What is the role of flor yeast in the aging of Sherry?

The role of flor yeast in the aging of Sherry is primarily to protect the wine from oxidation. Flor yeast is a specific strain of yeast that forms a film on the surface of the wine during the biological aging process in the barrel. This protective layer acts as a barrier between the wine and the air, significantly limiting the exposure to oxygen.

Due to this protective effect, the flor yeast helps maintain the freshness and enhances the development of unique flavors characteristic of biologically aged Sherry, such as Manzanilla or Fino. The presence of flor allows for a special aging process that imparts certain aromatic compounds while preventing the oxidative qualities that can occur without the yeast. As a result, the wine retains its vibrancy and becomes known for its distinctive briny and nutty notes.

Other options might suggest roles that are not associated with flor yeast. For instance, while sweetness, carbonation, and flavor complexity are important features of wine, they do not relate directly to the primary function of flor yeast in the aging process of Sherry. Therefore, the correct understanding of flor yeast's critical role is fundamentally tied to its protective capability against oxidation, helping to shape the unique profile of Sherry wines.