There are several possible explanations: the adsorption of anthocyanins to the cellwalls of the
used yeast strain (Morata, Gomez-Cordoves, Colomo, & Suarez,
2005) and condensation reactions with acetaldehyde (Bosso &
Guaita, 2008).
Perhaps the Saccharomyces strains involved in the
2008 spontaneous fermentations had a greater tendency to adsorb
these molecules than the strain used in the inoculated processes.