resumo
Arabinose from arabinogalactan side chains was hypothesized as a possible binding site for chlorogenic acids in coffee melanoidins. To investigate this hypothesis, a mixture of 5-O-caffeoylquinic acid (5-CQA), the most abundant chlorogenic acid in green coffee beans, and (alpha 1 -> 5)-L-arabinotriose, structurally related to arabinogalactan side chains, was submitted to dry thermal treatments. The compounds formed during thermal processing were identified by electrospray ionization mass spectrometry (ESI-MS) and characterized by tandem MS (ESI-MSn). Compounds composed by one or two CQAs covalently linked with pentose (Pent) residues (1-12) were identified, along with compounds bearing a sugar moiety but composed exclusively by the quinic or caffeic acid moiety of CQAs. The presence of isomers was demonstrated by liquid chromatography online coupled to ESI-MS and ESI-MSn. Pent(1-2)CQA were identified in coffee samples. These results give evidence for a diversity of chlorogenic acid arabinose hybrids formed during roasting, opening new perspectives for their identification in melanoidin structures. (C) 2015 Elsevier Ltd. All rights reserved.
palavras-chave
SUPERHEATED WATER EXTRACTION; MASS-SPECTROMETRY; BREW MELANOIDINS; CINNAMOYLSHIKIMATE ESTERS; PHENOLIC-COMPOUNDS; MOLECULAR-WEIGHT; LACTONES; POLYSACCHARIDES; MECHANISMS; BEANS
categoria
Chemistry; Food Science & Technology; Nutrition & Dietetics
autores
Moreira, ASP; Coimbra, MA; Nunes, FM; Passos, CP; Santos, SAO; Silvestre, AJD; Silva, AMN; Rangel, M; Domingues, MRM
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Sónia Andreia Oliveira Santos
Investigador Auxiliaragradecimentos
Thanks are due to Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), European Union, QREN, FEDER, and COMPETE for funding the QOPNA research unit (Project PEst-C/QUI/UI0062/2013; FCOMP-01-0124-FEDER-037296), CICECO (Pest-C/CTM/LA0011/2013 and FCOMP-01-0124-FEDER-037271), Projects NORTE-07-0162-FEDER-000048, NORTE-07-0124-FEDER-000066/67 and PEst-C/EQB/LA0006/2011, and RNEM (REDE/1504/REM/2005 that concerns the Portuguese Mass Spectrometry Network). Thanks are also due to FCT for the Grants of Ana Moreira (SFRH/BD/80553/2011) and Claudia Passos (SFRH/BDP/65718/2009).