Cicerone Certified Beer Server Practice Test

How does oxygen exposure affect beer?

1. It enhances the freshness of the beer

2. It can lead to oxidation, resulting in stale, cardboard-like flavors

3. It increases the beer's carbonation

4. It decreases the alcohol content

The correct answer is: It can lead to oxidation, resulting in stale, cardboard-like flavors

Oxygen exposure is a critical factor in beer quality and longevity. When beer is exposed to oxygen, it can undergo oxidation, which significantly impacts its flavor profile. This process leads to the development of undesirable stale flavors, often described as cardboard-like or sherry-like notes. These off-flavors arise because oxygen reacts with various compounds in the beer, altering their chemical structure and resulting in flavors that are not typical of fresh beer. In contrast, the other options do not accurately describe the effects of oxygen on beer. For example, oxygen does not enhance the freshness of beer; rather, it contributes to its deterioration over time. Additionally, while oxygen exposure can affect carbonation levels, it does not inherently increase carbonation. Finally, oxygen exposure does not have an impact on the alcohol content of beer, as the ethanol content remains stable despite oxidation. Therefore, understanding the role of oxygen in beer storage and handling is essential for maintaining the quality of the beer.