Effect of different aroma extraction methods combined with GC-MS on the aroma profiles of coffee

Abstract

Aroma is arguably the most important factor in the determination of coffee quality. The aroma profiles of coffee could be evaluated by application of gas chromatography-mass spectrometry (GC-MS). Prior to GC-MS analysis, those aroma compounds need to be extracted. This extraction method can be carried out with or without solvent. This research is aimed to know the effect of different aroma extraction methods combined with Gas Chromatography-Mass Spectrometry (GC-MS) on the aroma profiles of medium-roasted coffee (Java Arabica and Java Robusta). The solvent extraction applied Ultrasonic Assisted Extraction (UAE) method with three different solvents (dichlorometane, ethyl acetate, hexane), while Headspace-solid phase microextraction (HS-SPME) was employed as a solvent-free extraction method. The results showed that different solvents used for extraction produce significantly different yield of aroma extracts (α = 0.05). Aroma compounds extracted using solvents combined with GC-MS consisted of 3 groups, i.e. acid, ester, and alcohol, where acid group dominated in all treatments. Meanwhile, HS-SPME GC-MS analysis resulted in an identification of 12 groups, such as aldehyde, pyrazine, pyrrole, pyrimidine, ketones, phenol, esther, acid, furan, alcohol, hydrocarbon, and sulfur compound. Aroma compounds of Java Arabica coffee was dominated by aldehydes, while phenolswas found to be the major compounds identified in Robusta.