How can excessive oxygen exposure affect wine quality?

Excessive oxygen exposure during the winemaking process can significantly compromise wine quality, primarily by causing oxidation, which alters the wine's flavor, aroma, and overall integrity. When wine is exposed to too much oxygen, it can lead to unwanted chemical reactions that produce off-flavors and aromas, often described as being "sherry-like" or "flat." This oxidation can degrade the wine's fresh fruit characteristics, diminish its vibrancy, and ultimately cause spoilage.

Moreover, oxidative conditions foster the growth of unwanted microorganisms, which can spoil the wine and lead to undesirable traits. In contrast, controlled oxygen exposure can be beneficial, such as in the aging process for certain wines, where it can help develop complex flavors. However, excessive or uncontrolled exposure is clearly detrimental, reinforcing the importance of managing oxygen levels carefully throughout the winemaking process.