title: Identification by mass spectrometry of new compounds arising from the reactions involving malvidin-3-glucoside-(O)-catechin, catechin and malvidin-3-glucoside.
abstract: BACKGROUND
  The aim of this work was to study the putative reactions that could occur in red wines between malvidin-3-glucoside-(O)-catechin (mv3glc-(O)-cat) adduct and catechin (cat) or malvidin-3-glucoside (mv3glc) in presence of acetaldehyde.
  
  
  METHODS
  Mv3glc-(O)-cat adduct (1 mM) was incubated with catechin (or mv3glc) in the presence of acetaldehyde (molar ratio of 1:4:10) in 12% ethanol/water at pH 3.2, protected from light and placed in the oven at 30 °C. The formation of the new compounds was monitored by liquid chromatography-diode-array detection/electrospray ionization mass spectrometry (LC-DAD/ESI-MS) analysis in the positive and negative ion mode.
  
  
  RESULTS
  The LC-DAD/ESI-MS characterization allowed the confirmation of the structures of the methylmethine-linked cat-mv3glc-(O)-cat ([M-H](-) m/z 1097) and mv3glc-mv3glc-(O)-cat ([M](+) m/z 1301) adducts.
  
  
  CONCLUSIONS
  The studies performed in model solutions showed that the colorless mv3glc-(O)-cat adduct can undergo some of the characteristic reactions of anthocyanins and flavan-3-ols that occur in red wine in the presence of acetaldehyde forming new methylmethine-bridged compounds.
authors.affiliation: Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Cruz
authors.forename: Nuno
authors.initials: N
authors.lastname: Mateus
authors.forename: Victor
authors.initials: V
authors.lastname: de Freitas
mesh_terms: D000079:Acetaldehyde / Q000032:analysis; D000872:Anthocyanins / Q000737:chemistry*; D002392:Catechin / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D005419:Flavonoids / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry*; D006358:Hot Temperature; D013058:Mass Spectrometry / Q000379:methods*; D014920:Wine / Q000032:analysis
chemical_list: D000872:Anthocyanins; D005419:Flavonoids; D005960:Glucosides; C555518:catechin-(4,8)-malvidin-3-O-glucoside; C458419:malvidin-3-glucoside; D002392:Catechin; D000079:Acetaldehyde