10 Aromatic Spoilage of Wines by Raw Materials and Enological Products 597
In an important study on alcoholic drinks presented to the OIV, Bertoli et al.
(2004) studied different phthalates (dimethyl, diethyl, diisobutyl, dibutyl, benzyl,
butyl, bi 2-ethylhexyl, dioctyl). They detected the constant presence of these com-
pounds in alcoholic drinks due to environmental contamination and recommend that
special care be taken when choosing contact materials (for pipes, tanks, etc.). In
any case, the levels present in wines rarely exceed tens of g/L; for dibutyl phtha-
late they are lower than 10 g/L and for the other phthalates are often below the
detection limit.
10.2 Defects Caused by Residues and Wine Materials
10.2.1 Bitter Almond Flavor
Wines stored in vats lined with epoxy resins can present unusually high levels of
benzoic aldehyde (several mg/L). Benzylic alcohol is both a plasticizer and diluent
of these resins. Its conversion into benzaldehyde can be due (Blaise 1986) to the
action of an exocellular enzyme ofBotrytis cinereacalled Alcohol Benzylic Oxidase
(ABO, E.C. 1.1.3.7.) responsible for this oxidation process (Blaise and Brun 1986).
10.2.2 Styrene or Vinylbenzene Flavor
Styrene flavor is one of the commonest defects caused by the polyester “plastic
material” of the tanks used to store the wines (Brun et al. 1982), especially in plastic
vats. It gives off a plastic or burnt rubber aroma and has a perception threshold of
around 100 g/L.
10.2.3 Defects Derived from the Epoxy Resins
The solvents or diluents applied to line the tanks can affect wine quality even at very
low doses, of the order of a few g/L. These should be completely removed before
the tanks are filled with wine.
These often correspond to aromatic hydrocarbons (xylene, toluene, ethylben-
zenes, etc.) and ketones (methyl-ethylketone, methyl-isobutylketone, methyl-propyl-
ketone, etc.).
There are also other alterations of the same origin that produce other flavor
defects: – a very strong phenol flavor produced by the resin monomers or impu-
rities (cresols, phenol, 2-ethylphenol, 3-ethylphenol,m-terbutylphenol (Fig. 10.2),
2,4-dichlorophenol, etc.).