How to make
Choose large and healthy blackberries. Wash them thoroughly and allow to dry. To get a nice jam and for the blackberry fruits to remain intact, first prepare a very thick sugar syrup from the water and sugar. Allow it to cool and drop the cleaned blackberries in it. Let them stay as is for 30 minutes, then move the dish to a hot stove.
During boiling, the foam needs to be removed. Stir carefully from time to time to keep the fruits whole. Leave the blackberry jam to boil until thickened - to the point where drops of it no longer run across the plate. Add the citric acid and boil the jam for 2-3 minutes.
Remove it from the heat, remove the foam once again and transfer it into another container. Allow to stand for one night, then put it in jars and close them.