Determination of the Alkylpyrazine Composition of Coffee Using Stable Isotope Dilution–Gas Chromatography–Mass Spectrometry (SIDA-GC-MS)

• Published in: Journal of agricultural and food chemistry Vol. 61; no. 26; pp. 6274 - 6281
• Main Authors: Pickard, Stephanie, Becker, Irina, Merz, Karl-Heinz, Richling, Elke
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 03.07.2013; Amer Chemical Soc
• Subjects: Agriculture; Agriculture, Multidisciplinary; Alkylation; Biological and medical sciences; Caffeine - analysis; Chemistry; Chemistry, Applied; Coffee - chemistry; decaffeination; flavor; Food Handling; Food industries; Food Science & Technology; Fundamental and applied biological sciences. Psychology; gas chromatography; Humans; isotope dilution technique; Life Sciences & Biomedicine; liquid-liquid extraction; Maillard Reaction; mass spectrometry; Physical Sciences; Pyrazines - analysis; Pyrazines - chemistry; quantitative analysis; Science & Technology; stable isotopes; Taste; GC-MS; decaffeinated coffee; alkylpyrazines; SIDA; extraction solvent; coffee; ANTIOXIDANT ACTIVITY; ARABICA COFFEE; APOPTOSIS; POTENT ODORANTS; ROASTED COFFEE; GENTAMICIN; SUGAR; AROMA FORMATION; TETRAMETHYLPYRAZINE; CHARACTER IMPACT ODORANTS; Gas chromatography; Isotope dilution; Solvent extraction; Decaffeinated coffee; Mass spectrometry
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf401223w

A stable isotope dilution analysis based on gas chromatography–mass spectrometry analysis (SIDA-GC-MS) was developed for the quantitative analysis of 12 alkylpyrazines found in commercially available coffee samples. These compounds contribute to coffee flavor. The accuracy of this method was tested by analyzing model mixtures of alkylpyrazines. Comparisons of alkylpyrazine-concentrations suggested that water as extraction solvent was superior to dichloromethane. The distribution patterns of alkylpyrazines in different roasted coffees were quite similar. The most abundant alkylpyrazine in each coffee sample was 2-methylpyrazine, followed by 2,6-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-5-methylpyrazine, and 2,3,5-trimethylpyrazine, respectively. Among the alkylpyrazines tested, 2,3-dimethylpyrazine, 2-ethyl-3-methylpyrazine, 2-ethyl-3,6-dimethylpyrazine, and 2-ethyl-3,5-dimethylpyrazine revealed the lowest concentrations in roasted coffee. By the use of isotope dilution analysis, the total concentrations of alkylpyrazines in commercially available ground coffee ranged between 82.1 and 211.6 mg/kg, respectively. Decaffeinated coffee samples were found to contain lower amounts of alkylpyrazines than regular coffee samples by a factor of 0.3–0.7, which might be a result of the decaffeination procedure.