602 A. Bertrand and A.A. Beloqui
Control0501001502002503003501 2 3 4 5 6 7 8 9 10 111213141516171819
Samplesμg/LCS2
Peak AMethomyl
22 JulyThirame
27 JulyThirame
6 AugustFig. 10.5Influence of phytosanitary vine treatments on the amount of residues in different
Beaujolais wines. Peak A: C 5 H 9 NS 3
remove CS 2 from wine. Treatment with copper sulphate, which gives good results
with compounds containing a thiol group, do not work with CS 2. The only treatment
that has proven quite useful is to bubble nitrogen through it.
10.4.2.4 Products Derived from the Sulphur Used in Vine Treatment
Sulphur is a phytosanitary product that has been used for some time in the treatment
of grapevine powdery mildew (Uncinula Necator). It can be used in powder form
to stop the spread of this disease (sublimable or sulphur flower), generally in large
doses, or dissolved (soluble sulphur).
There are few data in the literature aboutthe amount of elemental sulphur residue
in the vine. Thomas et al. (1993) found sulphur concentrations in the grapes always
at concentrations lower than 3 g/g of grape, equivalent to 3.4 mg/L of sulphur in the
musts for vine treatments of 13 kg/ha. If the treatments are carried out before ripening,
as they should be, the concentrations found as residue are between 0.9 and 1.7 g/L.
At least part of the hydrogen sulphide, H 2 S, was formed in the wine by the reduc-
tion of elemental sulphur (Maw 1965; Wainwright 1971; Eschenbruch 1974; Sch ̈utz
and Kunkee 1977; Wenzel et al. 1980; Wenzel and Dittrich 1978, 1983; Stratford
and Rose 1985; Colagrande et al. 1988; Thomas et al. 1993). Below, we show the
mechanism of this reaction starting with elemental sulphur:
2R−SH+S →R−S−S−R+H 2 S
Thomas et al. (1993) added from 0 to 3.4 mg/L of sulphur to musts that are
fermented using different yeast strains. They did not find any correlation between
residual sulphur and the amount of H 2 S formed. Other authors, however, found a
dose of residual sulphur higher than 1 mg/L. The amounts of H 2 S formed exceed