Composition of green coffee water-soluble fractions and identification of volatiles formed during roasting

Flavour precursors from water-soluble green coffee low molecular weight (B) and high molecular weight (C) fractions were investigated and the volatiles formed during roasting were identified by high resolution gas chromatography/mass spectrometry (HRGC/MS). Roasting promoted extensive degradation of trigonelline, sucrose and amino acids in fraction (B) and of arabinogalactan in fraction (C). The analyses of the roasted isolated fractions showed that furans are not only formed by sucrose degradation but also by arabinogalactan pyrolysis. Also, pyrazines appear to be mainly formed by pyrolysis of hydroxy amino acids from fraction (C). The results also showed that pyridine found in roasted coffee is not exclusively formed by trigonelline degradation but also by protein pyrolysis.