Wash and then drain the chokeberries. Prepare a sugar syrup of water and sugar and once it thickens slightly, drop the chokeberries in it.
Optionally, add 1 cinnamon stick and lemon zest. Cook until the jam thickens. Finally, add pectin, stir for 2-3 minutes and remove from the heat.
Put the chokeberry jam in warm and dry jars. Remove the cinnamon. Close with the lids and turn the jars upside down.
Once the jars cool, store in a cool place.