Exam Focus
- Explain vicinal diketones as a sensory evaluation topic within Specific beer flavor compounds.
- Use specific evidence such as appearance, aroma, taste, mouthfeel, finish, intensity, likely compound, and production or handling context.
- Apply the topic to accurate flavor description, source attribution, and style-fit judgment rather than repeating the heading alone.
Core knowledge
- Vicinal diketones include diacetyl and 2,3-pentanedione; diacetyl commonly reads as butter, buttered popcorn, butterscotch, or slick mouthfeel.
- Sources include normal yeast metabolism, premature cooling or separation from yeast, insufficient maturation, Pediococcus or other microbes, and draft-line infection.
- Low diacetyl may be acceptable in some British and Czech styles, but it is a fault in many clean lagers and hop-forward beers.
Study application
Identify both sensory descriptor and likely cause, then decide whether the level fits the style.
Key Terms
- Low diacetyl
- Low diacetyl may be acceptable in some British and Czech styles, but it is a fault in many clean lagers and hop-forward beers.