First Study to Analyze Liner Impact on Wine Evolution

The scientific study is managed and supervised by EXCELL Laboratory, following a strict protocol and close monitoring to ensure the conditions are consistent for greater accuracy.

08/06/07 First Study to Analyze Liner Impact on Wine Evolution UCP, MGJ and EXCELL Laboratory have partnered for the first scientific study to examine the influence of liner permeability on the evolution of wines with varying reductive potentials when using a screw cap closure with different liners. Four wine varietals were selected and bottled in Bordeaux, France on October 13, 2006.

Over the next 18 months, the evolution of each wine, using various liner and closure combinations, will be observed and analyzed. Results from the study will provide valuable insight on how a wine develops under a screw cap closure. The project is intended to develop a series of scientific arguments making it possible to reason why a particular liner may be a better choice for a particular wine.

“Previous studies indicate synthetic corks have excessive oxygen permeation in comparison to natural cork, which results in increased oxidation and premature ageing in the bottle,” said Pascal Chatonnet, founder, EXCELL Laboratory. “As a result, several winemakers using screw caps may try to minimise reduction through pre-bottling processing. We believe that it comes down to the correct chemical make-up of the wine combined with an intermediate liner solution.

The capacity of a wine to evolve in a reductive or oxidative way is influenced by the wine’s composition, the conditions when preparing the wine for bottling and the closure system. Until now, studies have focused on wine closures and levels of oxygen permeation, vastly overlooking a wine’s reduction potential. Recent research indicates closure permeability alone does not guarantee a positive or negative evolution in the bottle. The coupled effect of closure choice and the potential of the wine to resist oxidation and generate reductive odours must be taken into account to determine "the right closure for the right wine".

In order to conclude the appropriate closure solutions for a wine, the composition of wine was studied to determine reductive and oxidative potentials. After careful analysis, the study partners selected a red and a white wine with low reduction potential (Merlot and Sauvignon) and a red and a white wine with a high reduction potential (Syrah and Sauvignon).

The study partners selected two liners from MGJ’s œnoseal range, the saranex and the tin-saran liner, both in a UCP VinGuard/30x60mm screw cap closure, as they are products currently available in the market.

The closures were measured in controlled conditions (reference method ASTM) to determine the different levels of low permeability. Each wine group, low and high reduction potential, were bottled with UCP VinGuard 30x60mm aluminium closures fitted with a tin saran liner and a EPE saranex liner. The control group of wine was bottled using the Nomacorc “Classic”, a synthetic cork with low oxygen permeability in comparison with other synthetic corks.

“We know that a screw cap is already an acceptable closure for wine, but there has never been a scientific examination of the appropriate liner for wines that have strong or weak potential for reduction,” said George Thomson, Key Account Director, UCP. “Now we can help wine makers determine the best liner for a screw cap closure for an individual wine, which will result in greater quality consistency and a better consumer experience with the wine.”

The scientific study is managed and supervised by EXCELL Laboratory, following a strict protocol and close monitoring to ensure the conditions are consistent for greater accuracy. The evolution of the wines will be evaluated both scientifically and through sensory observations throughout the study.

Substances positively or negatively influencing the taste (oxidative and reductive volatile compounds), coupled with measuring dissolved oxygen and descriptive sensory analysis will be documented when assessing the composition of the wines. Special attention will be paid to the volatile sulphur compounds implicated in the formation of unpleasant reductive odours, the composition of the wine in terms of anti-oxidants, and sensory analysis. These compounds will be analysed using sophisticated and specific dosage techniques such as gas chromatography, mass spectrometry, flame photometry and specific enrichment techniques, as well as by tasting.

“MGJ and UCP have a long history of serving the wine industry. We anticipate the results of this study will allow us, as packaging partners, to better serve the wine industry,” said Stephane Triquet, Managing Director, MGJ. “Having scientific data to help explain the performance of the closure will help winemakers achieve their goal to make better wine.”