IMPACT OF STOPPER TYPE ON OXYGEN INGRESS DURING WINE BOTTLING WHEN USING AN INERT GAS COVER

Many articles evaluating oxygen ingress for different wine stoppers have been published. However, none of these have studied the impact of the stopper type on oxygen ingress during the bottling process. This study tested a range of commercially available stopper types on oxygen entry into headspace during bottling.Oxygen concentration in the headspace was measured using the Winkler method. Stopper type significantly (P<0.05) affected oxygen introduced into the headspace. Oxygen concentration correlated well with the volume and the overpressure of the headspace and was also strongly influenced by stopper height. Bottles sealed with natural cork had the lowest headspace oxygen concentration (1.31–2.12 mg/L) despite these stoppers having a lower height (38 mm) than the others tested. Non-cork stoppers were associated with higher oxygen concentrations, probably because they generated higher overpressure. Bottles sealed with screw cap and synthetic stoppers had the highest oxygen concentration (3.29–3.82 mg/L) and, in the case of screw caps, this was probably a result of greater headspace volume. Headspace oxygen concentration for the synthetic stoppers and the screw cap was approximately equivalent to the oxygen entrance through natural cork during the first 8–10 months of ageing. Stopper type can affect oxygen ingress during bottling because of the changes in headspace volume and overpressure.Along with permeability, stopper selection should also consider the effects of stopper type on the amount of oxygen that initially enters the headspace. If the bottler is not equipped with an efficient vacuum and/or inert gas system, the impact of the stopper type on the entry of oxygen is an important consideration. (We recommend that you consult the full text of this article)