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Advanced Cicerone® · Beer Flavor and Evaluation

Vicinal diketones

Syllabus Path

Vicinal diketones include diacetyl and 2,3-pentanedione; diacetyl commonly reads as butter, buttered popcorn, butterscotch, or slick mouthfeel. Identify both sensory descriptor and likely cause, then decide whether the level fits the style.

  1. III. Beer Flavor and Evaluation
  2. C. Specific beer flavor compounds
  3. 6. Vicinal diketones

Exam Focus

  • Explain vicinal diketones as a sensory evaluation topic within Specific beer flavor compounds.
  • Recognize butter, butterscotch, honey-like, and slick impressions associated with diacetyl or related vicinal diketones while accounting for sensitivity.
  • Explain formation and yeast reduction, then judge the observed level against the style before recommending fermentation or sanitation checks.

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.

References

4 available