Influence of provenance and roast degree on the composition of potent odorants in Arabica coffees

Twenty-eight potent odorants were quantified by stable isotope dilution ass ays of medium-roasted Arabica coffee blends from Colombia (Col), Brazil (Br a), El Salvador (El) and Kenya (Ken) as well as the varieties Tipica (Tip) from Colombia and Caturra from the regions Pinas (Cat-P) and Quevedo (Cat-Q ) in Ecuador. The blends from Col and Bra were similar in their composition of odorants. Ken contained higher amounts of 3-mercapto-3-methylbutylforma te than Col and Bra, while 2-furfurylthiol, guaiacol and bethylguaiacol wer e present in lower concentrations. El contained less 4-vinylguaiacol and 2- furfurylthiol, but more 3-methyl-2-buten-1-thiol. Tip, Cat-P and Cat-Q diff ered from Col, Bra and Ken in having lower amounts of 2,3-butanedione, 2,3- pentanedione and 4-hydroxy-2,5-dimethyl-3(2H)-furanone and higher contents of guaiacol, 3-mercapto-3-methylbutylformate and 3-methyl-2-buten-1-thiol. The largest amount of 2-furfurylthiol was found in Tip and Cat-P. The blend s from Col and Ken and the variety Tip showed a significant increase of gua iacol, 4-ethylguaiacol and 3-methyl-2-buten-1-thiol when the roast degree w as raised. 2-Furfurylthiol and 2(5)-ethyl-4-hydroxy-5(2)-methyl-3(2H)furano ne increased only in Col and Ken, while in Tip the amounts of carbonyl comp ounds, 4-hydroxy-2,5-dimethyl-(2H)furanone, methional and (E)-beta-damascen one decreased during roasting from medium to dark.