Generation of α‑Diketones and 4‑Hydroxy-2,5-dimethyl-3(2H)‑furanone upon Coffee RoastingImpact of Roast Degree on Reaction Pathways

• Published in: Journal of agricultural and food chemistry 2019-12, Vol.67 (50), p.13829-13839
• Main Authors: Poisson, Luigi, Schaerer, Anja, Spreng, Stefan, Mestdagh, Frédéric, Blank, Imre, Davidek, Tomas
• Format: Article
• Language: English
• Subjects: Coffea - chemistry; Coffee - chemistry; Cooking - instrumentation; Cooking - methods; Furans - chemistry; Hot Temperature; Ketones - chemistry; Molecular Structure; Seeds - chemistry
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/acs.jafc.9b00770

The formation pathways of α-diketones (2,3-butanedione and 2,3-pentanedione) and 4-hydroxy-2,5-dimethyl-3­(2H)-furanone (HDMF) upon coffee roasting were investigated in a kinetic study applying labeled and unlabeled sucrose (CAMOLA approach) in biomimetic in-bean experiments. The results highlighted that not only did the contribution of sucrose to the level of α-diketones in roasted coffee change with the roasting degree but also the portion of the individual reaction pathways. At early roasting stages, 2,3-butanedione was formed from sucrose mainly via the intact sugar skeleton, whereas from the middle of the roasting course, the formation foremost occurred from sugar fragments, primarily by C1/C3 and C2/C2 recombinations. In contrast, 2,3-pentanedione was generated from sucrose mainly via an intact sugar skeleton during the whole roasting cycle; nevertheless, the share of 2,3-pentanedione formed by recombination of fragments (mainly C2/C3) progressively increased with roasting time. HDMF was generated from sucrose almost exclusively via cyclization of an intact skeleton, irrespective of the roast time.