Gas Chromatography of Scotch?

I was wondering if anyone has ever done a gas chromatograph study of various Scotch whiskys. I've seen other food products analyzed in such a way to identify flavor components (show up as peaks, or groups of peaks), and I would be quite interested in seeing any sort of research done along these lines.

It'd make a good thesis for someone...

Dave Hinz

Reply to
Dave Hinz
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Or ruin a wonderful "thing". I remember when some fluid dynamics meisters got together and figured out why bubbles went backwards in a pint of Guinness. Not as much fun. Good malt should be like a good woman: mysterious and never fully understood.

Reply to
Jeff Folloder

Ah, but that opens up another whole avenue for arguments though, doesn't it? The bubbles aren't going down, overall, it's the cascade of beer pulling individual ones down at the boundary layer against the glass. Brownian motion - could probably work entropy and all sorts of fun stuff into it.

Well sure, but the more you know about it, the more you can go on and on about things while bluffing, and drinking. I'm not sure that's a bad thing?

Reply to
Dave Hinz

I hope you meet a lot of great engineers at the bars you frequent, Dave, because I don't think the women at the bars are going to want to talk to you about Brownian motion, entropy, and other "fun stuff". Unless of course you find an interesting female engineer type! 8^)

Reply to
DaveS

If I did, my wife would be upset, I'd think...

Reply to
Dave Hinz

Hi Dave

I have studied Scotch routinely by gas and liquid chromatography in a Tech support / spirit development / QC function.

Overall all whisky looks very similar by analysis. It is in subtle changes that all the amazingly different flavours and characters are produced. There are hundreds of identified compounds in whisky and many more as yet uncharacterised.

The largest part of the chromatographic analysis gives the congeneric profiles of the newmake spirit ie methanol, acetaldehyde, propanol, butanol, amyl alcohols.

Phenols content (peatiness) is measured by gas chromatography

Fatty acid esters are measured by gas chromatography these are significant flavour components but are a problem because of their ability to make whisky throw a haze on dilution (hence chill filtration)

Cask extractives are measured mainly by HPLC and a small number by GC.

One of the most interesting things I have seen but not personnaly tried is gas chromatography with a sniff port on the end. The flavour components are resolved by the GC and a person does the detection on the other end.

Some sulphur compounds are also analysed by GC with very specialised detection techniques. Humans are very sensitive to some sulphur compounds being able to detect them at ppb levels.

There are also other techniques used UV Vis for colour, flame AA for metals content.

The people to talk to are the SWRI Scotch Whisky Research Institute they are situated close to Heriot Watt university just outside Edinburgh.

Phil

Reply to
Phil Cousins

Sounds like fun...

I wonder if you could run that spectrum through a Fast Fourier Transform and see any interesting peaks that way? A "flavor" will be made up of several peaks, yes? By running that through a FFT, you'd distill (heh) that into a less complicated display. I don't suppose you have any raw data that you would be willing or able to share with me?

Right, which have a known peak signature, yes? By looking at the amplitude of the peaks, the relative presence of each component should be measurable. The trick is knowing how "peaty" translates into those peaks.

Ah. Different volatility then?

I wonder, is that why the local's bottle of Scapa 12 got hazy when there were only 2 pours left in the bottle? Quite disturbing to watch them pour it out, let me tell you.

I'm not familiar with hplc, is this forcing the liquid through some substrate to measure penetration of different compounds, or how does that work?

So, you can correlate the measurements with personal interpretation, or what is the point there?

Metals content? What is the origin of metals in Scotch, and do they have a noticable effect on flavor? I can't imagine it would _help_, but I've been wrong before.

Thanks, I'll google this. It seems like such a wonderful application of technology, and an enjoyable field of study. Too bad I'm a few thousand miles from Edinburgh...

Dave Hinz

Reply to
Dave Hinz

It had its ups and downs, when you do it every day...............

The overall flavour is a combination of hundreds of components and unfortunately many variations in the available analytical techniques to measure them.

Thats right. By GC under specific conditions each component has a definite retention time, the instrument is calibrated by making a standard and analysing to give response factors for each component which allows you to calculate the concentration of the component in the whisky sample.

Slightly different volatility but also present at much lower levels a couple of ppm upto maybe 30 or 40 ppm (if I remeber correctly) for very peated malts.

Probably yes, maybe some of the ethanol had evaporated (or in less reputable drinking holes the ethanol concentration may have been lowered to stretch the contents)

HPLC = High Performance Liquid Chromatography. A liquid mobile phase is forced at high pressure through a stainless steel column usually 150mm x 4.6 mm which has been packed with silica. The sample is injected onto the start of the column, the components are separated as they pass through the column and as they pass out of the column they are measured usually by UV-Vis spectrophotometry ie by passing a light through and measuring what is absorbed.

