Squeeze all the oranges, mix the juice with the cinnamon and citric acid. Add a dash of grenadine so that the jam gets a nicer color and becomes a little sweeter. Mix everything again and let it steep for about 1 hour.
Then heat with the preserving sugar in a large saucepan while stirring until it is bubbly. Then let it cook for about 4 minutes. To do this, follow the instructions on the preserving sugar packaging!
Pour the jam into cleaned jars, close the lids tightly and immediately turn upside down for 10 minutes. Let it cool down, done!