WWW - the Weakening Whisky WoundTable

Here's a good question, from regular reader Brendan H. which allows me to solicit the opinion of some friends...

Hey Kevin,
 
Another weird question for you, thinking as I kick a bottle of Cigar Malt.

Does the alcohol content of my whisky decrease as I near the bottom of the bottle?

I ask this because (1) there seems to be less alcohol burn as I wind through the bottle and (2) because alcohol being a light, fairly volatile liquid, could be in vapor form at the top of the bottle and released when I remove the cork.
 
If so then it might seem wise to swish the whisky around the top of the bottle to recapture any vaporous alcohol before opening.

Thanks for the science lesson.

Brendan

I responded to Brendan...

Theoretically, It COULD.
If it sits for a long time with a bad seal, the alcohol could evaporate...reducing the amount of Alcohol (by volume) in the liquid.

Once the alcohol has entered a gaseous state I don't think it will recombine with the liquid by swishing...
-Kevin

But I thought I'd ask for input from some of my industry friends...

Chris Morris, Master Distiller, Brown Forman

You are correct. Every time a bottle is opened, a drink poured out, and the bottle resealed you have created headspace. The headspace will be filled with evaporate.

Keep doing this and the ever increasing headspace will continue to sap the alcohol strength from the spirit (very small amount overall).

If you desire to return the alcohol vapor to the spirit you would have to chill the bottle to condense it. That of course is not standard storage procedure. I wouldn't worry about it.

-Chris

Dave Pickerell, Master Distiller, Maker's Mark

At the risk of being too technical ... here goes.

If the bottle is tightly sealed, only a relatively small amount of alcohol will evaporate ... and then an equilibrium condition will set up where alcohol evaporates and condenses at the same rate and the concentration of alcohol in the vapor state is constant throughout the space.... it will not stratify... The proof in the liquid will remain essentially unchanged.  Even if the bottle is opened and partially consumed, and then tightly re-sealed, this same equilibrium will be achieved, and there will be essentially no proof reduction ... even as the liquid volume decreases.  (Theoretically, there might be a minuscule proof reduction here, but I don't think you could notice it).

If the bottle is loosely closed ... or not capped at all ... The alcohol will continue to evaporate and will never reach an equilibrium because it will continue to escape from the open mouth of the bottle into the surrounding air space.  Thus, the proof will continue to drop.  This also explains why a non-chill filtered whisky bottled at a proof of 86 or greater will eventually cloud up if left for a long time with the cap off or the seal loose.  When the product reaches a proof below 86, a chill haze begins to develop, because some of the components become insoluble in alcohol and water mixtures below 86 proof ... This haze can be anything from a little cloudy to something akin to river mud.

Mark Reynier, Bruichladdich

When reducing  to obtain the desired 46% vol that we like to bottle at, it is notoriously difficult to arrive at the precise figure because the alcohol strength (in bulk) and at cask strength is so volatile. We have a legal  0.1 variance and a matter of 60 minutes is enough to reduce the strength by 01 or more.

Therefore, even at a reduced volume (a bottle) and strength -  and with exposure to air, I imagine that the strength would fall . . . albeit at a stultifyingly slow rate.

The reduced alcohol burn referred to is probably reduced by the rasping cigar smoke in the throat.

Mark

Ian Millar, Glenfiddich

First off, why would you have a bottle open so long this could happen??? THAT wouldn't happen in Scotland!

Secondly, yes - you could lose something in evaporation and the rate of loss would relate to the temperature of the room and was the bottle in direct sunlight or indeed artificial light.

(Never take a chance - store the bottle in a cool dark place, open with good friends and devour with joy).

All the best
Ian

Comments

[Kim Hoag]

What about reducing the air in the air space with a wine vacuum pump? Would you still lose alcohol?--maybe even quicker?

[Brendan]

I noticed the same change at the bottom of my bottle of Black Bush and I hadn't smoked my pipe recently. :)

By the way, this is a good time of year to buy Irish whiskey, finding a decent price by exploiting the stores' stereotypes of the Irish.

In any case, I'm grateful to Kevin and the distillers for sharing their expertise. I think that it's late enough in the morning for my Glenfiddich Gran Reserva!

Brendan

[Kevin Erskine]

I've written about using vacuum pumps in the past...to get rid of the air that could lead to oxidation.

(http://www.thescotchblog.com/2005/12/the_air_in_ther.html)

I use them sometimes, but others don't think they work well.

I do not believe that a vacuum pump is capable of pulling alcohol out of the whisky.

[Oliver Melton]

I like to store whisk(e)y in two lead-free glass decanters I have because it looks classy and allows me to better fulfill my late-18th century Lord fantasy. Needless to say, though, the "seal" on these is virtually non-existent.

From personal experience, I can say that if I leave whisk(e)y in these for too long (six months or so), the color of the liquid changes, the taste fades, and the alcohol kick (both in my mouth and in terms of inebriation) fades significantly.

Recently, I had a bottle of Balvenie DW in one and a bottle of Wild Turkey 101 in the other. The BDW faded quickly and lost 50-60% of its character in about four months. I wound up pouring it out! (The horror ... ) I think the effect on the WT was even more profound. After about a year, it lost most of its significant alcohol kick and now drinks very uncharacteristically. I poured it out yesterday.

From now on, then, I'm just going to store my spirits in the bottle in which they are sold. I've never had a problem with whisk(e)y fading in them even after leaving them for up to a year. Unless one drinks through a bottle quickly, then, avoid the decanters. There are other ways to indulge the Lord fantasy!

Read Jane Austen, buy a tweed coat with leather patches on the elbows, make friends and family genuflect when they see you, legally change your name to "Lord such-and-such," ride a horse, hate the French especially that "pretender" Napoleon, curse the loss of the "Colonies," pronounce "sked-ule" "shed-yule," ramble on about Boxing Day: the overlooked holiday, hunt foxes and/or quail in said tweed coat, marry your daughter off for a dowry, carry a walking stick, write in a Torry candidate for President in November, use "the Crown" instead of "the White House" as your preferred governmental metonym -- the list goes on and on.

Just avoid the decanters unless you want the "water of life" to become just that: h2o!