Why are finos and manzanillas fortified to 15% ABV?

Finos and manzanillas are fortified to 15% ABV to create a suitable environment for the development of flor yeast, which is responsible for the unique characteristics of these sherry styles. At this alcohol level, the conditions are optimal for the flor to thrive, leading to a layer of yeast that forms on the surface of the wine. This biological aging process enhances the wine's flavor profile, contributing to its complex aromas and taste, characterized by finesse and a distinctive freshness.

The biological aging process under flor also serves to protect the wine from oxidation, ensuring that it maintains its fresh and delicate characteristics. This is vital for styles like fino and manzanilla, which are appreciated for their light, crisp, and aromatic qualities. Therefore, the fortification level is crucial not only for flavor development but also for preserving the integrity of the wine during its aging process.