All the information I've found about flavoring with grape uses either grapes or commercial grape juice. I have a lot of grape juice I've canned, no sugar added just grapes cooked a little to help release the juice and then run through a mill and canned. It has a small amount of pulp left in the bottom of the jars. I have tried to add it as flavoring and it's a little too tart. I'm wondering if I should add some sugar? Has anyone here used juice like this to flavor? I put mine up like I do with the idea that there is no added sugar so I can use it in different ways. I feel like it must be a lot more concentrated than commercial juice. Any thoughts?