Rinse and clean the jostaberries. Rinse and coarsely grate zucchini. Put everything in a high saucepan. Add raspberries and citric acid.
Stir the gelling aid with the sugar and add to the fruit form. Mix well and bring to a boil, stirring throughout. Make it bubble for 1 minute. Skim, make jelly test and pour into prepared, thoroughly cleaned twist-off jars. Close jars tightly, invert on lids for 5 min. Invert and cool.
Gelation test: put a small amount of jam on a cold plate, if it does not set on the spot, bring to the boil again briefly.
Tip: Zucchini are a type of pumpkin and therefore low in calories, rich in vitamins and easy to digest – just the thing for a light meal!