Rhubarb and blueberry jam

Method

Place rhubarb and water in a large heavy-based pan. Boil gently for 10 minutes.
Add blueberries and sugar, stir to dissolve, and boil until setting point is reached.
Cool, pour into clean jars and seal.

Tests for setting point
Preserves are ready to place in the jar when they reach the stage of gelling or setting on cooling. Remove preserve from the element while the test is being carried out to stop overcooking occurring. To decide on the setting point, use one or more of the following tests:

Flake test:
Allow some of the preserve to drip from the spoon. When it no longer runs off the spoon in separate streams or drops, but falls as a U-shaped drip, the preserve will set on cooling.

Plate test:
Spoon a little of the preserve onto a cold plate and leave to cool slightly. If the sample forms a skin which wrinkles when the preserve is tipped, or touched with a teaspoon, it will set on cooling.

Adapted from the University of Otago, 1988, booklet, Jams, jellies, pickles and relishes, page 9.