Role of aldehydic derivatives in the condensation of phenolic compounds with emphasis on the sensorial properties of fruit-derived foods.

The reactions between (epi)catechin, mavidin 3-O-glucoside, and some aldehydes were investigated by LC/DAD and LC/ESI-MS analysis. The obtained results showed that the acetaldehyde-mediated condensation occurred more generally and glyoxylic acid, furfural, and 5-(hydroxymethyl)furfural (HMF) react in the same way in the first stages of the reactions. In terms of reactivity, reactions were faster with acetaldehyde than with glyoxylic acid, furfural, or HMF, where the reactions were slower. In the case of acetaldehyde, the obtained purple derivatives were more predominant and stable than the colorless adducts and no xanthylium salt was detected. Interactions involving glyoxylic acid yield purple adducts, which were obtained in small amount compared to the colorless ones. The latter were shown to proceed to more polymerized and yellowish derivatives. Finally, in the case of furfural and HMF, purple compounds involving flavanol and anthocyanin units were detected, and colorless compounds were shown to be predominant and to yield yellowish xanthylium salts.