Hi Herb, great question. At 14% ABV it might be a challenge to get fermentation going again even if you do add a bit of sugar.

If you did want to do this you would have to go with a yeast strain that has a high tolerance for alcohol, something like EC1118. What you’d need to do is add some sugar and treat the wine as if it were a stuck fermentation. That means creating a starter using a powerful yeast and rekindling fermentation that way.

I wouldn’t add enough sugar to go all the way to 1.12. That amount of sugar definitely would not get fermented out even by a yeast with a high tolerance for alcohol. Also, a high sugar content and high alcohol content together could be quite prohibitive for yeast.

One option would be to add some sugar, restart fermentation, then periodically add small amounts of sugar. Eventually fermentation will stop due to the alcohol level. Then you can add any additional sugar to sweeten it to your taste. It’s also a good idea to stabilize or filter the wine to prevent the yeast from getting started again later.

Fortified wines, technically, are wines that have additional alcohol added to a finished wine in the form of brandy. If you want to make a port out of this wine, the easy way would be to pick up some brandy and start adding it until it tastes good to you. The additional alcohol will serve to stabilize the wine (this is how fortified wines came about in the beginning as well) as there aren’t many spoilage micro-organisms that can tolerate alcohol over 20% or so.

I hope this helps Herb! Let us know what you decide to do and how it turns out.

Cheers! -Matt