
Dilution of whisky – the molecular perspective - Tomte
https://www.nature.com/articles/s41598-017-06423-5
======
georgecmu
It's disappointing they did not reference the seminal work by the father of
the Periodic Table on ethanol/water solutions [1]. This work is often cited as
justification for why Russian vodkas are 80 proof.

1\. Mendeleev, D.I., O soedinenii spirta s vodoi, sochineniya (Total
Collection of Transactions: On the Combinations of Alcohol with Water),
Leningrad: ONTI-Khimteoret, 1937, vol. 4.

 _UPDATE on Mendeleev 's work with alcohols:_
[https://www.acs.org/content/acs/en/pressroom/newsreleases/20...](https://www.acs.org/content/acs/en/pressroom/newsreleases/2010/june/brand-
preference-may-be-in-the-drink-not-in-the-head.html)

Dale Schaefer and colleagues, who conducted the study, note that vodka has a
long-standing reputation as a colorless, tasteless solution of 40 percent pure
ethyl alcohol, or ethanol, and 60 percent pure water. All such beverages
should have the same faint or undetectable taste. But sales of premium vodka
brands have surged in recent years. Schaefer’s group at the University of
Cincinnati worked with colleagues from Moscow State University in Russia to
find an answer.

They knew that famed Russian chemist Dmitri Mendeleev, noted for work on the
Periodic Table of the Elements, made a key observation on alcohol solutions in
his 1865 doctoral dissertation. Mendeleev believed that a solution of 40
percent ethanol and 60 percent water would develop peculiar clusters of
molecules, called hydrates. That solution became the global standard for
vodka, which usually is sold as an 80-proof, or 40 percent alcohol, beverage.

~~~
timcederman
Can you give a brief explanation of the justification? I googled for the
paper, and had difficulty finding the original or citations.

~~~
jartelt
Not sure who is right, but there is this:
[https://en.wikipedia.org/wiki/Dmitri_Mendeleev#Vodka_myth](https://en.wikipedia.org/wiki/Dmitri_Mendeleev#Vodka_myth)

~~~
georgecmu
From the wikipedia page you're citing: _However, Mendeleev 's dissertation was
about alcohol concentrations over 70% and he never wrote anything about
vodka._

This is clearly not true. Page 81 (Chapter 4) of Mendeleev's dissertation [1]
starts as follows:

На осно­ваніи этого, желая съ возможною точностію опредѣлить составъ той смѣси
спирта и воды, которой при разныхъ температурахъ соотвѣтствуетъ наибольшее
сжатіе, я изслѣдовалъ смѣси, _содержащія отъ 40 до 50 процентовъ безводнаго
спирта_. Это изслѣдованіе состоитъ изъ двухъ главныхъ частей: приготовленія
смѣ­сей и опредѣленія ихъ удѣльнаго вѣса. Опишу первое, второе изложено во
второй главѣ.

[1]
[https://upload.wikimedia.org/wikipedia/commons/3/3f/%D0%9C%D...](https://upload.wikimedia.org/wikipedia/commons/3/3f/%D0%9C%D0%B5%D0%BD%D0%B4%D0%B5%D0%BB%D0%B5%D0%B5%D0%B2_%D0%94.%D0%98._%D0%A0%D0%B0%D1%81%D1%81%D1%83%D0%B6%D0%B4%D0%B5%D0%BD%D0%B8%D0%B5_%D0%BE_%D1%81%D0%BE%D0%B5%D0%B4%D0%B8%D0%BD%D0%B5%D0%BD%D0%B8%D0%B8_%D1%81%D0%BF%D0%B8%D1%80%D1%82%D0%B0_%D1%81_%D0%B2%D0%BE%D0%B4%D0%BE%D0%B9._%281865%29.pdf)

~~~
appleflaxen
where does that say whiskey? google translate provides:

    
    
        On the basis of this, wishing, with the utmost precision, to 
        determine the composition of the mixture of alcohol and water, which 
        corresponds to the greatest compression at different temperatures, I 
        used a mixture containing from 40 to 50 percent of anhydrous alcohol. 
        This study consists of two main parts: the preparation of the sms and 
        the definition of their extra vias. I'll describe the first, the 
        second is set out in the second chapter.

