Metabolite Profiling of Premium Civet Luwak Bio-Transformed Coffee Compared with Conventional Coffee Types, as Analyzed Using Chemometric Tools

Abstract

Luwak (civet) coffee is one of the most precious and exotic coffee commodities in the world. It has garnered an increasing reputation as the rarest and most expensive coffee, with an annual production. Many targeted analytical techniques have been reported for the discrimination of specialty coffee commodities, such as Luwak coffee, from other ordinary coffee. This study presents the first comparative metabolomics approach for Luwak coffee analysis compared to other coffee products, targeting secondary and aroma metabolites using nuclear magnetic resonance (NMR), gas chromatography (GC), or liquid chromatography (LC) coupled with mass spectrometry (MS). Chemometric modeling of these datasets showed significant classification among all samples and aided in identifying potential novel markers for Luwak coffee from other coffee samples. Markers have indicated that C. arabica was the source of Luwak coffee, with several new markers being identified, including kahweol, chlorogenic acid lactones, and elaidic acid. Aroma profiling using solid-phase micro-extraction (SPME) coupled with GC/MS revealed higher levels of guaiacol derivatives, pyrazines, and furans in roasted Luwak coffee compared with roasted C. arabica. Quantification of the major metabolites was attempted using NMR for Luwak coffee to enable future standardization. Lower levels of alkaloids (caffeine 2.85 µg/mg, trigonelline 0.14 µg/mg, and xanthine 0.03 µg/mg) were detected, compared with C. arabica. Other metabolites that were quantified in civet coffee included kahweol and difurfuryl ether at 1.37 and 0.15 µg/mg, respectively.

Metabolic Profiling, Antioxidant Activity, and Alpha-Glucosidase Inhibitory Activity of the Roasted Beans of Luwak (Civet) Coffee

“…11 This instrument has also been used to identify civet coffee metabolites dissolved in methanol. 12 The findings revealed that civet coffee had higher levels of fatty acids than regular coffee. Easy sample preparation is one of the fundamental advantages of NMR spectroscopy.…”

“…This method has successfully identified and quantified several metabolites in green civet coffee beans without separation, such as alanine, asparagine, GABA, malic acid, chlorogenic acid, quinic acid, choline, sucrose, caffeine, and trigonelline . This instrument has also been used to identify civet coffee metabolites dissolved in methanol . The findings revealed that civet coffee had higher levels of fatty acids than regular coffee.…”