Peel the apples and coarsely grate them. The net weight of the apples should be approximately 1 kg. Place the grated apples in a medium pot and sprinkle the sugar on the top. Cover the pot and let sit for one hour. place the pot over medium heat and bring to a boil. Reduce the heat to low and add the lemon juice. Partially cover the pot, and cook for about one hour, stirring occasionally. To check if the jam is ready, remove one tablespoon onto a plate and let cool for a minute. Stop cooking when desired thickness is reached. Transfer into sterilized jars, add one cinnamon stick into each jar, seal and store in a cool place until ready to use. Once a jar is open, store it in the refrigerator.