So I keep a bottle of prune juice in the fridge for my baby. I bought it about 3 months ago. I haven't needed to give her any for a few weeks. Last time I opened the bottle I noticed that it had mysteriously become lightly carbonated. It still tasted OK so I thought nothing of it. Fast forward to this morning and I noticed that the bottle was bulging a lot. I popped the cap and it was like opening a bottle of soda. It still tastes good but now the body is much lighter, it's starting to get sour (in a good way) and it's heavily carbonated. Obviously, there's something working inside of the bottle. What would you do to try to make use of it? It's been in the fridge this entire time. For now I've just attached an airlock so I don't get a prune juice bomb.