Many years ago, I used to decorate my trailer with all the empty bottles I drank from. It was my interior decorating scheme at the time. Each year or two I'd have to throw them all in the dumpster and start again because I was totally out of space. Anyway, when I took one chianti bottle off the nail it was hanging from on the ceiling, I realized it had a cup or two of wine left in it. I assure you, this was very unusual indeed. I figured it had to be vinegar by now, but the only way to know for sure was to taste it. To my surprise, it tasted just like sherry, and a pretty good one, at that. Well, I polished off the bottle and chalked it off to a freak accident.
Then last year, some 30 years or so later, I got side-tracked and neglected a half empty gallon of white wine I had left from a 3 gallon batch. Once again, figuring I had screwed up and made vinegar, I tasted it to confirm my theory. And once again, I had a pretty decent sherry on my hands.
This year, I made some apple cider, and then took some of it and "morphed" it into a white wine with some white grape juice and refermented it. It wasn't so great, so I kinda ignored it and just took a drink from it every month or so, hoping I could intentionally duplicate what had happened twice before by accident. After awhile, it developed fusel alcohol taste, which bummed me out. I figured I should have drank it while it was fresh, even if it wasn't so great. So I just let it sit there a few more months to see what it would evolve into next. Tried it again this week, and bingo! It's turning into sherry.
I guess the point of the story is that you may be surprised by the twists and turns of fermenting beverages. I can't say exactly when to or not to give up on a project, but I'm beginning to believe that a wine left in a glass gallon jug half full of wine and half full of air space has a very good chance of "turning" to sherry, if you're the least bit lucky.
Fermentation is like the eighth wonder of the world to me.
