Wash the currants and remove the stalk. Drain well. Put in a saucepan and crush with a potato masher. Add the water, bring to the boil and simmer for about 20 minutes.
Filter the pulp through a cloth. The juice obtained is weighed or measured and mixed with the sugar. For 1 kg (1 liter) of juice you can count a maximum of 650 g of sugar.
Bring the juice with the sugar to a boil over high heat and then skim it off. Stir the preserving aid into the juice that is no longer boiling. Fill the hot juice into bottles and close them immediately.