I adore plum jam and it’s very easy to make. This recipe yields around 4-5 jars of lovely rich red jam for relatively little effort.
Plums are reasonably high in pectin, which is essential for your jam to set. Citrus fruits also have a high pectin level so the addition of a squeeze of lemon juice will not only brighten the flavour but help the jam to gel.
A preserving pan is designed with sloping sides to aid evaporation when bottling and preserving but is not essential. A large 6 litre, heavy based stock or soup pot will work as well.
- 1 kilo of ripe clean, red fleshed plums
- 200ml water
- 1 kilo sugar
- 2 tbsp lemon juice
- clean jars and lids
Halve the plums by slicing around the natural crease, twist the halves to separate and remove the stones.
Place the prepared fruit and water into a large heavy preserving pan or 6 litre stock pot. Simmer gently until the fruit begins to soften. Add the sugar and lemon juice, stirring until sugar is completely dissolved.
Boil the jam for around 20—30 minutes, stirring frequently to ensure it doesn't stick and burn. Keep and eye on it as when it first boils it will rise high up the pan, as the fruit cooks down it'll boil with less drama.
If a large amount of scum builds up when the jam is boiling skim it off with a metal spoon.
While the jam is boiling place 3 small plates into the freezer. After around 20-25 minutes you can start testing for a set. To do this drop a teaspoonful of hot jam onto a chilled plate, leave for one minute then push with your fingertip, the jam should wrinkle on the plate. If it only wrinkles a little continue to boil for another 2 minutes and test again. You may need to test a number of times so return the plates to the freezer to keep them cold.
While the jam is cooking prepare the jars by sterilizing in the oven. Preheat the oven to 120°C; place the jars in the oven at least 20 minutes before you need them. Place the lids in a small saucepan of boiling water and boil for 10 minutes.
When you have a "set"- the jam wrinkles when pushed, use tongs to remove a hot jar from the oven, place it into a heatproof dish (to catch spills) fill to the top with hot jam and use the tongs to pick up a hot lid from the saucepan and screw it on.
When the jam is cooled it will be well set, the hot jars and lids will have formed a vacuum so the lids will invert slightly and will give a satisfying pop when you come to open them. Just like the bought ones -only better.
If you are worried about getting your jam to set you can use "jam setting sugar" which has added pectin in it. It makes a reliable jam quickly but rather takes the adventure out of it.