596 A. Bertrand and A.A. Beloqui
10.1 Contaminations of Technological Origin
10.1.1 Hydrocarbonates and Derivatives
It is not recommended to resurface tarmacked roads in the weeks prior to the grape
harvest to protect wine quality, since this process can produce strong tar-like or
naphthalene flavors and aromas. Any contamination by diesel-oil type hydrocarbons
can render wines undrinkable.
Oil leaks from the hydraulic jack of the harvesting machines and presses can also
contaminate the grapes (Fig. 10.1).
Another source of contamination corresponds to fluid leaks from the refrigerat-
ing apparatus inside the tanks, producing excess propan-1,2-diol. This compound,
naturally present in wines in tens of mg/L, does not produce an aromatic defect, but
does give a slightly sugary flavor. Maximum levels should be limited to 150 mg/L
in still wines and 300 mg/L in sparkling wines, according to the OIV, and contami-
nated wines must be destroyed. It is strongly recommended not to use glycol and/or
diethylene glycol as coolants owing to their toxic nature.
10.1.2 Phthalates
Phthalates are plasticizers that can migrate from the materials in contact with the
wine. Although they do not cause pronounced changes in flavor they can reduce the
limpidity and freshness of wine.
Fig. 10.1Chromatogram of wine extract mildly contaminated with diesel oil. The peaks of ions
155 and 170 are typical of this type of contamination (naphthalene derivatives present in all the
hydrocarbons)