Cicerone Certified Beer Server Practice Exam

Green glass blocks what percentage of light?

1. 5%

2. 20%

3. 50%

4. 80%

The correct answer is: 20%

Green glass typically blocks about 20% of light. This is significant when discussing the impact that light exposure can have on beer, particularly regarding the protection against light-induced off-flavors, such as skunking. The degree of light blocking is important for breweries and bottlers to consider when choosing packaging materials. Green glass, while offering some protection, does not provide as robust a defense as brown glass. Brown glass can filter a higher percentage of light, making it a preferable option for storing certain types of beer. When looking at the other percentages in the choices, 5%, 50%, and 80% represent levels of light blocking that either understate or overstate the capability of green glass. This context is essential in understanding how packaging affects the integrity of beer quality.