🍷 Stuck fermentation
When the yeast stops working too early and sugar is left behind.
Stuck fermentation is when yeast stops working too early and extra sugar is left in the wine. Normally fermentation continues until the yeast has turned all the sugar into alcohol and carbon dioxide. But sometimes the process stalls and the wine stays sweet or only partly fermented.
The causes vary. Yeast may be chilled if the cellar is too cold, or overheated in hot weather. It may lack nutrients. Fermentation may be stopped by too much sugar in the must, or by alcohol so high that the yeast dies. Residues of vineyard treatments can matter too.
It is a serious problem. A wine that has not finished fermenting may start to spoil. The winemaker tries to restart it by warming the wine, adding nutrients or fresh yeast. Stuck fermentation is linked to alcoholic fermentation in general and to the condition of the yeast. Sometimes fermentation is stopped on purpose to keep sweetness, as in fortified wines.
Links
- Protects from
- 🍷 Yeast
- Part of
- 🍷 Alcoholic fermentation
Frequently asked questions
What is a stuck fermentation?
When yeast stops working too early and leaves extra sugar in the wine.
Why can fermentation stop?
Cold or overheating, lack of nutrients, too much sugar, or high alcohol.
How does a winemaker restart fermentation?
By warming the wine and adding yeast nutrients or fresh yeast.
Similar
🍷 Fermentation temperature · 🍷 Pomace cap · 🍷 Must · 🍷 Alcoholic fermentation