Cicerone Certified Beer Server Practice Test

Exposure to oxygen can cause beer to have a stale or cardboard-like taste, as well as a loss of aroma. Carbon dioxide and nitrogen are commonly used for carbonation and packaging, while oxygen should be kept at low levels during the brewing process. Option D does not provide any relevant information and is not a possible choice. While carbon dioxide can have negative effects if over carbonated, it does not harm the flavor and aroma of beer like oxygen does. Nitrogen also does not have a significant impact on the flavor and aroma of beer. Therefore, option C, oxygen, is the only gas that can negatively affect the flavor and aroma of beer.