book of this period would most likely have meant hothouse or imported dessert grapes with real acidity and colour, such as Black Hamburg. Concord or another slipskin gives good flavour and colour as a substitute; modern seedless supermarket grapes are sweet and mild, so add a squeeze of lemon.
- Brandy off the heatStir it in after the pan comes off the boil, as the recipe implies, so the aroma survives. Two tablespoons in this quantity is flavouring, not preservation.
- The oiled mouldBrush with a flavourless oil, then wipe almost dry — a film is enough to release the jelly and too much leaves a slick on the surface. Rinsing the mould with cold water works as well.
- "A cool place"The refrigerator. Allow four to six hours, or overnight for a mould you intend to turn out. To unmould, dip the mould briefly in warm water and invert.
- Yield and costAbout 2½ cups, serving four to six. The 2s. 6d. is a period price note, useful only as a reminder that grapes were a luxury item in a British kitchen.
Isinglass is a pure collagen gelatine prepared from the swim bladders of fish, principally sturgeon, and for centuries it was the setting and clarifying agent of the English kitchen and brewhouse alike. Cassell's offers "isinglass or gelatine" as interchangeable because by the later nineteenth century manufactured sheet and powdered gelatine, cheaper and made from bones and hides, was steadily displacing it; the older word lingered in recipes long after the older material left most larders. The cross-reference to calf's foot jelly points back to the still earlier practice of extracting gelatine at home by boiling down feet, a day's work that packaged isinglass abolished. Clear jellies of this sort were show pieces of the dessert table and also standard invalid cookery.