Cakes
Blackberry jam
Making a batch of blackberry jam is a wonderful way to bottle the last of summer’s warmth. A sugar thermometer guarantees a good set, but if you don’t have one, you can use the traditional method of testing for set on a chilled plate.
Ingredients for Blackberry jam
- 1.2kg/2lb 10oz blackberries
- 700g/1lb 9oz caster sugar
- 1 lemon, juice only
Method
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If you don’t have a sugar thermometer, a few hours before you want to make your jam, put a couple of small plates or saucers into your freezer.
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Wash the blackberries and add to a large, heavy-bottomed saucepan. Cook over a medium–high heat for 8–10 minutes, stirring occasionally, until most of the blackberries have broken down and the remaining berries are almost submerged in their juice.
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Begin to add the sugar to the berries, a third at a time, stirring between each addition, then add the lemon juice. Bring the mixture to the boil, then turn the heat down slightly to a gentle rolling boil and simmer for 8–10 minutes, until the jam reaches 105C/220F on a sugar thermometer. At this stage the bubbles in the jam will have changed from large to small, indicating that most of the water from the fruit has evaporated.
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If you don’t have a sugar thermometer, you can test if your jam has reached setting point using your pre-chilled plates. When you’re ready to test the set, remove a plate from the freezer and drop a teaspoon of jam onto it. Leave it for a moment, then run your finger through the jam. If the jam crinkles a little on the surface as though it’s beginning to form a skin, it’s ready to be jarred. If the jam remains runny and the line your finger has created disappears in the jam, cook it for a few more minutes and test again with your second chilled plate.
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Carefully divide the jam between six warm sterilised jars and seal with sterilised lids. The jam will keep, unopened, in a cool dark place for 12 months. Once open, store in the fridge and eat within two weeks.
Blackberry jam