Gas in My Glass

[squire]

On another thread we were discussing the effect of cork vs screw closure in aging wine and something occurred to me.

When Bourbon is to be bottled it's first dumped (literally) from the barrel by rolling the barrels along a trough, pulling the bung, turning the barrel on its side and the contents come tumbling forth mixing with air on their way to the vat. In the vat aeration continues with water being mixed in to bring the barrel strength spirit down to bottling proof. The filling line further mixes in air with the tubes that fill the bottles.

So when a bottle is finally sealed with cork or closure a certain amount of oxygen is going to be trapped inside. As it's generally agreed oxygen is the catalyst in the aging cycle when Bourbon is in the barrel doesn't it stand to reason the trapped air in the bottle is going to further the process a bit, or that a less than perfect seal may have some effects in the long term.

[ryanc]

On another thread we were discussing the effect of cork vs screw closure in aging wine and something occurred to me.

When Bourbon is to be bottled it's first dumped (literally) from the barrel by rolling the barrels along a trough, pulling the bung, turning the barrel on its side and the contents come tumbling forth mixing with air on their way to the vat. In the vat aeration continues with water being mixed in to bring the barrel strength spirit down to bottling proof. The filling line further mixes in air with the tubes that fill the bottles.

So when a bottle is finally sealed with cork or closure a certain amount of oxygen is going to be trapped inside. As it's generally agreed oxygen is the catalyst in the aging cycle when Bourbon is in the barrel doesn't it stand to reason the trapped air in the bottle is going to further the process a bit, or that a less than perfect seal may have some effects in the long term.

Interesting...air is the mortal enemy to beer.

[smknjoe]

Great topic Squire. You are essentially asking if "bottle aging" is a reality with bourbon. I don't know, but some people certainly believe so. It would be nice to see some testing with bottles that are "fresh" vs bottles from the same batch opened 10 or 20 years later.

http://www.cooperedtot.com/search?updated-max=2013-11-11T17:31:00-05:00&max-results=6

[sailor22]

It's a small amount of air relative to the volume of liquid. Over an extended period of time there may be some effect on the Bourbon but it will probably be subtle. If the fill level of a dusty is low then there has been a bad seal from either the cork or screw top, so expect more of an effect. Some of the low fill level dusties I have tasted were really limp and almost tasteless. Always assumed that was the result of oxidation.

People at distilleries have told me that whiskey can be bruised by the rough handling on the bottling line. Not sure what that's all about.

[ryanc]

People at distilleries have told me that whiskey can be bruised by the rough handling on the bottling line. Not sure what that's all about.

[Meruck]

People at distilleries have told me that whiskey can be bruised by the rough handling on the bottling line. Not sure what that's all about.

[MauiSon]

On the other hand, despite all that air exposure and rough handling during dumping and bottling, rarely does anyone say that their private selection whiskey changed significantly between the initial selection and the bottled product. True or False?

[i believe bottle-aging can have a significant effect, air or no air.]

Edited January 1, 2014 by MauiSon

[ryanc]

Oxygen is not the mortal enamy of beer..........wives are.

[squire]

Gotta love the way these threads develop.

[black mamba]

The alcohol concentration is what makes the biggest difference between wine and spirits as far as bottle aging goes. Even port and madiera at 20% abv had enough alcohol to survive looong sea voyages from the old world to Britain and the Americas. Oxydation does have some effect on bourbon, increasing as the fill level goes lower and lower. In my experience, 12-14 months from opening is the longest I want to nurse a bottle of bourbon. After that they get "limp" or "flabby" and lose some of their zest. Of course, barrel strength bottles can last a little bit longer. Besides, all the good of aging bourbon comes from the barrel. Once in the bottle, oxydation is only a negative.

[T Comp]

Some here have been fortunate to taste straight from the barrel and then bottled as is. A small change in the proof can occur during bottling but my leaden tongue has never detected any taste change from the barrel sample. Eric/P&MLiquorsEric recently picked some 4 Roses barrels and perhaps he or others who were at that tasting can chime in if they detected a difference.

http://www.straightbourbon.com/forums/showthread.php?20064-Fun-at-Four-Roses

[Richnimrod]

Interesting stuff, kids. I'll add my 2-cents worth.

My experience is that many Bourbons experience a small enhancement after ,and a little more air is added to the bottle as the fill level decreases. I've never had a low-fill bottle long enough for the effect to turn 'negative'.

Of course, in the case of any spirit I treally do love, I'll decant into a smaller container whenever the fill-level and/or 'age' become a concern. All this is just my personal experience. Anybody agree? ... Anybody have alternate experiences?

[T Comp]

Rich, We've had numerous prior discussions on the whole concept of air time in an opened bottle and its effects...call me a skeptic. Squire's inquiry, as I understood, is about air effect even in a sealed bottle.

[GaryT]

As the surface area exposed to the air in a sealed bottle is quite small in relation to the volume in the bottle, my guess is the impact is such that it is undetectable (and any small variance could be attributed to the taster rather than the whiskey).

