RATIONALE 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. Copyright © 2012 John Wiley & Sons, Ltd.