Cicerone Certified Beer Server Practice Exam

Oxygen is known to harm a beer's flavor and aroma primarily through a process called oxidation. When beer is exposed to oxygen, it can lead to undesirable flavors and aromas, such as cardboard or sherry-like notes, which can significantly detract from the intended profile of the beer. This degradation is especially pronounced in hop-forward beers, where even small amounts of oxygen exposure can cause the fresh hop character to fade quickly, replacing it with stale or off-flavors.

Carbon dioxide is part of the normal carbonation process in beer and contributes positively to mouthfeel and overall experience. Nitrogen is used in certain styles, like stouts, to create a smoother texture, while hydrogen is not typically relevant in beer flavor and aroma profiles. Therefore, oxygen's role in negatively affecting beer makes it the primary concern when it comes to maintaining the integrity of beer's flavors and aromas.