Vicinal Diketones in Beer
Dist Line: Determination of vicinal diketones (VDK) in beer
Diacetyl (2,3-butanedione) and 2,3-pentanedione are vicinal diketones (VDK) which are formed during beer fermentation. VDK can have a significant effect on beer flavor, presence above their flavour threshold (approx. 0.1 mg/L for diacetyl and 1.0 mg/L for 2,3-pentanedione) can lead to butter/butterscotch like flavors that are undesired in most beer styles. The concentration of VDK depends on numerous process conditions, such as wort compostion, fermentation regime, yeast strain, but can also be caused by microbial contamination. The control of VDK levels during fermentation is an important aspect of quality control in a brewery. VDK can be determined by a variety of analytical methods. The usage of colorimetric assays, e.g., through complex formation with o-phenylenediamine and gas chromatography (GC) are most commom and recommended by the European Brewery Convention (EBC).