So.....last October I kegged some fresh apple cider (not fermented) for the non drinkers at a BBQ. It was 5 gallons of unpasteurized apple cider (the fresh squeezed stuff that shows up in 1 gallon jugs around fall), a couple sliced up oranges, and a few cinnamon sticks. It was good, and the party killed about half the keg after which it lost itself in the rotating cast of empties in the garage.
Fast forward to now, I'm cleaning a few kegs for a batch of beer and come across a semi full one. I tugged on the pressure release valve and never have I experienced such fury. I bled it down to a less explosive level, hooked up a cobra, and poured a glass. Lots of fluffy white head that died down quickly, juice was a cloudy light brown. Aroma was slightly cidery, strongly citrusy, and with some definately spice.
It would of course have been irresponsible of me not to try at least a sip, so.....mildly tart, orange and cinnamon still there, dry finish masked by a nice aftertaste of apples. Spritzty carbonation but that aside there was a certain watery quality to it, and I was uncertain whether this had actually fermented of it some other nefarious biological process was underway. Took a hydro and it came out at 1.000. In the name of science, I was then obligated to have a few pints....and I was lit like a roman candle!
My best guess is that the natural yeast present on the apple skins or the oranges began working slowly during the chilly fall/winter while the keg sat in the garage. This was definately a spontaneous ferment and I must say that I'm impressed. I've made cider using beer yeast, cider yeast, and wine yeast, and this one has the best flavor of the lot. Less sour, just a pleasant tartness and nice fruit aroma. Judging by OG samples taken previous years when purposely fermenting this fresh squeeze juice, I wager it is in the 6-7% ABV range. Couldn't taste or smell alcohol, but signs point to ...
On the upside, no harsh morning after a la apfelwein, and really no wine character at all. Other than the dubious cloudy appearance, this cider is a real nice drinker and quite a surprise!
Anyone else have experience with accidental fermentation or letting nature take its course?