How is Fino Sherry's exposure to oxygen managed during aging?

Fino Sherry is uniquely characterized by its aging process, which involves careful management of oxygen exposure. This is primarily achieved through the formation of flor yeast, a natural phenomenon where a layer of yeast forms on the surface of the wine. The flor yeast acts as a protective barrier, limiting the amount of oxygen that can come into contact with the wine beneath it. This controlled exposure to oxygen is crucial as it allows Fino Sherry to develop its signature delicate flavors and aromas while preventing oxidation that would alter its profile in undesirable ways.

In contrast, the other options do not accurately describe the aging process of Fino Sherry. Airtight containers would not allow the necessary yeast growth, adding preservatives is not a common practice in the traditional Sherry aging process, and aging in sealed bottles does not occur for Fino, as this style is typically aged in casks where oxygen can still play a role, albeit limited by the flor. Thus, the role of flor yeast is central to maintaining the intended characteristics of Fino Sherry during its aging process.