The Flavour Components of Whiskey in Three Acts

Flavour Components of Whiskey. I. Distribution and Recovery of Compounds by Fractional Vacuum Distillation

Flavour Components of Whiskey. II. Aging Changes in the High-Volatility Fraction

Flavour Components of Whiskey. III. Aging Changes in the Low-Volatility Fraction

This novel experiment explores how different components of a whiskey change over time in a barrel. The novel part is how they track the components which relates to experiments I have done in the past and my own fake aging technique.

The first part of the paper details how a whiskey can be separated into different segments via fractional vacuum distillation. What they perform is quite complex to execute and certainly beyond me, but actually possible with off the shelf components as they prove. They cut a whiskey into five distinct fractions while in my own greatly simplified experiments, I cut whiskeys only in half.

What is cool about this set of papers is that it validates my intuition that the bottom half, the least volatile fraction, represents a significant portion of what barrel aging contributes. I had taken this aqueous fraction in the past and added it to other high proof spirits to synthesize aging which can be just plain fun to explore or possibly a predictive tool for a distiller. I had also cut spirits in half down the lines of volatility, manipulated the fractions independently then rejoined the two fractions which this paper somewhat validates as representative with their own organoleptic experimentation though they did control for far more variables than I did.

The second paper, which looks at the most volatile fraction is a good read which I don’t have the time to completely detail. The most notable part of it for me, which I need to learn significantly more about, is this tidbit:

In the case of wine, acetates are considered more important than ethyl esters of fatty acids for intensity and quality of aroma (van der Merwe & van Wyk, 1981). The same is likely for whiskey because of the low sensory odour threshold values of these compounds (Salo, 1970).

I can’t speak in any real depth about acetates, but I think they form through more complicated aging reactions rather than relatively easier to understand processes like acid catalyzed esterification of ethyl esters in the still.

Part three is particularly cool because to some degree you can play along easily since they are concerned with aroma compounds in the aqueous solution. They isolate their aqueous solution with a complicated fractional vacuum distillation procedure but ball park approximations can be gotten by simply putting a whiskey in a food dehydrator until the alcohol is removed.

The paper starts to get really complex and starts offering new ideas for authenticating spirits based on ratios of congeners. Page 5 of part III has some major errors in the scanning that removes part of the page but its in a section that is very technical. Eventually they isolate a few congeners (phenolic esters) they believe are crucial to mature character and then syntheticaly add them to younger spirits to organoleptically test with a tasting panel whether they increase the perception of maturity. The relationship of their contribution is not straight forward but eventually, at high concentrations, they do increase the perception of maturity.

One of the big takeaways here is how we might design educational tasting experiences for spirit tasting rooms and educational seminars. These papers validate my idea that spirits can be cut into pieces along the lines of volatility and then reconstituted in various ways. The fractions can also participate in mash-ups and when abstracted in different ways, teach us new things about perceptual thresholds which I’ve only explored in the past at the lowest level.

Also, check out the bibliographies. This team references older material I’ve never seen, possibly because they own unique collections. One of their books is a rare gem I’m now trying to acquire, bet you can’t spot it!

Six New Distillation Papers From The IRS

Unfortunately I only have these as paper copies and cannot scan them as yet.

1941 REPORT ON WHISKEY AND RUM
Valaer, Peter
J. Association of Official Agricultural Chemists (1941), Vol. 24, No. 2, pp.224-231

This paper turned out to be about a new method of determining tannin content for analysts and isn’t too important these days

1937 ACID CONTENT OF WHISKEY
Schicktanz, S.T. and Etienne, Arthur D.
J. Industrial and Engineering Chemistry (1937), Vol. 29, No. 2, pp. 157-159

This paper looks at how the pH of whisky taken by an electrode can be biased by the alcohol content and is still somewhat relevant today. This is another paper about methodologies for analysts.

1945 CARAMEL AND OTHER ARTIFICIAL COLORING MATTER IN ALCOHOLIC LIQUORS
Valaer, Peter
J. AOAC (1945), Vol. 28, No. 3, pp. 467-470

This paper was a new methodology for detecting caramel which can either be lawfully used or as an adulterant. The method was developed as a collaborative effort and was rigorously tested and commented on by numerous analysts across the country.

