by Becca•March 23, 2017•Comments turn off on Alcohol Evaporation indigenous a Glass that Wine over Time: Potential ramifications for wine Competition Judging and also Outcomes

It is a simple matter of physics that once you have actually a liquid exposed to air, there is going to be part evaporation that sorts. A glass of water will ultimately evaporate over a long duration of time if that left someplace the end in the open. With wine, which is a mixture of water, alcohol, and also a bunch of other stuff, the exact same phenomena applies, despite the alcohol and also water will likely evaporate at various rates because of the physics properties of every compound. Just just how much alcohol evaporates from a glass the wine sit on the table? and is it even sufficient to notice any distinction as girlfriend drink it?


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Photo courtesy Flickr user Jessica Spengler


While this principle is simply a issue of simple physics, there yes, really hasn’t been very much research on the subject in the peer-review arena. Research studies have presented that the slim film of wine that deserve to be viewed along the sides of a alcohol glass (“wine tears”) is the an outcome of the evaporation that alcohol (also known as the “Marangoni effect”), though these studies never ever specifically measure the level of alcohol remaining in the glass to watch if any type of noticeable transforms occurred.

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Additionally, it is well-known that the alcohol contents of a wine can significantly influence the aromatics the a wine (as fine as other sensory characteristics), with certain alcohol levels well-known to some winemakers together the “sweet spot” result in the finest balance, and also any deviation exterior of that sweet spot outcomes in lessened sensory quality.

A study released in September 2016 in the Journal of agricultural and Food Chemistry, aimed to study this phenomenon further, by measure up the alters in alcohol contents in a alcohol glass end time, and also to determine if these transforms had any type of effect on the sensory qualities of the wine or not.

Brief Methods

This research employed three separate trials:

Trial 1

A 2014 Cabernet Sauvignon was put in ISO typical XL5 wine glasses at a volume of 50mL/glass.

Three separate treatments were applied:

The glass was covered with plastic lids.The glass continued to be uncovered and was inserted on a lab bench v minimal air flow (The glass continued to be uncovered and was exposed to consistent airflow (30.5L/s).

Ethanol content, wine density, and changes in mass were monitored in ~ 15 minute intervals in between 0 and also 120 minutes, then likewise at 240 minutes and also 360 minute after the psychological began.

Trial 2

2 white table wines, 2 red table wines, and 2 strengthened wines were inserted in ISO conventional XL5 wine glasses at a volume the 50mL/glass.

The very same treatment conditions as was performed in psychological 1 were repetitive in trial 2.

Ethanol content, alcohol density, and also changes in mass were monitored in ~ the start of the trial, and also then again 120 minute later.


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Trial 3

In this trial, glass form and volume that wine to be examined.

The 2014 Cabernet Sauvignon (the exact same as was offered in psychological 1) was put into 3 different varieties of glasses:

The ISO standard XL5A sparkling alcohol fluteA Riedel Ouverture Magnum

The therapies were the same as in Trials 1 and 2, though because that Trial 3, and additional glass the 100mL (in the ISO standard XL5 glass) was included.

Ethanol content, alcohol density, and changes in mass to be monitored in ~ the beginning of the trial, and then again 120 minute later.

Wine glass height, surface area of wine, and also diameter that the glass opening were measured.

Sensory Analysis

A dashboard of 18 judges was made use of for the sensory analysis section of this study.

The wines provided were native Trial 1 at the 120 minute mark.

Wines were presented come the judges in covered glasses and also in random order. The judges to be asked just to smell the wines and determine which one(s) were different (if they differed at all).

Other Analyses

Volatile compounds (including esters and alcohols) in the wines to be measured and analyzed using gas chromatography-mass spectroscopy.

Selected Results

Trial 1

No changes in ethanol content, density, or mass were found in wines that were covered.With uncovered wines, far-ranging differences in ethanol contents were provided within 15 minute of the attempt start.After 6 hours, the wine exposed to minimal airflow lost 1% alcohol by volume (abv), had actually a slight increase in density, and also lost close to 1g the mass.After 6 hours, the wine exposed come a steady circulation of air lost 3.2% abv, had boost in density, and lost close come 3.5g the mass.

