Among the volatile compounds (Table 1), the acetaldehyde concentrations
were low in all of the trials. For the other volatile compounds,
the amylic alcohols (i.e., 2-methyl-1-butanol, 3-methyl-1-butanol) had
low concentrations in all of the trials, and considering the sum of these
two alcohols, this was lower in the pure Z. florentina culture (94 mg/L)
than the pure S. cerevisiae culture (195 mg/L). In particular, there were
significant differences among the trials for 3-methyl-1-butanol, but not
for 2-methyl-1-butanol. These different production levels influenced the
relevant concentrations in the mixed fermentations (which when
combined ranged from 134 to 160 mg/L), which suggests an additive
effect due to the low concentrations produced by the pure Z. florentina
culture fermentations. Moreover, in all of the mixed fermentations,
there were significantly increased concentrations of 2-phenylethanol
(32–40 mg/L) (which gives a rose-like flavour to wine) compared to
both of the pure fermentations (22–24 mg/L). This would suggest a
clear synergistic effect that was derived from the interactions between
these two yeast, confirming the findings of our previous study (Domizio
et al., 2011a).