Hello! I recently canned a small batch of grape tomatoes in vinegar that called for a brine of 2 cups vinegar: 4 cups water. I had a lot of brine left over, so I poured it into a glass jar and stored it into the fridge. Safe to bring it back up to a boil and use it? If not, I'll use it for a frigerated version of the recipe.

Another question: that recipe also has an apple cider vinegar version. I discovered I have (%5) apple cider in my panty, but it's been opened and has been unused for who-knows-how-long. Still suitable for canning? Or toss it?

Thank you for answering my newbie questions!