Characterisation of the aroma of green Mexican coffee and identification of mouldy/earthy defect

Abstract

The aromas of a reference green Mexican coffee (Arabica) and of a coffee from the same origin, but having a pronounced earthy/mouldy off-taint, were characterised. From comparison of the two aroma profiles, the compounds causing the defect were detected by gas chromatography olfactometry, isolated and concentrated by preparative bi-dimensional gas chromatography, and characterised by gas chromatography-mass spectrometry. Six compounds participated in the off-flavour. Geosmin, 2-methylisoborneol, 2,4,6-trichloroanisole were found to be the main culprits, while three methoxy pyrazines (2-methoxy-3-isopropyl/-3-sec-butyl/-3-isobutyl pyrazine) contributed to a lesser extent to the earthy/ green undertone. The occurrence of the off-flavour could tentatively be linked to post-harvest drying.

Volatile compounds profiles in unroasted Coffea arabica and Coffea canephora beans from different countries

“…(2001), Yeretzian et al (2002), by Toci & Farah (2008) in black-immature coffee beans and by Bertrand et al (2012) in green Arabica coffee beans. 2-propionylpyrrole (1H-Pyrrole) was found in roasted coffee (Toci & Farah, 2008), in green Mexican coffee (Cantergiani et al, 2001) and in black coffee beans (Agresti et al, 2008). Dimethyl trisulfide marked in our study by the e-nose was also shown in the study by Blank (2002) in roasted and ground coffee and in roasted coffee by Michishita et al (2010).…”

“…Beznene acetaldehyde (Phenylacetaldehyde) was also marked in green coffee beans in the study by Cantergiani et al (2001), Yeretzian et al (2002) and in green coffee beans (Coffea arabica) from Hawaii (Lee & Shibamoto, 2002). Also Fisk et al (2012) found these compounds in their study of roasted and ground coffee and Mestdagh et al (2014) in coffee beverage.…”

“…(2001); methyl hexanoate (Hexanoic acid) (Table 2, 3 and 4) was marked in green coffee by Cantergiani at al. (2001), Yeretzian et al (2002), by Toci & Farah (2008) in black-immature coffee beans and by Bertrand et al (2012) in green Arabica coffee beans.…”

“…Methional was found by Semmelroch & Grosch (1995) in roasted coffee powders and brews (Arabica and Robusta) and by Buffo & Cardelli-Freire (2004) Cis-3-Hexenol was identified in coffee in the study by Dchiai et al (2014), Bertrand et al (2012) identified toluene in green Arabica coffee and Nebesny et al (2007) in green coffee beans, Procida et al (1997) in green coffee (arabica and robusta) and Cantergiani at al. (2001) in green C. arabica from Mexico (Flament & Bessière-Thomas, 2002).…”

Identification of volatile compounds and selection of discriminant markers for elephant dung coffee using static headspace gas chromatography–mass spectrometry and chemometrics

“…Gas chromatographymass spectrometry (GCMS) is a powerful analytical technique that is widely used to profile volatile compounds in coffee because it can efficiently separate and identify compounds [11,12,[18][19][20][21]. Coffee samples can be prepared by a solvent extraction method followed by direct liquid injection into the GC column, allowing the detection of volatile and semi-volatile compounds in coffee [12,17,22,23]. However, some volatile compounds may be lost during the sample preparation step.…”