Why did my wine stop fermenting?

[arcane10]

Greetings all,

Recently I went to the store and bought 5 gallons worth of white welch's grape juice. I sanitized my equipment, added bentonite, pectic enzyme, yeast nutrient, acid blend, half a pound of sugar and used a Montrachet wine yeast to get it started.

Fermentation took about 12 hours to start, which was weird given that all my other wines fermented within an hour or two. Anyway, fermentation was going quite vigorously for 2 days until this morning when it suddenly stopped. Why did this happen and how did I get it started again? Here are a few reasons as to why I think it stopped:

1) As I was putting everything in to the primary fermenter my friend acidently dropped his pencil in it and reaches into his bucket, without washing his hands, and took it out, so I assume it got contaminated.

2) When it was vigorously fermenting, temperatures went from 72 to 80 degrees, which I assume ruined the fermentation

3) I looked at the Welchs juice that I bought and it had preservatives in it.

Anyway, what do you all suggest I do if I intend to save this wine? If its not possible to save, then I might as well just throw it away since it hasnt been too long and just start from scratch using actual grape juice concentrate.

 

[grapeman]

It sounds like you have no idea of the starting specific gravity. If you only added a half pound of sugar for the whole thing, it may have been really low. That said, it could have fermented dry in two or three days.
1) The pencil and hand would not ruin the wine. In commercial wines a lot worse than that goes into the must- not always, but it can and does.
2The temperature rising is a normal thing during fermentation- the fermentation process creates heat.
3) Try to use juice with no sorbates, but generally it is small amounts and if fermentation began, it was not too much.


Relax, take a hydrometer reading- Oh you probably don't have one- go get one and take a reading to see where it is.

Your wine will likely be fine but may be low alcohol and without an initial reading you have no idea what it is. Hydrometers are only five bucks or so.

 

[Turock]

Montrachet needs a good nutrient protocol because it can get easily stressed. Stressed yeast can't finish a ferment and oftentimes can produce large quantities of H2S. Always step-feed nutrient. If you didn't have a high enough brix to begin with, then when the yeast uses up the sugars present, they will just stop. Not knowing a beginning SG is a problem in diagnosing just what is going on.

You don't need bentonite on Welch's. And you don't want to use it right ontop of pectic enzyme, altho the use of enzyme with concentrate isn't really necessary, altho it doesn't hurt to use it as it might help with clarity. Always time your bentonite additions--use pectic enzyme on fruit and then add the bentonite on the 3rd day of the ferment so you don't inactivate the enzyme.

 

[garymc]

I suggest the old taste test. Smell and taste it. It shouldn't taste real good being so green and full of yeast, but if it tastes pretty close to wine, not very sweet, and doesn't stink, you've probably made some mild wine.