[B.B. Babington]

As the surface area exposed to the air in a sealed bottle is quite small in relation to the volume in the bottle, ...

[sutton]

My thoughts on this subject with some direct experience with oxygen's role in winemaking:

In wine, oxygen is slowly consumed in the bottle when it reacts with and changes the tannins and phenols to form other flavors / aromas. Other than the micro-oxygenation that occurs in the barrel during aging, oxygen is wine's enemy over the long term. Exposed to enough oxygen, wine will turn into vinegar (acetic acid) not because the ethanol is oxidized directly by the presence of oxygen, but because the ethanol content isn't high enough to kill the aerobic acetic acid bacteria that metabolize the ethanol into acetic acid.

The headspace that develops in a barrel of whiskey during aging would be deadly for wine, which is why it is always kept topped up and sulfited to act as an antioxidant and antimicrobial. Not a problem for a barrel of whiskey, which has all of that oxygen in the headspace of the barrel during its aging to form new compounds with the tannins and phenols in solution. Whiskies are also in barrels for years longer than wines (typically), so they have even more time and intentional temperature cycling to further catalyze the reactions (where wines are best aged at stable, cool cellar temps around 55 F).

So ... my guess is that after all of that time in the barrel, the overwhelming majority of the oxygenating aging reactions have already taken place. So while the dumping would most certainly introduce more oxygen into solution before bottling, the question is whether there is really anything left to react with in a substantive way. Might also be why you hear master distillers say that whiskey does not change in the bottle.

However, I will now contradict myself and say that many a bottle of whiskey seems to improve ("open up", just like a bottle of wine), when opened for a few weeks. Perhaps there are some relatively "unstable" compounds that are formed in a bottle that volatilize slowly with some additional oxygen exposure? I have seen this with very old bottles of wine - they open up when poured, have a period where they are things of beauty, and then completely fall apart after a few hours. Perhaps the same is happening in a bottle of whiskey, but the time scales are so extended it is difficult to pin down.

[TheNovaMan]

So ... my guess is that after all of that time in the barrel, the overwhelming majority of the oxygenating aging reactions have already taken place. So while the dumping would most certainly introduce more oxygen into solution before bottling, the question is whether there is really anything left to react with in a substantive way. Might also be why you hear master distillers say that whiskey does not change in the bottle.

However, I will now contradict myself and say that many a bottle of whiskey seems to improve ("open up", just like a bottle of wine), when opened for a few weeks. Perhaps there are some relatively "unstable" compounds that are formed in a bottle that volatilize slowly with some additional oxygen exposure? I have seen this with very old bottles of wine - they open up when poured, have a period where they are things of beauty, and then completely fall apart after a few hours. Perhaps the same is happening in a bottle of whiskey, but the time scales are so extended it is difficult to pin down.

Wheaters are rather well know for improving with air time, which I take as almost proof that there is still oxidation-reduction chemistry that can take place in bottled whiskey. However, a former professor of mine is adamant that there is no oxidation-reduction left to do, and he has a higher degree than I do........ but I dare say I have more bourbon drinking experience than he does, so we're even.

[sailor22]

A lot of retailers taste their samples for private selections at barrel proof but sell it after it's bottled and cut to shelf proof. The difference can be dramatic. Few retain the samples they tasted to compare against the bottled version so they have no way of knowing. If your sampling at 138 proof and the juice is going to be bottled at 90 proof expect every barrel to react differently to that much water. Plus if the samples are sent to the retailer and he cuts the big proof samples to something approximating shelf proof he will probably just use tap water, which doesn't taste the same as the water used at the distillery. A subtle but probably noticeable difference. IPlus, it's not in the retailers interest to say "this isn't nearly as good as I remember it being when I sampled it in the rick house".

When selecting at BT they used to provide two samples of every barrel at barrel strength and with enough water to lower the sample to near 40 proof. Their reasoning was that most people drank their Bourbon on the rocks and that lowered the proof to around 40. If I recall, at a recent selection there were only samples at barrel proof.

On the other hand, despite all that air exposure and rough handling during dumping and bottling, rarely does anyone say that their private selection whiskey changed significantly between the initial selection and the bottled product. True or False?

[i believe bottle-aging can have a significant effect, air or no air.]

[smokinjoe]

Wheaters are rather well know for improving with air time, which I take as almost proof that there is still oxidation-reduction chemistry that can take place in bottled whiskey. However, a former professor of mine is adamant that there is no oxidation-reduction left to do, and he has a higher degree than I do........ but I dare say I have more bourbon drinking experience than he does, so we're even.

Not to be argumentative Pete, but your professor is a brilliant man. Outside of the initial wafting off of shtuff that a freshly opened bottle may do, I join my friend Thad in the highly skeptical camp on this air time thing. As for the differentiation on this air time phenomena affecting wheated bourbons, and not rye bourbons...I'll just get in trouble if I comment further...

