Last year I harvested some wild elderberries to process (cook, strain…) for a little juice, something I hadn’t ever done before. I wound up using the juice for a batch of ice cream that I enjoyed and that was really different from other fruit ice creams I’ve made. If I’m describing things accurately, the taste was bitter, but I enjoyed it, and it reminded me of the bitterness of chocolate. I know bitterness is frequently considered an undesirable flavor, but does anyone else enjoy fruits with bitter flavors? Is it even accurate to describe the flavor of elderberries as bitter? Are there other similar fruits that I’ve been missing out on, especially fruits that might not be particularly good for fresh eating but might lend themselves well to various processed uses?
I didn’t like the flavor of elderberries at all. I would not call it bitter, but to me it was not good!
Black currants are best processed. Magnolia vine berries, the 5 flavor fruit are bitter. I like both of these a lot, so may not be what you’re looking for? Black currants are not bitter, but best processed. Magnolia vine is bitter but in a good way 
Mealy and inedible fresh. I use them to make tea, and I love it. I can dry berries and make tea anytime. Some I have I dried 2 years ago and they still are fantastic.
I always think of wild blackberries as having some bitterness. I don’t enjoy them fresh but I always add some to blueberry cakes or cobblers. To me that little bit of bitterness makes the flavor more complicated and tasty.
I don’t enjoy the bitterness of fresh wild blackberries at all either, although it’s mostly tolerable for fresh eating, but I’m glad you mentioned them, because I hadn’t thought of them when I asked my question. Now that you gave me the idea I look forward to seeing if I can make an asset of wild blackberries’ bitterness.