250gm caster sugar
10 blood oranges
Preheat the oven to 100oC. Wash two 250ml jam jars and their lids in hot soapy water and rinse, then transfer jars to the oven and leave to dry for 10 minutes. After 10 minutes turn the oven off and allow jars to cool. Wet a piece of kitchen towel in methylated sprits and clean the lids. This sterilizes the jars, preventing mould from forming.
Zest and juice the oranges and lemons. Wrap lemon seeds in muslin bag and tie shut with string ensuring you leave it long enough to wrap around the handle of the saucepan to allow it to be lifted out when it is no longer required. Place two saucers in the freezer. These saucers will be used to conduct a gel test to establish whether or not the marmalade is thick enough.
Place orange zest and juice in a saucepan with sugar and lemon juice, stir until sugar is dissolve then add the muslin bag containing lemon seeds. Simmer for 30-35 minutes, brushing down the sides with a damp pastry brush and spooning any scum off the surface. Though it may be tempting, do not stir the liquid once the sugar has melted into the juice as this causes sugar crystals to form giving the final product a grainy texture. This said you can occasionally swirl the saucepan.
Once the 35 minutes have passed, remove a saucer from the freezer and take the saucepan off the heat removing the muslin bag and conduct a gel test. This involves placing a teaspoon of marmalade onto the chilled saucer, allowing it to stand for 1-2 minutes then slowly running your index finger through the mixture. If the surface of the marmalade wrinkles as though it has a skin on it then this indicates that it has reduced enough and will set in a spreadable consistency. If it is not thick enough return to the heat for a further five minutes.
When the marmalade is ready remove the muslin bag from the saucepan and discard. Take out the jars from the oven using tongs or your hands (if you do this by hand ensure not to touch the inside of the now sterilized jars). Using a jam funnel or a steady hand pour the contents of the saucepan into the jars and seal with the lids immediately. As the marmalade and air in the jar cool it will form a part vacuum causing the lid to concave slightly. When you open the cooled marmalade the lid will ‘pop’ open s a result of the vacuum being broken - this is the same sound you hear when you buy store bought jams. Once cooled the jars can be labelled.