title: Nonenzymatic Transglycosylation Reactions Induced by Roasting: New Insights from Models Mimicking Coffee Bean Regions with Distinct Polysaccharide Composition.
abstract: Three mixtures containing different molar proportions of (β1→4)-D-mannotriose and (α1→5)-L-arabinotriose, oligosaccharides structurally related to coffee polysaccharides (galactomannans and arabinogalactans), were roasted at 200 °C for different periods. Electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS(n)) analyses of labeled ((18)O) and unlabeled samples allowed identification of not only nonhybrid oligosaccharides but also hybrid oligosaccharides composed of both hexose and pentose units. The identification of hybrid oligosaccharides allowed us to infer the occurrence of nonenzymatic transglycosylation reactions involving both oligosaccharides in the starting mixtures. Also, it was observed that using different proportions of the oligosaccharides in the starting mixtures and extents of thermal treatment led to a variation in the composition of the compounds formed. These results have led to the conclusion that, depending on the distribution of the polysaccharides in the bean cell walls and the roasting conditions, different nonhybrid and hybrid structures can be formed during coffee roasting.
authors: QOPNA, Department of Chemistry, University of Aveiro , 3810-193 Aveiro, Portugal.
authors: Ana S P
authors: AS
authors: Moreira
authors: QOPNA, Department of Chemistry, University of Aveiro , 3810-193 Aveiro, Portugal.
authors: Joana
authors: J
authors: Simões
authors: CQ-VR, Chemistry Research Centre, Department of Chemistry, University of Trás-os-Montes e Alto Douro , 5001-801 Vila Real, Portugal.
authors: Fernando M
authors: FM
authors: Nunes
authors: CICECO, Department of Chemistry, University of Aveiro , 3810-193 Aveiro, Portugal.
authors: Dmitry V
authors: DV
authors: Evtuguin
authors: QOPNA, Department of Chemistry, University of Aveiro , 3810-193 Aveiro, Portugal.
authors: Pedro
authors: P
authors: Domingues
authors: QOPNA, Department of Chemistry, University of Aveiro , 3810-193 Aveiro, Portugal.
authors: Manuel A
authors: MA
authors: Coimbra
authors: QOPNA, Department of Chemistry, University of Aveiro , 3810-193 Aveiro, Portugal.
authors: M Rosário M
authors: MR
authors: Domingues
mesh_terms: D040503:Coffea / Q000737:chemistry*; D003296:Cooking; D006031:Glycosylation; D006358:Hot Temperature; D013058:Mass Spectrometry; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry*
chemical_list: D010936:Plant Extracts; D011134:Polysaccharides
keywords: arabinogalactans; coffee; galactomannans; isobars; isomers; thermal processing; transglycosylation