Many whiskey drinkers claim that if a whiskey tastes bad when first opened, just pour a serving out, re-cork it, and then it will soon “open up” and taste much better. But for that to be true a lot of oxidation and chemical changes would suddenly have to occur .
There are just two problems with this: (A) Nope, the whiskey isn’t significantly oxidizing more in just a couple of weeks, and (B) it doesn’t even taste better.
Think this through carefully – that “bottled” whiskey has spent most of it’s life in a porous wood barrel, with oxygen flowing in and out it daily, usually for at least four years, and sometimes for ten or twenty years! If any oxidation and chemical change was going to happen, it would have happened during that long time.
Check their logic: So adding just two more weeks will often change the flavor for the better? If that were true, then the implication is astonishing! So just about every whiskey maker mistakenly ages their whiskeys just two weeks short of the time for a better flavor to develop. Welp, how likely is that?
Now, before we go on, please note that this article addresses only a specific claim: that a couple of weeks after a bottle is opened it will change in flavor.
This article is not claiming that no further significant change can occur to the contents of the bottle. Indeed, changes over longer periods of time – years – are indeed possible! This is due to a number of reasons, including evaporation of alcohol, increasing ratio of air-to-liquid, exposure to direct sunlight, and temperature swings.
In part (A) Cody Corbin helpfully explains why the idea of whiskey oxidizing over just a few weeks is a myth (And further down, see parts B and C for some really well done studies about this topic!)
(A) Is whiskey oxidizing after a couple of weeks?
Hello all. PhD chemist here. I’ve been wanting to put a post about the myth of whiskey “oxidizing”. From what oxidizing means, which in laymen’s terms is “reacts with oxygen”, this just chemically isn’t very likely.
Think of the process of making bourbon” First you distill the mash. That distillation is done in air at high temperatures. Any compounds that could have be oxidized should theoretically happen there already.
What kind of compounds are giving us whiskey flavors? Check out this beautiful infographic of Esters and their Smells by James Kennedy.
Next the barrel aging. You’re putting that whiskey in a charred oak barrel, which in and of itself is the most oxidized form of the wood since you’re literally burning it in air. None of those compounds have the capability to oxidize further, they’re done.
There’s also air present in the barrel during the entire aging process of years. So, after all that, how can any oxygen do anything to whiskey in a glass bottle? It’s done!
Q: But every time you open the bottle to have a pour, new air enters the bottle.
A: It’s not the new air going in the bottle that’s making the difference, it’s the escape of the headspace in the bottle when it’s open that makes the difference. Alcohol is more volatile than water, so it (in the gas form) takes up much of the space above the liquid. When a bottle is opened and that escapes, more alcohol fills the space after the bottle is sealed which lowers the proof. This happens every time the bottle is opened. It’s the same thing like adding a drop of water to a glass of whiskey and all the changes that can cause. You’re not adding water when you open a bottle, but the loss of alcohol makes the water more abundant, which is the same thing.
Q: How would a wine vacuum sealer impact this? Better, worse, no change? I’ve done this before, and the vacuum remains even after a month plus, but didn’t make any other observations.
A: Vacuum will pull even more alcohol out each time, so worse. The higher the ABV the higher the difference most likely. The vacuum may seem to be similar, but I can guarantee you it’s pulling more alcohol out. It’s physics. Wines being only 15% ABV don’t do it as much, or it’s not noticeable because wine is drank within a couple of days after opening.
Q: Aside from very slightly lowering the ABV, what really does adding a drop of pH neutral water do to whiskey?
A: Changing the ABV changes the solubility of all the flavor compounds present, both from the grain and from the barrel. Example: ever left some whiskey in a glass overnight? You come back to it being cloudy. This is because a lot of the alcohol has evaporated – leaving relatively more water. Some of the organic compounds that were soluble in the originally higher alcohol solution now clump together, as they are less soluble in this somewhat higher water solution.
(B) A blind taste test on how flavor will or won’t change over time
, see Did my bourbon change in the bottle? 1 year test by consumer advocate Wade Woodard. His well-conducted blind taste test shows that even after you open a bottle and let air in, even when a year passes, there is no detectable change in the whiskey’s taste! When people say “my bottle opened up and tastes better!,” that’s really just the placebo effect.
(C) Breaking Bourbon blind taste test on how flavor will or won’t change over time
In this experiment, Bourbon storage experiment from Breaking Bourbon, blind taste tests don’t reveal any significant changes in a few weeks after a bottle is opened. No magical “opening up” that can be revealed or replicated. But oh yes, once the liquid in a bottle falls to a lower level and more air gets in, over a longer period of time, some flavor changes can happen; lots of alcohol escapes at this point. and some cogeners begin to clump up in the now higher-water liquid. Most importantly, exposure to direct sunlight has a deleterious effect on whisky quality.
(D) Sku’s taste test on how flavor will or won’t change over time
Even over a two year period, Sku found no significant change in flavor, unless the bottle was mostly empty of liquid and more filled with.
http://recenteats.blogspot.com/2011/03/whiskey-wednesday-whiskey-age-and.html
(E) Some more discussion (will be adding more over time) here
straightbourbon.com Bourbon and air
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Personally I distrust most of the ‘myth busting’ advice given.
I’ve opened far too many bottles that have clearly gone off whether to oxidisation or other factors.
