598 A. Bertrand and A.A. Beloqui
M-terbutyl phenoldibutylphtalateFig. 10.2Chromatogram of a wine contaminated by the release ofm-terbutylphenol and dibutyl
phthalate from the epoxidic lining of a tank
10.3 Defects Caused by Some Preservatives
10.3.1 Geranium Aroma
The addition of sorbic acid to a wine should always be carried out in the presence
of free SO 2 , since bacteria that are not inhibited by this acid can break it down to
2-ethoxyhexa-3,5-diene (Lacoste 1973; Crowell and Guymon 1975; Radler 1976).
The perception threshold of this ether in wines is 1× 10 −7g/L(W ̈urdig 1977).
10.3.2 Mustard Aroma
Allyl isothiocyanate (CH 2 =CHCH 2 N=C=S) has been studied as a contaminant in
wine from discs treated with this substance. It is used at the surface of tanks to
prevent the development of yeast velum, which is prohibited in most countries. We
did not find allyl isothiocyanate in any of the wines studied.
10.4 Exogenous Sulphur Compounds
10.4.1 Compounds of Technological Origin (Rubbery Flavor)
10.4.1.1 Benzothiazole
Benzothiazole is a sulfurous compound naturally present in wines at levels below
7
g/L (Keck 1989). At higher concentrations, the benzothiazole may be derived
from contamination by the rubber pipes.