Chlorogenic acid–arabinose hybrid domains in coffee melanoidins: Evidences from a model system

•Melanoidins are formed during coffee roasting.•Arabinose was hypothesized as a binding site for chlorogenic acids in melanoidins.•Chlorogenic acid–arabinose hybrids were obtained by dry heating of a model mixture.•Two of these hybrid structures were identified in coffee derived samples.•These results open new perspectives for their identification in coffee melanoidins. 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 (α1→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. Pent1–2CQA 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.