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Raspberry Jam
Measure the berries before putting into the kettle, with a small amount of water; cook until tender; then add one pint of sugar to one of berries; cook ten minutes.
A bare-bones jam formula of the sort that assumed the cook already knew what jam looked like when it was done. The proportions are sound; the timings and the silence on sealing are what need attention.
- Measure by volume, not weight"One pint of sugar to one of berries" means volume for volume: a pint of raspberries is roughly 12 oz, a pint of granulated sugar roughly 14 oz. That is close to the classic equal-weight ratio and will set and keep well.
- The kettleA preserving kettle is a wide, heavy, unlined-copper or enamelled pan, not a modern tea kettle. Use the widest heavy-bottomed pot you have; surface area drives evaporation and shortens the cooking time.
- "A small amount of water"A quarter cup for two pints of berries is enough to keep them from scorching before their own juice runs. Raspberries are wet fruit and more water only means more boiling later.
- Ten minutes is a starting pointTen minutes of hard boil after the sugar dissolves gets most raspberry jam to the gel point, but it depends on your pan and the ripeness of the fruit. Test at 220F on a thermometer, or chill a spoonful on a cold saucer and push it with a finger; it should wrinkle.
- No added pectin neededRaspberries carry moderate pectin and good acidity, which is why this recipe gets away with no lemon and no commercial pectin. Very ripe fruit sets more loosely; a squeeze of lemon juice compensates.
- Seeds and scumSkim the pink foam once the boil is established or the finished jam looks cloudy. If you want it seedless, press half the cooked fruit through a fine sieve before the sugar goes in.
- Storage, which the recipe omitsThis is a cooking method, not a canning procedure. Refrigerate the jam and use it within a month, or follow current water-bath processing guidance for jars and times if you intend to store it on a shelf.
- YieldTwo pints of berries with two pints of sugar gives roughly four half-pint jars, depending on how far the jam is boiled down.
Raspberry jam is one of the plainest entries in any preserves chapter: raspberries bruise quickly after picking and, before refrigeration, a household with canes in the garden had good reason to turn the crop into something shelf-stable promptly. A roughly one-to-one sugar ratio was a common nineteenth-century preserving proportion, arrived at empirically long before anyone described pectin chemistry. Sugar binds enough water to inhibit mould and yeast, which is why high-sugar jams keep at room temperature and low-sugar ones generally will not. Turn-of-the-century American cookbooks often gave preserves in this telegraphic style, measuring fruit by the pint rather than the pound.