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Dilution of whisky – the molecular perspective

nature.com

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Re: Dilution of whisky – the molecular perspective

#21

Post by KGIII »

gvb wrote: post #20
KGIII wrote: post #5

Earlier quoted context omitted.

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

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.

Yup. I wouldn't want to ruin a good thing. I don't even want ice in it.

On the other hand, I've tried stuff like Everclear. That needs dilution. It's absolutely horrible, by itself.

Good whiskey needs no adulteration.

Re: Dilution of whisky – the molecular perspective

#22

Post by anfractuosity »

martingoodson wrote: post #14
mirimir wrote: post #4

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.

Liquids partially vaporise below their boiling point (eg water vapour in humid air). See http://pubs.acs.org/doi/abs/10.1021/jf60134a022?journalCode=...

Neat, that's very interesting as it does mention it's present in the ferment.

Re: Dilution of whisky – the molecular perspective

#23

Post by Kadin »

mirimir wrote: post #4

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.

Scottish (and most, although not all, other types of) whisky is produced using a "pot still" rather than a modern column, so you don't get an exact separation by boiling points. I mean, generally you're running the still at under 100C, but you get a substantial fraction of water (~30%) in the output as well.

I suspect that if you plotted the still's throughput as a function of boiling point of the inputs, what you'd get is a fairly broad normal distribution centered on the temperature of the still "head" during the distillation run, with the width of the curve dependent on the design of the still. The upper tail of that curve could easily (must, really) be catching small amounts of substances that boil at 200+C.

Re: Dilution of whisky – the molecular perspective

#24

Post by semi-extrinsic »

martingoodson wrote: post #14
mirimir wrote: post #4

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.

Liquids partially vaporise below their boiling point (eg water vapour in humid air). See http://pubs.acs.org/doi/abs/10.1021/jf60134a022?journalCode=...

There's also the possibility of forming an azeotrope (like with ethanol/water at 96% ethanol). Azeotropes are cool, they're exploited a lot e.g. as working fluids in heat pumps.

Re: Dilution of whisky – the molecular perspective

#25

Post by TylerE »

33W wrote: post #13
levesque wrote: post #12

Earlier quoted context omitted.

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?

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.

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.

Re: Dilution of whisky – the molecular perspective

#27

Post by tptacek »

gvb wrote: post #20
KGIII wrote: post #5

Earlier quoted context omitted.

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

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.

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).

Re: Dilution of whisky – the molecular perspective

#28

Post by tptacek »

levesque wrote: post #10

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?

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.

Re: Dilution of whisky – the molecular perspective

#29

Post by steveax »

jotux wrote: post #7
mirimir wrote: post #4

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.

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

I believe it is present in both the original distillate and also is leached from barrels. Some info here on the leaching from barrels:

AGING OF WHISKEY SPIRITS IN BARRELS OF NON-TRADITIONAL VOLUME

http://etd.lib.msu.edu/islandora/object/etd:1059/datastream/...

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