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Vegetable Marrow Preserve
Peel the marrows, remove all the seeds, cut the marrows in pieces the size of large plums, boil them with their weight in sugar till the pieces become transparent. No water whatever is required. Then flavour with ginger and lemon, or ginger or lemon, according to taste.
A two-ingredient preserve that depends entirely on drawing the marrow's own water out with sugar. The instruction that matters is the one most easily ignored: no water at all goes into the pan.
- What a vegetable marrow isA marrow is a summer squash left on the plant to grow large and mature, with a firm rind and developed seeds. The closest supermarket substitute is the biggest, oldest zucchini you can find, or a pale green cucuzza-type squash from a farm stand. Young courgettes are too watery and will collapse rather than turn translucent.
- Equal weight of sugarWeigh the peeled, seeded, cut flesh and match it with granulated sugar, as the recipe directs. A preserve at this ratio, boiled down until the syrup is heavy, keeps largely on sugar concentration; how well it keeps depends on how far it is reduced.
- Let it stand before heatingSince no water is added, the pan needs the marrow's juice to start. Layer the pieces with the sugar and leave them covered for several hours or overnight; a syrup will form on its own. Heating a dry pan of sugar and squash straight away scorches the bottom.
- "Transparent" is the doneness cueThe pieces go from opaque white-green to glassy amber, and the syrup thickens. Expect 45 minutes to well over an hour depending on the age of the marrow. A jam thermometer reading 220F/105C in the syrup is a reliable second check.
- Marrow has almost no pectinThis sets soft, more like a candied fruit in heavy syrup than a firm jam. Lemon adds acid and a little pectin alongside its flavour, though the original leaves the choice open: ginger alone is one of the options it offers.
- How to use the gingerBruised fresh root tied in muslin and fished out at the end gives clean heat; chopped crystallised ginger, about 2 oz per 2 lb of fruit, gives sweetness and visible pieces. Ground ginger will cloud the syrup.
- Yield and storageTwo pounds of prepared marrow plus two pounds of sugar fills roughly six 8 oz jars. Pot hot into clean hot jars and seal; refrigerate once opened.
The marrow was a glut crop in Victorian and Edwardian kitchen gardens, and a single plant could produce more squash than any family wanted to eat as a boiled vegetable. Marrow flesh is bland and nearly neutral, which made it a useful carrier for other flavourings, and preserves of this kind were frequently sharpened with lemon or ginger, or with the pips and peel of citrus, so that the result read as a fruit conserve. The related trick of colouring and flavouring marrow to imitate more costly fruits is a long-standing British domestic habit, and marrow-and-ginger jam remains a fixture of allotment cookery today. The absence of added water is not thrift alone: sugar draws liquid from the cell walls by osmosis, and the resulting concentrated syrup is what turns the pieces translucent and keeps them from fermenting.