Accidentally Made Wine.

Sort of…  A few weeks ago I collected about 80 pounds of grapes from our vines.  Once cleaned, I had 46 pounds of actual grapes, which I boiled down to juice.  I made a lot of jelly with the resulting four gallons of juice, but had nearly a gallon left so I put it in the refrigerator thinking I’d make more.  It was in a sealed plastic bottle and yesterday I noticed that the bottle was bulging so I opened it and heard a nice hiss and then tiny bubbles floated to the top.  It has started to ferment.  Out of curiosity, I had a sip.  It actually tastes pretty good; like carbonated grape juiced.

I know there’s at least one professional brewer here and likely several DIY types.  I feel like this stuff is probably safe to drink since I boiled it before I put it in the refrigerator, but I have no idea what yeast is living in it.  I’d like to kill the bugs and stop the fermentation process, but keep the fizz so I could guzzle it.  Any suggestions?

Eureka!  Home made Lambrusco.

Old grapes? Cant be any worse than prison hootch....

Camden tablets (potassium or sodium metabisulfite) will stop the fermentation.  But, to be honest, by the time you get some, the yeast will most likely have converted most of  the sugars to alcohol.

as for safe to drink?    Absolutely.   Wine is never boiled beforehand, so that might be a flavor change.    The alcohol performs the sterilization.

Edit:  a few weeks ago?    I'd say fermentation is complete.

I wish I were in your shoes.  Thanks to the animals that live in my neighborhood, I got nothing.

Bummer.

One thing that I've saw when I was making wine a long time ago- if you bottle it too early, it will retain the carbonation.  Somewhat like beer does.

It's really interesting that you got wild yeast to work 1) after being boiled, and 2) in the fridge.  I think that's pretty cool- tough little buggers.

Do you have any firm, glass bottles around?  That will help maintain what you have.  One thing to note- since you got wild yeast to survive that, they will be tough to really kill off- so it's pretty likely that the juice will spoil pretty quickly.  In other words, keep what you can drink within a week or so (like most other fruit in your 'fridge), and take the rest to actually finish making wine with.  

Sounds like its time for a still. Bit of Grappa to get you through the winter.

NOHOME said:

Sounds like its time for a still. Bit of Grappa to get you through the winter.

Technically, if you just distill the juice, you get brandy.

Grappa is when they steam distilled the skins after pressing.

But that's ok, I'd like to do the same- or take the remaining skins, add 5lb of sugar, enough water, let ferment and then distill.  That would be nice.

It's a miracle 

Yeah... when making actual wine, they don't bother boiling it at all.

I don't know enough about the details of fermenting grapes, but there really shouldn't be anything in there that would make you sick. That's why people fermented stuff. Grape juice also tends not to take with things that make people sick because grape juice is quite acidic.

What surprises me is that it started to ferment after being boiled. There shouldn't have been any yeast living in the juice. Would have had to be living in the plastic bottle or something you handled the juice with after it cooled.

May well not be a yeast fermentation. Very likely bacterial, or mix of bacteria and yeast. If you used a spoon (especially a wooden one) that had been used for things like yogurt, you've likely got got some of those cultures. These are perfectly safe to consume. You eat them in yogurt after all. Vintners just try to avoid them because soured or funky wines are generally considered flawed.

You may be on to something there.  Half the juice was from concords and half from a white grape.  I boiled the grapes down and did the first filter into new plastic bins and kept them in the refrigerator.  The next day, I filtered the juice again to remove more of the pulp.  I used a clean cotton shirt for this.  Then I made the jelly, which requires boiling the juice and adding sugar and pectin.  I used a wooden spoon to stir the boiling juice mix, but not the cool juice.  I transfered the left over juices to the same new, clean bucket that had the whole grapes inside.  I rinsed the bucket before the juice went in though.  Later I poured it into a Simply Lemonade bottle we had just emptied.  Then back in the refrigerator.  Clearly lots of opportunity for random bugs to jump in.