Thoroughly sort the lilacberries, remove the stems, wash and drain. It is important to ensure that only the ripe, shiny black berries are used, because unripe berries, the umbellate stalks and the seeds contain sambunigrin, which can cause nausea and diarrhea.
Strain the lilac berries through a sieve or using a mill. Bring the resulting juice with sugar and cinnamon to the boil and simmer for about 5 minutes, stirring, until the sugar has dissolved.
Pour the still hot liquid into clean, hot rinsed bottles. Close the bottles tightly. Store opened bottles in the refrigerator and use as soon as possible.
The juice can be drunk pure or mixed with fruit tea. It tastes very sweet on its own. You can also use the juice as a base for lilacberry liqueur.