Screwcap v Cork – the photographic evidence

What would happen if you bottled a Clare Valley Semillon under 14 different closures, including natural and synthetic corks and screwcap, and left them for 10 years? Would a simple photograph of unopened bottles tell a story? Certainly looks as though it does. The wine was made by Leasingham Estate and the study conducted by the Australian Wine Research Institute (AWRI). As the images show the wine under screwcap was the best preserved. But how did it taste? According to Peter Godden of AWRI "The wine under screw cap was classic aged Semillon and was wonderful to drink." Jamie Goode has blogged about the screwcap wine and the trial.

Screwcaps, corks and consumers

An interesting little study has been reported in ScienceNews from the spring meeting of the American Chemical Society. 2006 Pinot noir and Chardonnay from the Argyle Winery in Oregon were closed with natural cork, synthetic cork and three screw caps; the three screwcaps had a different lining. The chemical profile and dissolved oxygen content of the wine under each type of seal was examined at 6 month intervals over two years. In addition, volunteer tasters rated the flavor and aroma of the wines under the different closures. The conclusion? The synthetic cork and the cap lined with low-density polyethylene let in the most oxygen, but the tasters apparently could not detect any differences.

Should Wine be Bottled like Beer? Part 2

.........and then there is the other side of the coin where in order to go up market you make and bottle beer as though its Champagne!

Should Wine be Bottled like Beer?

In the most recent issue of Wines and Vines English wine writer Jamie Goode has a very readable article on Oxygen and Wine. Jamie covers several aspects including a research initiative being funded by Nomacorc, bottle closures and the technology being used to measure oxygen in wine. One of his conclusions is that the variability of oxygen pickup during bottling can be a significant problem for wine. But the most interesting point he discusses is that the beer industry has spent considerable time and effort to avoid the presence of oxygen in its product. In relating this to wine Jamie notes

George Crochiere gives some examples of the sorts of levels of oxygen that might be introduced to wine bottles during different filling procedures. In the worst-case scenario, a gravity-filled bottle sealed with a cork without any vacuum will pick up 2.6ppm oxygen during filling and have a further 1.8ppm oxygen in the headspace, giving a total of 4.4ppm.

If a vacuum filler is used and the headspace is evacuated, this figure will fall to just under 1ppm. If a screwcap is used and the bottle is filled using a vacuum filler, then pick-up in bottle filling is 0.6ppm. If liquid nitrogen dosing is used, headspace pickup is 0.7ppm; without this it is as high as 4.75ppm, giving an initial TPO (Total Pack Oxygen) of 5.36ppm. Crochiere points out that in the beer industry, the best-run bottling lines give oxygen pick-ups of between 0.05 and 0.15ppm, while average lines are 0.2-0.4ppm.

Obviously bottling under a vacuum and using a screwcap cuts the level of oxygen dramatically but not to the level of the best bottling achieved with beer. Even an average beer bottling line reaches levels that are better than the best wine practices. So why is wine not bottled like beer?

Clearly one argument is that we still don’t know what level of oxygen wine requires especially for maturation (cellaring). And we also don’t know whether different wines may need different levels of oxygen when placed in bottle. There are companies producing liners for screwcap that allow different levels of oxygen to pass. Different levels of oxygen, that does make the imagination wander. Just picture, one day Penfolds Grange may come in screwcaps of different colors. One color will signify a liner that allows little or no oxygen ingress/egress so you can cellar the wine for decades, another color may signify a liner that allow a little oxygen to enter so that maturation is hastened over a decade or less, and another may let in even more so that you can quaff your Grange as soon as you get it home from the wine store. And, of course, seeing as the Fosters Group makes both beer and wine your Grange for the cellar is likely to come with a twist top crown seal!