Highlighting the several chemical situations of Dimethyl sulfide in wine

Abstract

Dimethyl sulfide (DMS) is a compound that accumulate in wine for the early years of ageing 1. During this stage, which is often carried out in the bottle, the environmental conditions are conducive to the release of DMS from its precursors, already present in grapes2. DMS has long been associated with unpleasant odours of cabbage or green olives but technological advances in analytical methods have made it possible to quantify this compound in smaller quantities in wines, allowing scientists to consider it as an aromatically interesting molecule. Recently, DMS has been identified as a central component of ageing bouquets for participating to their complexity and typicity3,4. Indeed, it contributes to the “truffle” and “undergrowth” odours of wines and its presence intensifies the fruity aromas and more particularly of the blackcurrant notes5. Also during the tasting, DMS acts as an enhancer and an inhibitor of aromatic notes successively and alternatively6. On the other hand, recent laboratory tests have shown that a wine spiked with a known amount of DMS will not have the same smell as a wine naturally rich in the same amount of DMS. Thus, the hypothesis of the existence of weak bonds between DMS and some components of wine matrix was posed.

Several components whose combined effect may be possible was chosen for explore hypothesis. Model wine solutions were made with additions of the different target compounds and DMS. Free DMS was determined by SHS-FPD at different days according to established kinetics. Then, the sorption mode was characterized as well as the sensory impact of DMS in different matrices. 

Experiments showed that in the model solutions containing grapes tannins, the free DMS decreased over the days compared to the control without tannins where the amounts of DMS remained the same from 0 to 15 days. Differences in the decrease of free DMS in the headspace of the samples were observed and measured depending on the tannin fractions tested and the concentration added to the model solution. Then, the sorption mode employed between DMS and tannins studied would be a cooperation sorption. The characterisation of DMS in water, wine and according to its mode of service was carried out which made it possible to highlight the multiple odours of this compound and its essential contribution, whatever its form in the wine, to the aromatic characters of this one as of the opening of the bottle.