------
levesque
This is mostly seen from the angle of guaiacol, which is relevant for peaty
whiskies. Does this hold for less peat-forward whiskies? Could water dilution
hurt some other compounds?

~~~
tptacek
It's a good question, but much (in a lot of cases maybe most?) of the flavor
of a whiskey comes from the cask, not the mash bill, and guaiacol is a
component of the wood flavor as well.

~~~
kasey_junk
Ummm citation please? I'm not even sure of a measurement that you could cite
for "flavor" that would be generally agreeable to experts.

But certainly mash bill vs cask is the _biggest_ debate in whiskey right?

Like I'm a mash bill guy but I'll buy that I'm wrong cause the science is
unclear.

~~~
tptacek
Woodford Reserve does a rye thing where they sell a pair of identical mash
bill bottles, aged for the same amount of time, one in new oak and one in
"used" (ex-rye). The difference is huge; they're not remotely the same
whiskeys.

Meanwhile, Four Roses Single Barrel does annual releases with different
"recipes", varying in mash bill and yeast strain. If you actually go to Four
Roses, you can buy a bottle of every recipe. My brother did that and we did a
tasting, and it is very hard to tell them apart.

I can't give you a scientific cite, but from experience: cask is a huge flavor
influence. Chuck Cowdery suggests it's why indie distillers have such a hard
time turning out good product (they use smaller casks, which age whiskey
poorly).

Note though that expecting exactly this kind of response, I said "in a lot of
cases". And, of course, I'm not saying you couldn't immediately tell the
difference between a non-peated bourbon-aged barley Scotch and a corn whiskey,
or the difference between a wheated bourbon and a high-rye bourbon!

My only point is: wood flavors are important to non-peated whiskey. :)

------
skydoctor
Takeaway/tl;dr: "Overall, there is a fine balance between diluting the whisky
to taste and diluting the whisky to waste"

~~~
ams6110
I tend to drink it cask-strength, neat. I like the burn.

------
kensai
Now these are the articles I wished I read in Academia!

~~~
KGIII
Whilst still in academia, I surely wasn't interested in diluting my whiskey.

~~~
gvb
The whisky is diluted as part of the manufacturing process to the optimum(ish)
level: 80 proof / 40% ABV. You are correct to _not_ dilute it further.

Ref: _Whisky is distilled to around 70% alcohol by volume (vol-%) then diluted
to about 40 vol-%, and often drunk after further slight dilution to enhance
its taste._

~~~
tptacek
It depends very much on the whiskey! Most whiskeys are somewhere in the 40-48
ABV band (they're definitely not all diluted to exactly 40%), but "cask
strength" whiskeys go all the way up to the mid-60s (the idea of cask strength
whiskey is that you're supposed to dilute it yourself; it's sold undiluted so
that more of your money is going towards ethanol than water).

~~~
bmelton
The 2016 release of George T Stagg came out of the cask at 144 proof, or ~72%.
You might want to recalibrate your high-water mark. ;-)

~~~
anfractuosity
Wow, that's very high. I'm curious about whether the angels' share noticeably
alters the ABV, from the time the distillate is put into the cask, to when
it's bottled (as I'm assuming different evaporation rates for water &
ethanol).

Edit: [https://www.bruichladdich.com/article/the-angels-
share](https://www.bruichladdich.com/article/the-angels-share) Is quite
interesting:

"Casks stored in humid conditions lose a greater proportion of alcohol than
those stored at lower humidity levels. Conditions of low humidity draws more
water through the staves - leaving a higher proportion of alcohol in the cask.
"

~~~
bmelton
So, in the case of the aforementioned Stagg, the distillate went into the
barrels at 125 proof, and came out at 144. Clearly, the angel's share
preferred to take water over distillate.

That said, the yield was horrible -- 10-15 gallons of spirit per barrel out of
an initial barrel capacity of 55 gallons.

That said, I question whether humidity has as much to do with it as
atmospheric pressure does. The benefits of barreling something like bourbon in
a place like Kentucky is that they have 4 full seasons, and the variance in
atmospheric pressure from cold winter to hot summer creates something of a
capillary effect in the distillate -- as the weather gets hotter (and maybe
more humid) the distillate pushes into the barrels, but pulls out during the
cooler months.

