(+)-Catechin-aldehyde condensations: competition between acetaldehyde and glyoxylic acid.
(+)-Catechin reaction with two aldehydes (acetaldehyde and glyoxylic acid) was studied in winelike model solution. The two aldehydes were reacted either individually or together with (+)-catechin and in molar excess. The reactions were followed by HLPC-UV and HPLC-ESI/MS to monitor (+)-catechin disappearance as well as dimer and polymer appearance. In all reactions a reaction order of close to 1 for (+)-catechin disappearance was observed. (+)-Catechin disappearance was slower in the presence of acetaldehyde (t(1/2) = 6.7 +/- 0.2 h) compared to glyoxylic acid (t(1/2) = 2.3 +/- 0.2 h). When the two aldehydes were reacted together, (+)-catechin disappearance was faster (t(1/2) = 2.2 +/- 0.5 h). When aldehydes were reacted separately, the dimer appearance was independent of the type of aldehyde used but the ethyl-bridged dimer disappearance was slower with acetaldehyde. When aldehydes were reacted together, the dimer appearance changed. Ethyl-bridged dimers appeared before carboxymethine-bridged dimers, and their disappearance occurred earlier. Copolymers containing both ethyl and carboxymethine bridges were also observed.
Drinkine
Jessica
J
Faculté d'Oenologie de Bordeaux, Université Victor Segalen Bordeaux2 UMR 1219 INRA, Talence, France.
Glories
Yves
Y
Saucier
Cédric
C
D000079:Acetaldehyde / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry*; D002392:Catechin / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D019281:Dimerization; D006038:Glyoxylates / Q000737:chemistry*; D007700:Kinetics; D021241:Spectrometry, Mass, Electrospray Ionization
D000447:Aldehydes; D006038:Glyoxylates; D002392:Catechin; D000079:Acetaldehyde; C031150:glyoxylic acid