Yes thats it, notes are taken describing the observations. The notes and retention time are matched to the usual GC method and you can work out what component gives a particular smell. The retention time data can be used with another technique called GC-MS (Mass Spec) to positively identify components by "weighing them"

For example calcium present in some cutting water can cause calcium oxalate crystals to form over a period of time which you don't want so calcium levels are checked as part of the QC. Other metals are also checked as legislative requirements for safety reasons.

Your welcome! There is much research going on. Another source of information which I have found usefull is the wine makers research, they have done absolutely loads of work on cask extractives I think there is an Australian equivilent to the SWRI for wine.

Phil

Reply to
Phil Cousins

In other words, to get the "whole picture" would involve some rather complex aggregation of the data.

So, you calibrate the horizontal axis by analyzing a sample with a known signature, and then run the test sample. Makes sense; I used to work on blood gas analyzers and mass spectrometers which worked similarly.

So it _is_ a phenolic flavor. I've never tasted it as such, but never thought to think of it while tasting. Time for a test-pour (oh, darn).

I don't have to worry about them diluting it at this place, and they don't use pour spouts on anything worth drinking. Would the haze have changed the flavor, or was it strictly an appearance problem? I'm familiar with chill-haze in beer, and it sounds like this is the same mechanism at work?

So the different compounds will stop at different levels, and you measure that by absorbtion of UV? How do people discover this sort of technique? Sounds like you've got some seriously cool toys, I must say. I mean tools.

I don't suppose any of this would be information available to the public? I would think that if it could be merged with a tasting guide, that there would be commercial value to the information.

That would depend on the type of rock the water is flowing through, I suppose - but I'm ignorant of Scottish geology, I'm afraid. Is there much limestone there?

You know, some people think that analyzing something takes away from the enjoyment; I find that understanding what makes something work _adds_ to my enjoyment of that thing - I'm glad that there are people doing what you're doing. If there's any way I could see some of your results, I'd love that, but if it's proprietary information and/or otherwise not share-able, I understand completely.

Dave Hinz

Reply to
Dave Hinz

Thats it and there are still many parts of the picture waiting to be discovered. People have tried to prepare a mock up of whisky from the chemical catalogues and its not even close!

Yep !! Ardbeg 17 year old is my current favourite. The peated flavour comes from the peat reek (smoke) used when drying the malt. The peat contains tannins which combust to give various phenolic compounds eg phenol, cresols etc some people think of TCP antiseptic

There is much debate about the role of fatty acid esters in whisky flavour. they have a definite taste / odour but some think it is more of a physical mouth feel / mouth coating effect.

If you think about the esters not being water (saliva) soluble its possible they may coat your tongue and if you think about some of the flavour compounds which are not particularly water soluble they may prefer to dissolve in the fatty acid ester layer on your tongue. All those flavour compounds held close to your taste buds for an extended period! Now think about the question of do we or don't we chill filter? I have tasted a whisky before and after chill filtering and the difference is remarkable.

I think the haze in beer is a protein haze caused by soluble proteins dropping out of solution over time and with lowered temperature. There isn't any detectable protein in whisky, it doesn't distill.

Oh its almost as good as CSI!

If you place a felt tip pen dot on a piece of absorbent paper let it dry and then place a drop of water on it or maybe vodka, ink dot will split into rings of different colour. This is liquid chromatography. Now if you pulverise the paper stuff it in a tube put the ink on at the end and run the liquid through it you get the colours splitting and slowly appearing at the other end.

Most people keep the information to themselves. Its expensive to produce and there is caution about taking the mystery out of whisky. There are also possible commercial advantages to be gained.

Simple answer is I don't know the visible rocks are granite but if the water is running through the ground then who knows what it flows through.

It is true that when I taste or smell something its often a picture of a molecule that jumps into my head but I guess that just adds to my ebjoyment strangely enough!

Unfortunately I'm no longer working in the whisky industry, I do miss many aspects of it but the working hours and stress I definately do not! Now I get to taste at home not in work and some how its a little more enjoyable. I'm working in chemical analysis / synthesis at the moment.

Phil

Reply to
Phil Cousins

Well, sure. We can measure and analyze the Mona Lisa, but that doesn't mean we can make another one just like it.

Will taste for that tonight. I don't know if they have the 17, but there's a 10 or 12 which should have the same peatiness, I would think.

I know that if I ferment an ale at warmer temperatures, I get more esters. The buttery and banana and vanilla flavors, right? I've got a Scottish Ale that I like to make during summer, with the house somewhat warm.

