Ingredients
Method
- Place blackberries (straight from frozen if using frozen) and lemon juice in a large preserving pan. Heat over medium heat 15–20 minutes until completely broken down into a thick, seedy purée.
- Strain half the pulp through a fine sieve — press firmly to extract juice and soft pulp, discarding seeds. Return strained juice to pan with remaining unstrained pulp. Stir.
- Add warm sugar — stir continuously over medium heat until every grain has dissolved.
- Increase heat — bring to a vigorous rolling boil. Boil 8–15 minutes. Test for set at 8 minutes using wrinkle test or thermometer (104–105°C). Boil and test until setting point reached.
- Remove from heat. Skim foam. Stand 5 minutes — stir gently. Ladle into warm sterilised jars. Seal immediately. Label and store.
Notes
Strain half the pulp — gives the ideal texture: jewel-dark jelly with suspended whole berry pieces.
Lemon juice is essential — blackberries are low in pectin and will not set reliably without it.
Warm the sugar before adding — dissolves faster and reduces total boiling time.
Test for set from 8 minutes — blackberry jam sets quickly and can easily be over-boiled.
Wild hedgerow blackberries in late August give the finest possible jam if available.
Sealed jars keep 12 months. Opened jars refrigerate for 6 weeks.
