A Comparison of Wine Preservation Methods

Günther FinkAlex Healy
gfink (at) hsph.harvard.eduahealy (at) fas.harvard.edu


Abstract
We tested three common methods for storing unfinished bottles of wine: (1) simply recorking the bottle, (2) using the VacuVin pump and (3) using the "Private Preserve" blend of gases. All resealed bottles were stored in a refrigerator for three days and then tasted (blind) alongside samples from freshly-opened control bottles.

We found that simply recorking the bottle was quite effective, although the VacuVin pump performed better. Remarkably, the "Private Preserve" system was found to be inferior to simply recorking the bottle (for both wines used in the experiments).



Introduction
Volumes have been written on the ideal conditions for storing unopened bottles of wine, but a more pragmatic question for most wine-drinkers is that of how to store leftover wine from an unfinished bottle. The easiest method is to simply recork the bottle; however, various more sophisticated methods exist including using a vacuum pump to reduce the amount of air in the bottle, blanketing the wine with inert gas or decanting the leftover wine into a smaller bottle (with little or no room for air).

In this work, we undertake a controled experiment to gauge the performance of three popular wine-preservation methods: (1) simply recorking the bottle, (2) using the VacuVin pump to remove most of the air in the bottle and (3) blanketing the wine with the Private Preserve blend of gases (Nitrogen, Argon and Carbon Dioxide).
Standard Corks VacuVin Pump Private Preserve
It is well-known that the main reason that wine "goes bad" is over-exposure to oxygen, and therefore the above methods seek to reduce the amount of oxygen that comes in contact with the wine. It is also well-known that wine (as with most any food/beverage) will spoil more quickly at higher temperature, so storing the leftover wine in a refrigerator is advised.

The Experimental Setup
We selected two contrasting wines for the tasting: The Casa Lapostolle, Sauvignon Blanc, 2005 (white), $10 and The J. Lohr, "Seven Oaks" Cabernet Sauvignon, 2003 (red), $13. We purchased two bottles of each wine.
For each of the two wines, the first bottle was carefully divided among three clean wine bottles (1/3 of a bottle, or about 1 cup, in each). The second (unopened) bottle of each wine was kept as a control sample for the tasting.
The bottles were then sealed using the three preservation methods: (1) simply recorking the bottle, (2) creating a partial vacuum using the VacuVin pump and (3) using the Private Preserve spray can.
Finally, the six sealed bottles were placed in the refrigerator (at about 34F) for three days.


The Tasting
Three days after sealing the bottles, we removed them from the refrigerator and let them come to the same temperature as the control bottles (50F for the white wines and 62F for the red wines).

We used four identical Riedel wine glasses (the Vinum series Bordeaux glasses), the bottoms of which were labeled with the sample type ("C" = "cork only", "V" = "VacuVin", "G" = "Private Preserve Gas", "N" = "New (unopened) sample").
We shuffled the four samples in such a way that neither of us knew which sample was which, and then tasted them (whites first, and the reds an hour later).


Results
The single most striking result was that both samples (white & red) stored using the Private Preserve gas were markedly worse than all the other samples. Indeed, the aroma/taste of these samples was not simply that of an oxidized (i.e. spoilt) wine, but rather included some unpleasant, chemical and generally "off" aromas (burnt rubber? tar?). Perhaps this supposedly "harmless" blend of gasses reacted adversly with the wine? It is also worth noting that these samples had many more surface bubbles than the other samples (see the second glass from the bottom in the photograph).

For the three remaining white wine samples, the results were as one might expect: the newly-opened sample had the freshest and most focused character, with the VacuVin sample coming in a close second. The recorked sample survived remarkably well, although was noticeably less fresh and flavorful than the newly-opened and VacuVin samples, at least in a side-by-side comparison.

For the reds, we noticed differences among the three remaining samples, although they were difficult to classify as the wine continuned to evolve in the glass. We originally identified the recorked bottle as having the "roundest" flavor and the freshly-opened sample as being a little "harsh", with the VacuVin sample somewhere in between. Fifteen minutes later (alas, only after we looked at the identifying labels on the bottoms of the glasses -- so we cannot claim that these tastings were conducted blind), we found that the freshly-opened sample had "opened up" considerably, and was superior to the VacuVin and recorked samples (which had now begun to fade and lose their appeal), as one might have expected.

Conclusions and Future Work
We found that simply recorking an unused bottle of wine and placing it in the refrigerator is quite effective, but the use of the VacuVin pump was a noticeable improvement.

The poor performance of the Private Preserve gas is counterintuitive and certainly does not agree with the anecdotal evidence of many wine-writers. We feel that this warrants further study, and in particular, we hope to conduct a similar experiment comparing the Private Preserve gas with a pure-nitrogen system such as the Wine Keeper system (again, using unopened bottles as a control).

Of course, there are many further tests that can be conducted to corroborate and/or complement this experiment. Perhaps the most effective preservation methods depend of the age or style of the wine? How do various preservation systems work at room-temperature? And the list goes on.

We hope to address these and other questions in future experiments of this kind.