What can excessive oxidation create in beer?

Excessive oxidation in beer can lead to a stale flavor, which is often described as cardboard-like or a significant drop in overall freshness. Oxidation occurs when beer is exposed to air over time, leading to chemical reactions that change the beer's flavor and aroma profile. This process tends to diminish hop character and can enhance certain undesirable flavors, making the beer less enjoyable.

In contrast, fruity aromas are typically associated with hops or yeast character rather than oxidation. A clean finish relates to how the beer feels on the palate and is more about balance and the quality of ingredients or brewing process. Higher carbonation levels can be affected by other factors such as fermentation or carbonation methods, but they are not directly caused by oxidation. Thus, the presence of stale flavors is a definitive outcome of excessive oxidation in beer.