Fermented Juice? Newbie questions!

[sfshia]

Hi there!
So, I left a quarter-full bottle of Sobe Orange-Carrot juice open on my desk overnight (or maybe two nights. Or a few. I can't recall). Anyway, being in college, I figured it would be fine to drink if I capped it and put it in the fridge.

Well that was about a month ago. I saw it in the fridge and opened it today, wondering if it was still good. I took a small swig of it and was surprised by the taste! It is slightly carbonated and tastes kind of like kombucha. Not sour. Still pretty sweet. Kind of bitter. It has an odd aftertaste. I think it smells yeasty? It doesn't taste "rancid", it tastes and smells more fermented.

My question is, do you think I fermented it? How? Did leaving it out and open collect yeast? And did keeping it capped in the fridge allow the yeast to slow production and feed on the sugar? And if so, would I get sick from it? I don't think I would get deathly ill, as it didn't taste bad. What are your thoughts?

[FermentingYeti]

Drink it! Trust your senses. It sounds like it definitely fermented, as that's pretty much how you create a simple wild ferment. Like you said, if it tastes rancid you probably shouldn't drink it. Fermentation actually makes beverages more healthy. If you're worried, drink a small glass, wait a couple days and try some more if everything goes well. If it were an organic, unpasteurized juice, you would have had yeast from the fruit help out the fermentation. In this case it was probably wild yeasts that started fermenting the sugars.

[MarkR]

Certain yeasts, like yeasts to make lager, actually thrive at refrigerator temperatures. Yeast produces alcohol and carbon dioxide from the sugar in juice. The fizziness is almost certainly carbon dioxide. It sounds like your juice is fermented. If their is no presence of mold or a foul odor, you should be safe to drink it.