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New approaches to monitor semi-volatile organic compounds released during coffee roasting using flow-through/active sampling and comprehensive two-dimensional gas chromatography

Novaes, Fábio Junior Moreira, Silva Junior, Ademário Iris da, Kulsing, Chadin, Nolvachai, Yada, Bizzo, Humberto Ribeiro, Aquino Neto, Francisco Radler de, Rezende, Claudia Moraes, Marriott, Philip John
Food research international 2019 v.119 pp. 349-358
charcoal, cluster analysis, coconuts, coffee beans, comprehensive two-dimensional gas chromatography, gas chromatography, ionization, molecular weight, roasting, sorbents, volatile organic compounds
A novel dynamic approach is described to profile volatile organic compound (VOC) and semi-VOC (SVOC) emission during coffee roasting aimed at analysing components present in the roasting plume, and to monitor their evolution during the process. Two sorbents – coconut shell charcoal (CSC) and styrene-divinylbenzene resin (XAD-2) – were evaluated while collecting substances in four sequential time intervals (0–3, 3–6, 6–9 and 9–12 min). Extracted VOCs (<200 Da) and SVOCs were analysed by gas chromatography (GC), and comprehensive two-dimensional gas chromatography (GC × GC) with flame ionisation (FID) and time-of-flight mass spectrometry (TOFMS) detection. Results showed CSC extraction presented poor recovery of VOCs and SVOCs released during roasting. However, XAD-2 was able to collect both groups, including SVOCs of >400 Da. GC × GC resolved many co-eluting compounds observed in 1D GC and allowed chemical group type cluster analysis, revealing that many non-polar VOCs are observed within the 0–3 min interval, and that the release of polar and higher molar mass SVOCs were mostly found within the 3–6 min interval. These group-type cluster analyses offer a broad spectrum chemical profile of the released substances. It may also reveal detailed insights into the roast process evolution over time.