Lipid characterization of arabica and robusta coffee beans by liquid chromatography-ion mobility-mass spectrometry

Abstract

Coffee lipids, such as kahweol, free fatty acids, and triacylglycerols have been described as discriminant markers for arabica and robusta coffees. The lipid characterization of these species may help better understand their differences. Due to the complexity of the lipids, a high-resolution technique, such as liquid chromatography coupled to ion mobility quadrupole time-of-flight mass spectrometry (LC-IM-qTOF-MS), is crucial for a comprehensive perspective of the coffee lipids. Therefore, we analyzed green arabica and robusta coffee beans using LC-IM-qTOF-MS to characterize the lipidome. Brazilian green coffee beans were extracted using the Matyash method. After the LC-IM-qTOF-MS analysis, the raw data were processed via a lipidomics workflow in MS-DIAL. Differences between the lipid composition of the coffee species were revealed by PCA, PLS-DA, and cluster analysis. Around 180 lipid species from 15 distinct classes were annotated in the positive and negative electrospray ionization modes, including different isobaric βN-alkanoyl-5-hydroxytryptamides (C5-HT). Triacylglycerols (TG) (TG 48:2, TG 58:5) and C5-HTs (C22(OH)–5HT, C24–5HT) were positively associated with arabica coffees, whereas diacylglycerols (DG) (DG 36:0, 38:3) were linked to robusta. This investigation expands our knowledge about coffee lipids, opening new possibilities to improve authentication and agronomical practices.