This is really a jelly rather than a jam but if you don't mind seeds miss out the straining part. I also added extra pectin to ensure a set.
Ingredients
- 900g (2lbs) brambles/blackberries
- 150ml (1/4 pint) water
- Juice of 2 lemons
- White granulated or cane sugar
Instructions
Place the blackberries into a pan with the water and lemon juice, and simmer over a low heat until the blackberries are soft, pressing them all the time with the back of a wooden spoon.
Strain through a jelly bag, muslin or a clean tea towel over a bowl overnight. You can squeeze the fruit to extract more juice, but the jam will not be as clear.
The next day, measure the juice and weigh out 450g (1lb) sugar for every 600ml (1 pint) of liquid.
Place the juice and the sugar into a pan together and heat gently until the sugar has completely dissolved. Bring it all up to a rolling boil and allow to boil until setting point has been reached.**
Pour or ladle the jam into clean, hot and sterilised jars and seal immediately.
Add a label once the jars are cold and store in a dark, cool and dry place until needed.
Setting Point**
Flake test - dip a large spoon into the pan of jam and scoop out a spoonful - hold the spoon horizontally over the pan of jam and allow the jam to drip......setting point has been reached when the jam forms a long drip-like webbed feet, and hangs without dropping from the spoon.
Cold saucer test – Place two or three saucers into the freezer; spoon a spoonful of jam onto the cold saucer, and push it with your finger, setting point has been reached when the jam wrinkles and isn't runny.
Temperature test – Use a sugar thermometer and place the thermometer into a jug of boiling water just before testing for a set; lower the thermometer into the jam and setting point has been reached when the reading is 104.5C (220F)
https://www.lavenderandlovage.com/2018/08/preserving-the-season-seedless-blackberry-jam.html#mv-creation-1158-jtr
