I cooked my grapes overnight in a crock pot. It only has one temperature setting.
The grapes became brown and appeared mushy, and the juice they released was also brown. The taste became almost cherry-like instead of grape, and I didn't taste any burnt flavor. Are they still good?
Yes, they should be perfectly safe. [Assuming you've kept them hot or cold rather than sitting at room temperature, of course.]
Somewhat oxidized (thus, brown) but nothing wrong with that (raisins are brown...unless treated with anti-oxidants.) Also rather like a grape version of apple butter, which is essentially overcooked applesauce, and also brown. Likely better for jam than jelly at this point.
