This is how you make the most delicious jam: Mix 1 kg of cleaned, fresh, ripe and pureed fruit with 1 kg of Gilse jellysugar. For pectin-poor fruit (such as strawberries, grapes, raspberries), use 900 fruits instead of 1 kg and add the juice of half a lemon. Bring the mixture to the boil in a large, high pan, while stirring. Let the mixture boil for 4 minutes. Fill the glass jars to the top with the hot (still thin) jam. Close the jars and put them upside down for 5 minutes. Store the jam in a cool, dark place.