How to stop a wine at a SG then backsweeten
 

I am making an apple wine that I want to stop around 1.004 then backsweeten with concentrate. I have added 5 Camden and 2.5 tsp sorbate. Then a day later another 2.5 tsp sorbate. This is a 5 gallon batch. I have not been able to stop the fermentation. What is the proper way to stop fermentation so that I can backsweeten?

Thanks,

Scott

Stopping an active fermentation is like trying to stop a freight train. It probably won't happen, and you might ruin the wine in the process. It's easiest to let it ferment out completely (.990), rack when it's clear to get it off of the spent yeast and then rack onto campden and sorbate once the wine stops throwing any lees at all.

Sorbate doesn't kill yeast, and neither does campden. What sorbate does is inhibit yeast reproduction. Since there are hundreds of billions of yeast in the wine during fermentation, the yeast don't need to reproduce so adding sorbate to it will do nothing.

If you can't wait for it to finish before sweetening, you could try sticking it in the fridge for about a week. Then rack off of the lees. And if it's not totally clear, stick it back in the fridge until it's clear and rack again. THEN you can try sorbate and campden. For me, it's just easier to let it finish and then stabilize when clear and no longer dropping lees.

Sorbate has a rather unpleasant taste, so I wouldn't add any more at this point.

I've never tried to stop a fermentation but instead choose to let it ferment to dryness and then back-sweeten to taste.

I've read that without using chemicals it is possible to chill the wine to just above the freezing point to stop the fermentation then fine filter to remove the yeast.

Agree with everything said in earlier response. Campden and sorbate do nothing to stop an active ferment, that is probably the #1 urban legend of winemaking.
If you are at 1.004 you are likely just days away from hitting dry, and you can then rack and backsweeten.

Some people choose cold crashing, racking, sterile filtering and stabilizing and HOPE that works. Some fortify, some pasteurize. But most allow to ferment dry, stabilize, backsweeten if desired and bulk age or bottle.