A technique to remove air from cork wine closures

Cork manufacturers have tried too hard to differentiate themselves through the permeability of their corks, whilst 80% of the quantity of oxygen dissolved in the wine two years after bottling comes from desorption”, says Benoît Villedey, assistant head of the wine department at the Champagne wine marketing board (CIVC).

The phenomenon is almost identical for all corks, regardless of whether they are natural or micro-agglomerated. “Over 3 months, the cork releases 2.5 to 3 mg of O2 per bottle”. Complete filling of the headspace at disgorgement with inert gas during jetting makes no difference.

After three years of confidential trials, Villedey and his team have been able to eliminate this oxidative shock. “We managed to inert the finished corks by storing them for three months in an isobaric tank, maintaining nitrogen overpressure and renewing the volume of gas every week”, he explains.

The corks did not start to refill with O2 until six hours after being removed from their nitrogen-filled atmosphere and did not lose their physical properties. “Once this huge input of oxygen has been eliminated, the influx of oxygen through the cork follows that encountered by the same wine on the lees”, says Villedey, who is sure that adding inert gas to corks combined with jetting would enable winegrowers to forego sulphites during disgorgement.

The Champagne marketing board now needs help from cork and bottling block manufacturers to turn this discovery into a reality out in the field.