After asking Elmus how the mead production is going, he explains he requires some juniper berries to give it more flavor:
We lost most of the batches we had brewing when... before those things were here. One is just ready to take its turn, though, and it's about time to add some of the flavorings. You can't find them on Solstheim, but if you find yourself back in Skyrim, I wouldn't mind you bringing some juniper berries. They add a different kind of sweetness. Tart. Makes the flavor more round.