So, there are biological interactions going on, too. Just because (a) and (b) are there, doesn't mean you'll taste both, because one might interact with the other, or with the person, to block the other, etc. Fun stuff...

Is there a list of which whiskys aren't chill filtered?

I realized that (sorry, 'realised') shortly after I posted the message.

I do love getting new toys. At work, it's servers. At home, it's anything from tools for the lathe, to the backhoe, to hand tools. I did enjoy working in Biomedical Engineering, but IT pays better, and it's more or less the same skillset.

Thanks for the reminder. My daughter (6 years old) needs a science fair experiment and we now have one.

Understood, completely. Reverse engineering being what it is..."Gee, how did they get _that_ in there" kind of questions.

When I worked in engineering on MRI scanners, I knew nuclear physicists who could visualize how the spinning proton would interact with the static and dynamic magnetic fields, through time, as an RF field hit them. One guy would literally stand up, close his eyes, and do a little "proton dance", spinning and bobbing as he visualized it. Strange duck, but he sure knew how to get good images from a spinning, dancing proton.

All this talk has been about what is in the whisky, but I assume yet more work is being done in studying _how_ it gets in there? I assume the mechanism of aging has been looked at closely? Would it be possible, for instance, to accellerate the aging process by cycling the ambient temperature of storage of the barrels at a cycle of 6 months rather than a year? I'm sure the penetration rate of whisky into barrel, both directions, has been quantified...do we know the temperature swing needed, and the time needed, for that penetration through the char layer to occur?

In other words, could we make 18 year old whisky in 9 years by storing it in a temperature-controlled environment, and making the "years" last

6 months each?

Dave Hinz

Reply to
Dave Hinz

its getting boring now. why dont you make your own little group or msn each other and leave this space for the drinkers not the analysts.

only a thought :)

Reply to
Doner Kebab

ive already got my asbestos suit at hand

Reply to
Doner Kebab

OTOH - unless my news server has broken down, there hasn't been any other discussion in this group lately. Might as well let someone get some use of the bandwidth.

chuck

Reply to
chuck

See, that's the nice thing about subject lines; they describe what's going on in a thread. We're on-topic for the group, so it's not like we're talking about auto racing or something.

Subject lines. Use them. Love them.

Reply to
Dave Hinz

"Doner Kebab" wrote in news:ypoje.15851$ snipped-for-privacy@newsfe4-win.ntli.net:

Well, I respectfully disagree. I find the discussion fascinating and completely on-topic. Could use a little judicious snipping of the older parts, but please don't stop!

Reply to
Pinko Flaggo

OK just cos Pinko Flaggo was interested...........

The buttery taste you get is (if I remember correctly) diacetyl and it really does stink of butter, you also get it in whisky but not in the cut as its so volatile. Diacetyl is usually considered an off note in most beers and again if I remember correctly is caused by fermentation at too high a temperature. The banana note is isoamyl acetate ( an ester) if you buy something that is banana flavoured this is the chemical added. In Scotch the vanilla note is due to vanillin which is a cask extractive picked up during maturation its formed by the breakdown of tannins in the wood.

I haven't seen a specific list. Anything with a strength of over about 47% by volume won't have been chill filtered because at that strength even when chilled the esters remain in solution and can't be filtered out. So generally cask strength whisky isn't chill filtered.

There is a large amount of research going on into maturation.

Temperature control is something that is being studied and certainly has an effect. But if say during a normal year the angels share is 1% what happens if you have two summers in your year?

Barrels for scotch are obtained from the Bourbon distilleries where thay can only be used once. When you put scotch in one of these fresh from America barrels its termed a first fill. First fill barrels give good colour uptake and good maturation characteristics. Now a barrel can be reused in the scotch industry so it becomes a 2nd fill, 3rd fill etc. Each time it is reused the maturation potential drops. Imagine if you took your new make spirit and filled it into 1st fill barrels and then after a year took it out and refilled it into 1st fill barrels and continued this yearly for say another 10 years what would you end up with?

You could for example open a cask, fill it full of cut up cask staves and then use that for maturation giving a huge surface area with maturation potential. I believe this is something that is done in wine maturation.

How about filtering spirit through wood chips?

The industry is goverened by the Scotch Whisky Act which says exactly what you can and can't do and most things that you might think of are not allowed.

There is also the fact that the flavour characteristics of each whisky may be down to factors which need a specific length of time or a specific combination of 1st fill, 2nd fill and 3rd fill casks

Different sorts of oak species used to make the casks can also have a huge effect European oak is different to American oak

Different sizes of casks have different surface areas therefore different maturation characteristics.

The possibilities are almost endless. I guess its important for each master blender / malt master to discover what is needed for their specific spirit and try and perfect it within the restrictions of the law.

Phil

Reply to
Phil Cousins

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