Trial 2

Results native Trial 2 to be pretty lot the exact same as they to be in psychological 1.Initial alcohol content did not seem come influence how much alcohol was shed over the food of the 2 hour trial.

Trial 3

As with both trial 1 and also Trial 2, covered wines witnessed no changes in ethanol content, when uncovered wines differed significantly.The bigger Riedel Ouverture Magnum glasses observed the biggest loss of abv.Headspace volume was strongly associated with alcohol loss.Taking the over two results, if the larger opening the the glass influenced abv loss, the volume that wine inside the glass likewise influenced this loss, in order to glass size alone no the just player here.

Sensory & chemistry Analyses

13 that the 18 judges were able to determine the glass v the reduced alcohol content.11 the end of 15 volatile compound analyzed were uncovered to be considerably lower in the uncovered wines exposed to stable airflow.Losses observed included:64% because that ethyl octanoate.100% because that 2-methylpropyl acetate and also hexyl acetate (the researchers provided these 2 were currently quite short to begin with).21% because that hexanol.38% because that ethyl decanoate.

Conclusions

Overall, the results verified that several of the alcohol in a glass the wine will evaporate in as at an early stage as 15 minute after being set out and also exposed come airflow, despite it took as much as 2 hrs for the alcohol come drop 1% in those wines exposed to the biggest airflow. ~ 2 hours, many of the judges were able to pick out the wine that had actually been sit out. ~ 6 hours, alcohol level in the wines dropped upwards of 3.2%abv.

For every job consumers, ns imagine most aren’t milking a single glass that wine end the food of 2 to 6 hours, therefore they are most likely drinking the fast sufficient such the the tiny drop in abv would be left unnoticed. That being said, because the study just did the sensory evaluation at the


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2 hour mark, ns can’t be completely certain the someone can not tell the distinction at an previously time point. Having the judges sample the wines at the previously time suggest would paint a clearer picture on the subject.

Where the results of this study perform come in come play, however, is in the case where you have a major judging event, such as a wine competition or some other occasion where there is the opportunity of glasses that wine gift left out for a longer period. Some wine competitions have actually strict protocols where they keep the wine glasses extended after they have been poured, yet for those competitions the don’t rental this practice, over there is a readjust that last results of the competition can be impacted due to far-reaching sensory changes of several of the wines that have been sitting out for a while.

With many competitions or other skilled tastings, efforts are regularly made to try and limit the variety of wines a solitary judge is responsible for evaluating, however, that occasionally can’t take place for logistical purposes, and also a solitary judge ends up having to taste a significant number the wines the take increase a longer chunk that time. If the wines space poured into glasses and also not subsequently covered, the results of this research would show that the alcohol content as well as the aromatic volatile components of the wine would certainly change, leading to diminished quality that the wine in the glass and also therefore not representative the the wine the was gotten in into the vain or tasting.

It should also be noted that the size/shape that the wine glass showed up to affect the alcohol/volatile content of the wine, with bigger openings top to greater evaporation (and thereby better volatile loss) end time. This result could likewise be necessary for wine judging, particularly again if a alcohol is going come be setup out for a long duration of time.

Of course, the results of this study would imply that every you have to do is placed a sheathe on the wine glass to avoid any of these transforms in the chemical and also sensory attributes of the wine, so about theory you deserve to use everything glasses girlfriend want and also let the wines sit the end for as long as you desire (until a point, ns sure…) and the wine will certainly be the very same as that was as soon as it was first poured.

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Source:

Wollan, D., Pham, D-T., and Wilkinson, K.L. 2016. Alters in wine Ethanol Content because of Evaporation from wine Glasses and Implications because that Sensory Analysis. Journal of farming and Food Chemistry 64: 7569-7575.