[mosugoji64]

I don't know if it's the air or something else in the bottling process, but I've noticed that many whiskies seem somehow compressed when they're first opened and need some time to open up. A few have been very flat initially and improved dramatically after being opened for a while. I don't know enough about the chemistry to know if it's air exposure or something else that happens during bottling, but there's definitely something going on there to me. I acknowledge that it may just be psychological and my palate might be the thing that needs some time but it has happened often enough that I lean toward the bottling process.

[squire]

I understand Brian, psychological stuff also happens when I drink.

[TheNovaMan]

Not to be argumentative Pete, but your professor is a brilliant man. Outside of the initial wafting off of shtuff that a freshly opened bottle may do, I join my friend Thad in the highly skeptical camp on this air time thing. As for the differentiation on this air time phenomena affecting wheated bourbons, and not rye bourbons...I'll just get in trouble if I comment further...

In all seriousness, he is an extremely smart man, and I'm proud to say that he was the chair of my thesis committee. Having said that, there are some things on which we don't see eye to eye, and the chemistry of bottled bourbon is one of them.

There are a few things that make the question of bottle aging a tricky one:

1. After barrel-aging, the concentration of chemicals still susceptible to redox (oxidation-reduction) or polymerization chemistry is almost certainly very small, and that makes such chemistry happen very slowly.

2. In spite of all the splashing that happens during dumping and bottling, there is relatively little oxygen in the headspace of the bottle (maybe 30-40 mL, and less than 20% of that is oxygen), and probably only a few parts per million of oxygen (15-20 ppm max?) dissolved in the bourbon at the time the bottle is sealed. Again, this makes any remaining redox chemistry very slow to occur.

3. It would be very difficult to design an experiment that would control for all variables other than aging. Any attempt at accelerating bottle aging would be suspect at best, so the only alternative would be to slow down the bottle aging in one group of samples. One possible way to achieve that might be to refrigerate or freeze some of the samples, but that's not something that normally happens to a bottle of bourbon, so that could also cast doubt on the results of any such experiment. For example, what effect would refrigeration have on the bottle's seal? To eliminate that variable, the bottles would have to have melted glass closures, but that would simultaneously eliminate a possible pathway of oxygen admittance in the aging group, so that would also be a potential problem.

It's a real pickle, and one that is not likely to be eaten and fully digested any time soon, if ever.

[squire]

I'm gonna pour some unoxidized Grand Dad and ponder these thought provoking comments.

[Quantum]

So ... my guess is that after all of that time in the barrel, the overwhelming majority of the oxygenating aging reactions have already taken place. So while the dumping would most certainly introduce more oxygen into solution before bottling, the question is whether there is really anything left to react with in a substantive way. Might also be why you hear master distillers say that whiskey does not change in the bottle.

However, I will now contradict myself and say that many a bottle of whiskey seems to improve ("open up", just like a bottle of wine), when opened for a few weeks. Perhaps there are some relatively "unstable" compounds that are formed in a bottle that volatilize slowly with some additional oxygen exposure? I have seen this with very old bottles of wine - they open up when poured, have a period where they are things of beauty, and then completely fall apart after a few hours. Perhaps the same is happening in a bottle of whiskey, but the time scales are so extended it is difficult to pin down.

I talked a scientist type about this a while back, and he offered some general ideas, but with the disclaimer that he had 0 experience in this specific area. Filtered through me, this could be completely wrong, but I fould it interesting.

According to him the dumping/mixing/bottling process would be introducing a large amount of oxygen, but any reactions would probably stop very soon after it was bottled and sealed. If I understand what he was saying, the percentage of oxygen in the air is what mattered. As the percentage of oxygen in the air drops, the reactions slow dramatically. It should reach near equilibrium shortly after the system is closed. Reactions might resume anytime fresh air is introduced, but they would stop as soon as it is the supply of fresh air is cut off.

Overall, it should be near equilibrium after several years in the barrel. The dumping/mixing process would introduce enough oxygen to finish off most of the reactions. Reactions might resume anytime the bottle is opened, but it will always be close to returning to equilibrium. Anytime it is sealed with a limited amount of air, it should return to a state very close to when it was initially bottled. All of this could vary depending on exactly what compounds are present.

When I asked what impact this would have on noticeable taste, he said tasting any of the things he works with would probably kill you, so he had no idea.

[B.B. Babington]

95% ethanol holds considerable more oxygen than water, about 25 times as much at 77 degrees Fahrenheit according to one paper. But dumped bourbon at 60% is fair bit less than that. It goes down to about 7 times more oxygen than in water at about 50% ethanol. So we might be talking 60 ppm oxygen dissolved in bourbon at 77 degrees, and higher if dump and mix done on cold days. That is enough to do stuff when ya only need to do a little bit. It is correct that there are only little bits of congeners & et cetera in the mix, but nerves in the nose (that's where we really get the drink nuance) detect very tiny amounts, so slight changes are detectable. Oxidation of aldehydes to acids can have considerable effect on flavor. And then there's issue of oxygen as catalyst for reactions.

But does it substantially change anything? Or is it a bad thing or a good thing?