Final answer:
Fortified wine can be sweet or dry depending on when fortification occurs: early fortification results in a sweeter wine, while fortification after complete fermentation leads to a drier wine. Oxidation after opening can adversely affect the wine's taste.
Step-by-step explanation:
If a wine is fortified after the fermentation process, it can be either sweet or dry depending on when the fortification occurs. Generally, the sweetness of a fortified wine depends on the amount of residual sugar present in the wine when the fortification happens. During the standard fermentation process, yeast converts sugars from grapes into ethanol and carbon dioxide under anaerobic conditions. If the winemaker stops the fermentation early by adding a spirit such as brandy, the wine will retain some of its natural sugars, making it sweet. Conversely, if fermentation is allowed to continue until most of the sugars are converted into alcohol, and then the wine is fortified, the resulting wine will be drier.
It is also important to store wine properly after opening to prevent oxidation, which can lead to an unpleasant vinegary taste due to the production of acetic acid. The correct timing of fortification, along with careful handling, can maintain the desired flavor profile of the wine