There was an experiment done here;
https://scotchwhisky.com/magazine/features/18126/how-do-storage-conditions-affect-whisky/
It makes for interesting reading.
It also contradicts the ‘myth busting’.
What advice would you follow to store your favourite whiskey?
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That’s a good article but it covers a very different topic. That article is about temperature changes, while this one here was about oxidation.
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The link you posted actually confirms this article — it describes a trial of whiskey storage conditions that found storing a bottle of whiskey half-full results in small differences to flavor and 1/10 full more significant differences. If whiskey were oxidizing, the half-full bottle should have been awful, like a half-full bottle of wine stored for two years would be. Instead, the tasters found only minor differences in flavor, consistent with the lowering of proof outlined in this article.
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I think it has more to do with the vagaries of body chemistry than the infinitesimal changes that could occur in an opened bottle . If you don’t like it on your first pour , wait a few days and try again . I’ve found that a strong reaction in either direction usually indicates a new whiskey that I’m going to eventually like .
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[…] the pull of ethanol and other high-volatile aromatics out of the whisky over time, as explained here. If effective dilution of the whisky is the end result of repeated air exchange, vacuum seals would […]
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Mindboggling the people who ignore sounds logical information because of their own uneducated, ignorant gut feelings.
Great article. This is the truth about the subject. I appreciate it a lot.
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Vacuums don’t “pull” molecules out of liquids, including alcohol. I am concerned your language means you have made an erroneous conclusion about vacuums work. Unless you are highly familiar with partial pressure dependence on overall molecular pressures, you could easily be significantly wrong. Do you have a significant familiarity with partial pressure interactions, or did you perhaps go into hand-waving territory that you can’t justify?
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I know exactly what you’re talking about. But there’s no science problem here at all. You just seem deeply confused about just colloquial English. Sorry to disappoint you my friend.
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I was not confused at all by colloquial English. I am fully aware of it. I am also fully aware that people as equally confident as you will talk about why it is good to pressurize a carbonated beverage with air when the exercise is foolish. Likewise, they could believe that filling the whiskey bottle headspace with pressurized gas will stop the alcohol from evaporation. These are the things that people “know”, including those who intelligent but have simply made an invalid extension of physics. As for my being disappointed, the only things I am disappointed by was my original comment’s inclusion of the phrase “hand-waving territory that you can’t justify”. That was written in haste and expressed my concerns in a potentially-insulting manner. For that, I apologize.
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This is a very interesting article which goes into more detail than most others.
Wine is also brewed in the presence of air and has “spent most of it’s life in a porous wood barrel, with oxygen flowing in and out it daily” for years. According to this article, for wine “Any compounds that could have be oxidized should theoretically happen there already.” And yet that is demonstrably untrue. I think what this article lacks is any evidence that distinguishes the behaviour of whiskey versus wine. In the absence of such a differentiator, I’d guess whiskey should be assumed to behave similarly to wine?
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I look forward to a response to your question. I do wonder what the O2 exchange rate is through an aged barrel. Personally, I think the wine business is filled with a LOT of people who are full of crap and don’t even know it. Perhaps wine changes after you’ve opened it due to the alcohol evaporation effect as mentioned here for bourbon.
Also, I do wonder if water itself cannot pass through a wooden barrel. H2O molecules are only about 250 pm in size compared to O2 at about 150 pm. Perhaps even alcohol can pass through. Using the logic presented here in the article, the water in the bourbon or whiskey could be gone from the barrel, except for any remaining due to the hydrophilic effects of the contents. So, why doesn’t that happen if O2 should so easily pass through the oak over the course of years?
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Many wines, and most red wines, are stored in oxygen-limited conditions after the initial fermentation. This is often referred to as ‘reductive’ conditions. The CO2 produced by fermentation initially forms a blanket over the wine, protecting it from oxygen in air, and then the winemakers transfer the wine without splashing when it is racked, which limits transfer of oxygen into the wine. It is true that some oxygen enters a wine barrel, however the total amount is limited by the process of topping up wine barrels with more wine, which eliminates the barrel’s headspace, effectively displacing oxygen that has entered the barrel, as well as the storage conditions of wine barrels, which are typically cool and invariant (think ‘wine cave’), which minimizes the amount of air forced into barrels during the cooling portion of a temperature cycle. Also, it’s important to consider that wine actually improves a bit with some oxidation, which occurs in the barrel, as well as in your glass immediately after pouring. It’s only extreme oxidation that ruins a wine. So, wine is not exposed to a lot of O2 during its production, but even then some is inevitable, and even beneficial.
Whiskey production, on the other hand, does not seek to reduce contact of spirit with air. Splashing is not minimized (see dumping of barrels), barrels are not topped off, and the maturation environment is often hot and nearly unprotected from monthly and seasonal changes in temperature, which drives even more air into barrels.
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Thanks Graham, this is very informative and helpful.
By far the best resource on this topic I’ve found!
Looking a little more into wine production, it seems that they do take great care of oxygen exposure although mostly during fermentation.
So that seems to be fairly conclusive on the oxidation side of things.
Part of me wonders if some of the components of whiskey are aromatic compounds that could be affected by opening the bottle? But that would be a much smaller difference than oxidation.
I’m still confused as to why it *seems* to me that whiskey does change over time after the bottle has opened.
But that is very much an unscientific impression that I hold.
Your insights are much appreciated.
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