Wine Chemistry and Biochemistry

10 Aromatic Spoilage of Wines by Raw Materials and Enological Products 601

In the literature, a series of compounds are mentioned as possibly derived from

the breakdown of “thirame”, including:

• Dimethyldithiocarbamate (Jacob 1961)


• Dimethyldithiocarbamate, CS 2 , DMS and COS (Schmitt 1987)


• Isothiocyanate and H 2 S or ethylenediamine and CS 2 or ethylenethiouramide

or ethylenethiourea or ethylenediamine and COS and CS 2 (Marshall 1977;

Maujean 1989)

This passes through an intermediate, which usually has the formula C 5 H 9 NS 3 ,

but which does not appear owing to the action of the yeasts (Anocibar Belo-

qui 1998). This could be one of the two formulae presented (Fig. 10.4).

Analysis of wines from different chˆateaux and different harvests showed that

there are always high doses of carbon disulphide when this molecule is present,

although a correlation was not established (Fig. 10.5).

The sensorial analysis shows that, for CS 2 , the descriptors used by the tasters are

“sulphurous”, “rubbery”, “burnt” and “reduced”.

The perception threshold of CS 2 in water is around 20 g/L, a little lower than

that recorded by Spedding and Raut (1982) in white wines (38 g/L). Tasters can

recognise this substance at concentrations of around 150 g/L. However, at lower

levels, the aromatic tone of the wine changes and it tends to mask some fruity

aromas, while it can enhance the mouldy aroma or even that of volatile phenols

and the wine can be described as lacking limpidity.

Of all the wines studied, a large number contain concentrations of CS 2 far higher

than those we recorded, which could contribute to wine spoilage. Moreover, car-

bon disulphide can evolve in the presence of alcohol into ethyl monothiocarba-
mate, although we did not detect this compound. We have conducted experiments to

N

H 3 C

H 3 C

HC

SHC

CH

S S

Fig. 10.4Supposed molecular structures corresponding to the degradation products of thirame
by yeast