Fermentation is the action of yeast consuming sugar and producing alcohol. In dry wine making, the goal of fermentation is for the yeast cells to consume all of the natural sugars in the grape juice, resulting in a dry wine. Sometimes, though, the yeast action can stop prematurely, halting the fermentation process and resulting in a wine that retains undesired sugars. This is referred to as a "stuck fermentation," and when the term is used, it is not a good thing! Fermentations can become stuck for a variety of reasons, from poorly performing yeast strains to excessively warm fermentation temperatures. Sometimes stuck fermentations can be fixed through corrective action on the part of the winemaker. When successful, the wine will ferment to dryness and no harm will be done. If unsuccessful, and the wine retains undesired sugars, the stuck lot may be considered a loss.
