Cicerone Certified Beer Server Practice Exam

If draft lines are not cleaned regularly, which of the following flavors is most likely to develop?

1. Banana

2. Butter

3. Paper

4. Skunk

The correct answer is: Butter

When draft lines are not cleaned regularly, the most likely flavor to develop is butter. This off-flavor is often the result of a compound called diacetyl, which can be produced by certain strains of yeast during fermentation, but more commonly arises from bacteria such as Lactobacillus or Pediococcus that can thrive in unclean lines. These bacteria are notably faster in reproduction and can lead to the production of diacetyl, which imparts a distinct buttery taste to the beer. Maintaining clean draft lines is crucial to preventing this flavor development, as residues from previous servings, including beer remnants and microbial growth, can contribute to the formation of unwanted flavors. Proper cleaning schedules help eliminate residues and the environments that promote bacterial growth, ensuring that the beer maintains its intended flavor profile.