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QUANTITATIVE ANALYSIS OF DIACETYL, PENTANEDIONE AND THEIR PRECURSORS DURING BEER FERMENTATION BY AN ACCURATE GC/MS METHOD
Author(s) -
Landaud Sophie,
Lieben Pascale,
Picque Daniel
Publication year - 1998
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1998.tb00981.x
Subject(s) - chemistry , diacetyl , derivatization , detection limit , vicinal , chromatography , toluene , derivative (finance) , gas chromatography , diketone , mass spectrometry , organic chemistry , financial economics , economics
A GC/MS method previously described for diacetyl was developed for the quantification of 2,3‐pentanedione, and the derivatization procedure was modified for the determination of α‐acetohydroxy acid. The reaction of 2,3‐pentanedione with 4,5‐dichloro‐1,2‐diaminobenzene produced 6,7‐dichloro‐2‐methyl‐3‐ethylquinoxaline (DCMEQ), which was extracted with toluene and determined by gas chromatography using a mass selective detector. The formation of DCMEQ was linearly correlated with the 2,3‐pentanedione concentration. The method was very simple and sensitive. The detection limit of the 2,3‐pentanedione derivative and diacetyl derivative was 0.0007 mg/litre and 0.0002 mg/litre of the toluene extract respectively, and the determination limit was 0.001 mg/litre and 0.0007 mg/litre, respectively. Cautious sample treatment led to a low (10%) and controlled conversion of α‐acetohydroxy acids to vicinal diketones. This reproducible percentage of conversion made it possible to determine precisely free vicinal diketones and α‐acetohydroxy acids . The method was applied to the determination of precursors and vicinal diketones concentrations during beer fermentation .