Cicerone Certified Beer Server Practice Exam

The correct answer is that brown glass blocks approximately 98% of light, which is crucial for protecting beers, especially those that are light-sensitive. Light exposure can cause photo-oxidation, leading to off-flavors and spoilage, particularly in pale lagers and other vulnerable styles.

The use of brown glass minimizes the risk of light-strike, which occurs when certain wavelengths of light react with the compounds in the beer, resulting in undesirable flavors often described as skunky. Consequently, brown glass is a preferred choice for packaging certain types of beer to help maintain flavor integrity and quality over time.

Less effective options, such as clear or green glass, allow more light to penetrate, which can negatively impact the beer, while brown glass provides the best defense against these negative effects.