Abstract

This study describes a novel odor-active unsaturated aliphatic acid in roasted Brazilian Arabica coffee. (E)-4-Methyl-3-hexenoic acid ((E)-4M3H), which is responsible for a sweaty odor, was identified for the first time using Gas Chromatography-Mass Spectrometry/Olfactometry (GC-MS/O), Aroma Extract Dilution Analysis (AEDA) and Multidimensional Gas Chromatography-Mass Spectrometry (MDGC-MS); its (Z)-isomer was also determined. Additionally, we conducted a model formation experiment to detect the presence of 4M3H in coffee and found that it may be produced nonstereoselectively in the Maillard reactions of L-isoleucine with sugars (xylose, fructose, glucose, rhamnose and sucrose). We also found that 2-methylbutanal derived from L-isoleucine and sugar degradation compounds such as &alpha-dicarbonyl compounds (glyoxal, 2-oxopropanal, 2, 3-butanedione and 2, 3-pentanedione) and α-hydroxy ketones (1-hydroxy-2-propanone and 3-hydroxy-2-butanone) are key factors in the formation of 4M3H. Based on these results, we propose a series of potential nonstereoselective formation pathways for 4M3H.

Keywords:

AEDA, Arabica coffee, formation pathway, MDGC-MS, odorant,

References

Competing interests

The authors have no competing interests.

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Copyright

The authors have no competing interests.