Evaluation of the Effect of Roasting on the Structure of Coffee Galactomannans Using Model Oligosaccharides
- 6 August 2011
- journal article
- Published by American Chemical Society (ACS) in Journal of Agricultural and Food Chemistry
- Vol. 59 (18), 10078-10087
- https://doi.org/10.1021/jf2021072
Abstract
The roasting process induces structural changes in coffee galactomannans. To know more about the reaction pathways that occur during the roasting of coffee, mannosyl and galactomannosyl oligosaccharides, having a degree of polymerization (DP) between 3 and 4, were used as models for galactomannans. These compounds were dry-heated under air atmosphere from room temperature to 200 °C, being maintained at 200 °C for different periods of time. The roasted materials were analyzed by mass spectrometry (ESI-MS, MALDI-MS, and ESI-MSn) and methylation analysis. In the MS spectra were identified several [M + Na]+ ions belonging to a series from a single hexose to 10 hexose residues ([Hex1–10 + Na]+). The ions corresponding to their respective mono- and tridehydrated derivatives ([Hex2–10 – H2O + Na]+ and [Hex2–10 – 3H2O + Na]+, respectively) were also identified. ESI-MSn as well as deuterium-labeling and alditol derivatization experiments showed that the tridehydrations occur at the reducing end of the oligosaccharides. The identification of (1→2)- and (1→6)-linked mannose residues and (1→4)-linked glucose residues by methylation analysis allowed the conclusion that transglycosylation and isomerization reactions occur during dry thermal processing.This publication has 31 references indexed in Scilit:
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