How to cook
Wash and clean the berries well. In a pot with a wide bottom, put the water and sugar to boil. Once you boil the sugar syrup, pour the blueberries in. Boil the mixture until it thickens, using a wooden spoon for stirring.
Throughout cooking, you should remove the foam forming on top. Check if the blueberry jam is ready in the standard way - put a drop of it on a porcelain plate - if the drop does not run, it's ready.
Add citric acid, stir and remove it from the heat. Pour the blueberry jam in dry and warm jars, close them briefly and sterilize them for 10 minutes after boiling.