<p style="text-align: justify;">The assaying of oxygen in the headspace of a bottle combined with that of dissolved oxygen in the wine makes it possible to obtain the total oxygen per bottle. The first analyses performed at bottling show that 0.38 to 3.58 mg oxygen per bottle is trapped in the headspace. Operating conditions account for these substantial variations. Monitoring the oxygen contents in the liquid and gas phases of three batches of wine over a period of several months and the analysis of old bottles show that the headspace functions as an oxygen reserve for the wine, that is to say that as the wine uses oxygen, there is passage of the gas from the headspace to the wine. This is related to a movement towards a balance between the two phases as the partial pressure of oxygen in the gas phase is always greater than that of the liquid phase. Finally, this gas exchange kinetics within the bottle outweighs the kinetics of penetration of the bottle by oxygen in the external atmosphere, at least while the total oxygen trapped at bottling has not been used up.</p>

<p style="text-align: justify;">This paper presents a protocol for the sampling of gases and the measurement of oxygen by the means of a polarographic probe after bottle corking. Analyses of certified standard gases were performed according to the standard protocol of the Office International de la Vigne et du Vin to characterize the polarographic probe and gas chromatography (GC) methods. Finally, analyses of bottles of wine were performed to compare the both methods, together with a method based on the measurement of dissolved oxygen before and after agitation of the bottle of wine.</p><p style="text-align: justify;">The polarographic method displays greater sensitivity and a lower limit of quantification (LQ) than the GC method. Uncertainty was found to be 0.51 % with the probe method. Although the study showed that the results of the indirect method differed from those of the probe and GC methods, especially for high oxygen contents, it enables wine companies to measure oxygen in the wine and in the bottle headspace using the same apparatus.</p>

The management of dissolved and headspace gases during bottling and the choice of packaging are both key factors for the shelf life of wine. Two kinds of 75 cL polyethylene terephthalate (PET) bottles (with or without recycled PET) were compared to glass bottles filled with a rosé wine, closed with the same screwcaps and stored upright at 20 °C in light or in the dark. Analytical monitoring (aphrometric pressure, headspace volume, O2, N2, CO2, and SO2) was carried out for 372 days. After the consumption of O2 trapped during bottling, the total O2 content in glass bottles remained stable. A substantial decrease of CO2 and SO2 concentration and an increase of O2 concentration were observed in the PET bottles after 6 months because of the considerable gas permeability of monolayer PET. Light accelerated O2 consumption during the early months. Finally, the kinetic monitoring of partial pressures in gas and liquid phases in bottles showed contrasting behavior of O2 and N2 in comparison with CO2.

Aims: The management of O 2 , CO 2 and SO 2 at bottling and the choice of the closure are two key factors of the shelf life of wine in bottles before bringing them to market. The impact of four screw caps, two synthetic and two technical corks was evaluated on a red wine of Merlot/Tannat. Methods and results:Analytical monitoring (O 2 , CO 2 , SO 2 , aphrometric pressure, L*, a*, b*) was carried out during 538 days of storage at 20 • C. Two sensory analyses at 10 and 17 months completed the study.The wine was bottled with an average total oxygen content of 2 mg/L. The heterogeneity intra and inter procedure was controlled, including for the dissolved carbon dioxide content. Conclusion:Unlike closures with highest OTR, the two technical corks and the two screw caps with Saranex seal, harboring the lowest OTR, matched with the wines exhibiting a low total O 2 content at equilibrium (from 4 th to 18 th month), with more free SO 2 and less changed colour. However this OTR gradient (5 to 67 µg/d) observed through the physicochemical analyses was not necessarily confirmed by both sensory analyses performed. Significance and impact of study:This study puts into perspective the impact of OTR closure on sensory characteristics evolution of wine consumed during the first two years, especially when the total oxygen at bottling exceeds 1.5 mg/L.

Aims: The management of O2, CO2 and SO2 at bottling and the choice of closure are two key factors of the shelf life of bottled wines before bringing them to market. The impact of eight closures (four screw caps, two synthetic stoppers and two technical stoppers) was evaluated on a red Merlot/Tannat wine. The results of a rosé wine are also discussed.Methods and results: Analytical monitoring (O2, CO2, SO2, aphrometric pressure, L*, a*, b*) was carried out over 538 days of storage at 20°C, along with two sensory analyses at 10 and 17 months. The average wine total O2 content at the time of bottling was 2 mg/L. Intra- and inter-procedure variability was controlled, including for dissolved CO2 content.Conclusion: Unlike closures with the highest Oxygen Transmission Rate (OTR), the two technical stoppers and the two screw caps with Saranex seal, harboring the lowest OTR, matched with the wines exhibiting a low total O2 content at equilibrium (from 4 to 18 months after bottling), with more free SO2 and less color change. However, the OTR gradient (5 to 67 µg/d) observed through the physicochemical analyses was not necessarily confirmed by the two sensory analyses.Significance and impact of the study: This study puts into perspective the impact of closure OTR on the sensory characteristics evolution of wine consumed within the first two years, especially when total O2 at bottling exceeds 1.5 mg/L.