422 M.A. Pozo-Bay ́ ́ on and G. Reineccius
Ta b l e 8 F. 1 β-Damascenone odour thresholds in ng/L. (reprinted with permission from Pineau
et al. (2007) J Agric Food Chem 55:4103–4108. Copyright (2007) American Chemical Society)
Water/ethanol solutiona Model white wineb Model red wine 1c Model red wine 2d Red wine
50 140 2100 850 7000
aHydroalcoholic solution prepared with a mixture water:ethanol (88:12 v/v) + 4 g/L tartaric acid.
pH was adjusted to 3.5 (0.5N KOH)
bPrepared after addition of charcoal to 1 L of Chardonnay wine to eliminate theβ-damascenone
cPrepared after evaporation of 1.5 L of Merlot wine in rotavapor. The residue was diluted with a
mixture water:ethanol (88:12 v/v)
dPrepared after evaporation of 1.5 L of Merlot wine in rotavapor until 2/3 of its volume and adjust-
ing 180 mL of ethanol and milliQ water till obtain 1.5 L of wine
compounds, they could be responsible for undesirable flavour changes thereby
producing wine of poor flavour (poor odour intensity and quality).
The impact of wine macromolecules on flavour quality/perception can be illus-
trated by some recent research. A termcalled Odour Activity Value (OAV) (ratio
of concentration to threshold) is widely used in the field to predict the potential
contribution of an aroma compound to overall product flavour. Pineau et al. (2007)
have pointed out that wine matrix components have not been taken into account
in the calculation of OAV of potent wine odorants. A consideration of interactions
between aroma compounds and wine macromolecules has demonstrated that some
components previously considered to be very important to wine aroma may not
be as important as thought. For example,β-damascenone has a very low percep-
tion threshold in a pure hydroalcoholic solution as compared to reconstituted red
wines where it is over 1000-fold higher (Table 8F.1). Thus, Pineau et al. (2007)
suggested that aroma impact data for wines based on OAV calculated using sensory
threshold values obtained in water or hydroalcoholic solutions may not be accurate,
and could be highly overestimated. This type of error can result in academic and
industry researchers focusing flavour research efforts on compounds thatare of little
importance and ignoring those aroma compounds of importance. It is highly desir-
able to understand how flavour interactions with the major components of wines
influence flavour perception.
8F.2.2 Effect of Specific Components on Wine Aroma
8F.2.2.1 Ethanol
Ethanol is produced during yeast fermentation of grape sugars, and it is, after water,
the major component of wines. Ethanol content is highly variable across wines
depending on the sugar content of the must and on the winemaking technology,
ranging between 10% and 15% for table wines to 18–21% for some young Porto and
Sherry fortified wines (Hermos ́ın 2003). It directly contributes to wine aroma and
overall flavour since it is substantially above its perception threshold (from 0.1 to
100 ppm) (Bayonove et al. 2000) At lower concentrations than those found in wines
(between 2% and 4%), it enhances the sour and sweet tastes, and also masks the