A portable GCMS system can identify semi-volatile and volatile compounds in one of the
world’s most consumed beverages in a matter of minutes, as opposed to days.
Compounds in Coffee
» by Sharanya Reddy, LCMS Senior Applications Scientist, PerkinElmer, Waltham, Mass.
Coffee is widely consumed as a beverage because of the stim- ulating effect it produces in humans. The aroma of coffee contributes to the flavor and taste of the beverage and has consequently led to extensive research on its benefits.
Hundreds of volatile/semi- volatile aroma and flavor compounds
have been identified in coffee using traditional laboratory based
headspace GCMS systems. This is a study for rapid fingerprinting of coffee volatile/semi-volatile compounds using solid phase
micro-extraction (SPME) coupled to a portable GCMS system for
separation and detection.
The on-site analysis of coffee using portable technology can be
used for quick quality control check of raw and finished products,
comparison of competitor products, analysis of storage conditions or for process development.
Coffee (1 gm) was placed in headspace vials ( 20 mL vial vol-
ume), capped and placed at room temperature for at least an
hour to allow for saturation of the aroma volatiles in the head-
space. The SPME fiber was directly exposed to the headspace
vapors in the vial for 15 seconds prior to analysis. Below are the
GC and MS conditions:
• Sampling: SPME
• SPME phase: DVB/PDMS, 65 um
• GC injector temp: 270 C
• GC column: MTX- 5, 5 m x 0.1 mm, 0.4 u df
• GC carrier gas: Helium, 0.2 mL/min
• GC column temp: 50- 270 C at 2 C/sec, end hold time for 60 sec
• Transfer line: 250 C
• Injector split ratio: 10 to 1
• Mass analyzer: Toroidal ion trap
• Mass range: 42-500 Da
• Detector: Electron multiplier
Results and discussion
Triplicate analysis of coffee (variety #1) is shown in Figure 1.
The overlay of the total ion current (TIC) suggests the analysis
is very reproducible between injections.
The overlay of TIC of caffeinated and decaffeinated samples
of coffee (variety #1) showed peaks with similar retention time
but in many cases with varying intensities, suggesting similar
compounds are present in the two samples but at different
concentrations (Figure 3). An extra peak was observed in the
caffeinated sample that was not observed in the decaffeinated
The extraneous peak observed in the caffeinated coffee
resembled the spectra of toluene, and comparisons confirmed
its identification. The presence of toluene in the caffeinated
sample is not surprising as literature suggests toluene can be produced in roasted coffee.
Figure 1: Overlay of the TIC of triplicates analysis of headspace
vapors of coffee sample (variety #1).
Figure 2: Overlay of the TIC of triplicates analysis of headspace
vapors of decaffeinated coffee sample (variety #1).