NEW INSIGHTS INTO VOLATILE SULPHUR COMPOUNDS SCALPING ON MICROAGGLOMERATED WINE CLOSURES

Abstract

The evolution of wine during bottle ageing has been of great interest to ensure consistent quality over time. While the role of wine closures on the amount of oxygen is well-known [1], closures could also play other roles such as the scalping phenomenon of flavour compounds. Flavour scalping has been described as the sorption of flavour compounds by the packaging material, which could result in losses of flavour intensity. It has been reported in the literature that volatile sulphur compounds (VSC) can be scalped on wine closures depending on the type of closure (traditional and agglomerated cork, screw-cap, synthetic [2]). However, no studies have been carried out to correlate the permeability of agglomerated closures with the scalping effect. In this study, we studied the evolution of the scalping effect of 7 VSC on 4 micro-agglomerated closures in model and Shiraz wines.

In practice, each closure was fully immerged in 20 mL of wine containing a precise concentration of 7 VSC (13.3 µmol/L) and maintained at room temperature under stirring (300 rpm) for 7 days. Finally, the residual concentration of VSC in the wines was monitored after 1 h, 6 h, 3 days and 7 days by HS-SPME-GC-MS/MS. All experiments were performed in triplicate and a control experiment without closure allowed us to evaluate the losses of VSC due to chemical mechanisms in both matrices.

In general, the concentrations of VSC decreased in all experiments from 1 h to 7 days, regardless of the wine matrix, indicating a possible flavour scalping. In fact, the residual concentrations of VSC after 7 days of monitoring were significantly lower in wines containing a closure (2.1±0.5 µmol/L) than in the control experiment (6.3 µmol/L). VSC were rapidly degraded after 6 h of contact of both wine matrices with closures, but no significant effect of the type of closure was observed. Consequently, it seems that the permeability of the agglomerated closure could not affect the scalping of VSC.

From a quantitative point of view, a simple material balance allowed us to characterize the fate of VSC during simulated ageing conditions: