Metabolomics Fingerprint of Philippine Coffee by SPME-GCMS for Geographical and Varietal Classification

Headspace metabolites of Philippine Arabica and Robusta coffees grown from different geographical origins were identified using solid-phase microextraction gas chromatography mass spectrometry (SPME-GCMS). A great number of metabolites with a wide variety of functional groups were extracted from two different coffee varieties. About forty prominent metabolites were identified in reference to the NIST spectral database (MS library) and twenty seven of which were confirmed using reference standards. The metabolomics fingerprint of Arabica coffee considerably differs with Robusta coffee and geographical origin slightly alters the fingerprint profile of coffee samples. Chemometric analysis such as principal component analysis (PCA) displays a good classification between Arabica and Robusta coffee samples. Although, Arabica coffee samples from different geographical origins were clustered separately from each other, the proximity of clusters between Arabica coffee samples which can be classified into one large group, indicated their close similarity of headspace metabolites. PCA also identified several key metabolites for the distinction of this group from Robusta coffees which is attributed to the higher amount of maltol, acetic acid, 2-furancarboxaldehyde, 1-H-pyrrole-2-carboxaldehyde and lower concentration of phenol and 4-ethyl-2-methoxyphenol in all Arabica samples. These discriminating compounds could be useful quality markers to differentiate Arabica with Robusta coffee. Results revealed that the headspace metabolites in coffee provides significant information on its inherent aroma quality. Also, the findings suggested that the overall quality of Philippine coffee is variety and region specific.