A kinetic study of the reactions of (+)‐catechin with aldehydes derived from toasted oak

The reactions between (+)‐catechin and representative oak wood furanic (furfuraldehyde, 5‐hydroxymethylfurfuraldehyde and 5‐methylfurfuraldehyde) and phenolic (vanillin and syringaldehyde) aldehydes in a wine‐like model solution were studied and the corresponding condensation kinetics at pH 3.0 and 3.5 were compared. A comparative study on the reactivity of these two representative families of aldehydes towards (+)‐catechin showed a large difference between them. When incubated separately with (+)‐catechin at both pH values, the reactions were faster with furanic aldehydes than with phenolic aldehydes. In mixtures containing (+)‐catechin and individual aldehydes, new compounds were identified by high‐performance liquid chromatography (HPLC)/UV–visible detection, some of which were characterised by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI‐MS). The increase in solution absorbance with time was closely linked to these new products. Copyright © 2007 Society of Chemical Industry