Just putting the barrels in a hot place for its entire aging process _might_
accelerate the aging, or it might mean that because it loses the breathing
effect, it might extract more of the tannins and less desirable elements from
the barrels.

~~~
anfractuosity
Cheers those figures are very interesting.

Wow that's a massive loss though, I hadn't realised it could be that much
lost.

That's also interesting regarding a potential for accelerated ageing.

I'm also wondering how oxygen uptake is effected by differing levels of spirit
in the cask, I'm assuming that might effect the taste somewhat.

Edit: The thesis 'Aging of whiskey spirits in barrels of non-traditional
volume' has lots of interesting information.

"As evaporation occurs and the fill level decreases, oak not in contact with
liquid spirit dries, contracts, and becomes more porous to the entry of
outside air (28). Oxygen present in the barrel fuels oxidation reactions that
are essential in the production of mature spirits"

------
gnat
Huh, they used two different versions of the Amber software: v10 for molecular
dynamics, v15 to calculate spatial distribution functions. Amber:
[http://ambermd.org/](http://ambermd.org/) I wonder why.

~~~
Eigenstate
I use Amber to do similar calculations. It's distributed as a free set of
analysis and preparatory programs called AmberTools, which is the V15 software
cited, and a licensed simulation program, which is v10. Interestingly, that is
a super old version (usually it's released every other year or so with the
number corresponding to the year)

------
dguaraglia
I was told about this by some kind strangers at a pub while traveling in
Scotland and never looked back. It specially improves the flavoring in very
tarry/peaty whisky.

------
mirimir
So guaiacol boils at 205°C. How does it end up in the whisky, after
distillation? I mean, the water should come over before the guaiacol does.

~~~
jotux
Guaiacol is present in wood smoke. It's maybe being leached out of the charred
barrels into the whiskey during the aging process.

~~~
sxates
Right - it's the barrels that infuse a lot of the flavor.

~~~
mirimir
That makes sense. But the paper seems to claim that the guaiacol comes from
the smoked malted barley:

> Many whiskies, especially those that are made on the Scottish island of
> Isley, have a typical smoky taste that develops when malted barley is smoked
> on peat fire. Chemically, the smoky flavour is attributed to phenols, and in
> particular guaiacol, which is much more common in Scottish whiskies than in
> American or Irish ones.

~~~
levesque
I agree that this is where the smoky flavours are supposed to come from. So
your question remains unanswered. Perhaps guaiacol is generated from
intermediate compounds after distillation? From chemical reactions with the
barrel?

~~~
33W
I wasn't able to find a source in a quick search, but I wonder if
(traditionally) the charring of the barrel is also done with peat.

~~~
TylerE
No, it isn't. Scotch whisky can only be aged in barrels that have already been
used to age liquor. Conveniently, bourbon must be aged in NEW barrels, so used
bourbon barrels are the primary source used for scotch. So, the barrels are
sourced for the US and thus not charred with peat.

Other barrels used for scotch are typically fortified wine products, like
sherry or port. Occasionally limited releases will be aged in things like ex-
rum or ex-brandy casks.

------
3Pi
> on the Scottish island of Isley

The island is actually called Islay. Hopefully the rest of the article is more
accurate.

------
Semiapies
Intriguing. I always assumed it had to do with greater alcohol strengths
anesthetizing the taste buds.

------
ams6110
I've always spelled it whiskey.

~~~
NinjaViking
That's the American/Irish spelling. If it's a Scotch it's whisky.

~~~
dghf
> If it's a Scotch it's whisky.

Also Canadian, Japanese, Australian [0], English [1] and Welsh [2].

[0]
[https://www.theguardian.com/lifeandstyle/2014/apr/02/tasmani...](https://www.theguardian.com/lifeandstyle/2014/apr/02/tasmanias-
latest-export-best-whisky-world-australia)

[1] [https://www.englishwhisky.co.uk/the-
whisky](https://www.englishwhisky.co.uk/the-whisky)

[2] [http://penderyn.wales/](http://penderyn.wales/)

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sgroppino
I thought this was going to be an article by Heston Blumenthal...

