With my last batch I turned a gallon into vinegar. Trust me, you will know if it is vinegar. Young cider tastes a little like vinegar but go to the store and buy a bottle of Bragg's cider vinegar and compare. Tastin like vinegar and being vinegar are two different things! If worse comes to worse, keg it and pour some raspberry extract in, carb it, and drink it up. After the first glass you won't be tasing vinegar anymore!