Fourteen different closures were included in the trial: nine synthetic closures from nine different sources, two source for technical cork (manufactured from natural cork with a synthetic component), one screw cap and two sample of natural cork. Five physical measurements were investigated up to 12 months post-bottling: headspace between the wine and the closure, extraction force, total extraction energy, maximum torque and ease of manual re-insertion. Generally the synthetic closure elongated upon insertion to a greater degree than natural cork. The maximum extraction force was measured from 48 hours following bottling through to the 12-month interval for bottles stored inverted under ambient temperature condition. The variability in this parameter of all the closures as a group more than doubled between 6 and 12 months of storage. Two different synthetic closures and one of the technical ones showed a maximum extraction force comparable to the natural cork. Total extraction energy was found to increase for eight and decrease for five of the closure during the 12 months following the bottling. Little change in the torque required to remove the closure was displayed by any closure over a 12-month period. At the 12-month testing interval the average in this measurement ranged from 0.20Nm to 0.83Nm for all closures except the synthetic NuKorc that was significantly higher. The ease of re-insertion differed between closures. Overall the natural cork and the technical One plus One were easy to reinsert compared with most synthetic closures.

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