1956 REPORT ON METHANOL IN DISTILLED SPIRITS
Mathers, Alex P.
J. AOAC (1956), Vol. 39, No. 3, pp. 737-738

This is very brief and is just a comment on new methods for measuring methanol which is tricky due to its similar volatility to ethanol. The paper requests more trials with collaborators.

1956 LABORATORY CARBONATION OF WINE
Etienne, Arthur D. and Mathers, A. P.
J. AOAC (1956)
This interesting paper develops a means of investigating small levels of carbonation that can be left in wines categorized as still as opposed to sparking. This is important because sparkling wines were taxed at a higher rate at the time. The authors built an apparatus similar to my champagne bottle manifold and use a laboratory shaker to agitate the bottles which is similar to my hand shaking method in effect. To measure carbonation they don’t rely on a gauge but rather build a mercury manometer as a more reliable means of measuring small amounts of pressure. This is apparently why pressure can be measured in cmhg or centimeter of mercury as well as PSI or BAR.

1968 ANALYTICAL PROFILE OF CISTERN ROOM WHISKIES
Schoeneman, Robert L. and Dyer, Randolph H.
J. AOAC (1967), Vol. 51, No. 5, pp. 937-987

This extensive paper is pretty much a blockbuster and I definitely need to create a scanning. Amazing data I’ve never seen is collected from 85 whiskeys taken from 42 distilleries. No first names are given, even still, the most exciting parts are the tables that report the grain bill, fermentation process (sweet or sour mash), lactic culture added, spent beer used %, gallon / bushel beer yield, fermentation hours, details of the beer still and the doubler, the distillation proof, and the proof of entry into the barrel.

A particularly cool part are the comments from the author on previous studies of the same type and whether whiskeys then (1968) where like those of 1898 studied by Crampton & Tolman. The paper also features a spectacular bibliography with entries I’ve never seen.

The Future Is Not What It Used To Be: The IRS’ Plywood Barrel Aged Whiskey

Recently I discovered a TTB bibliography of their past scientific publications. The bibliography contained quite a few references from old un-digitized journals I’m dying to get a hold of plus a few notable IRS documents that I have no idea how to obtain. I’ve written an email to the TTB requesting information on accessing the publications and of course I’ve received no reply. These are citations I’m looking for if anyone wants to help:

1965 WHISKEY BARRELS, DISTINGUISHED CHARACTERISTICS OF NEW AND USED CHARRED OAK BARRELS Riley, C. H.
Alcohol and Tobacco tax laboratory Internal Communication, Report No. IRS-D.C.-58171

1955 A STUDY OF WHISKEY STORED FOR EIGHT YEARS IN PLYWOOD BARRELS
Schoeneman, Robert L.
Alcohol and Tobacco Tax Division Laboratory Internal Communication, IRS Publication #156

1950 A STUDY OF WHISKEY STORED FOR FOUR YEARS IN PLYWOOD BARRELS
Simonds, Paul W.
Alcohol tax Unit Internal Communication, July 25, 1950

1950 BLACKBERRY AND OTHER BERRY AND FRUIT WINES: THEIR METHODS OF
PRODUCTION AND ANALYSIS
Valaer, Peter
Alcohol Tax Unit Internal Communication, November 1950

1949 WINES OF FRANCE
Valaer, Peter
Alcohol tax Unit Internal Communication, January 15, 1949

Perhaps somebody from the right vantage point could track down the documents. Or maybe we could all file a Freedom of Information Act request together which they might take seriously and cough up the goods.

The idea of aging spirits in plywood barrels is particularly interesting and its very surprising that the IRS of all people experimented with it so long ago. A patent actually exists from 1944 for making plywood barrels.

It makes you wonder if they could use an adhesive that would make the product food safe. If it was plain pine pitch it might even contribute flavor. Was the product any good?, why don’t we see any plywood in use now? were they ahead of their time and ruthless adherence to tradition got in the way? If they bothered to do an 8 year follow up after the 4 year paper, I bet the results were drinkable.

Barrel Aging / Rhetoric / Information Design

If this is your first foray into aging, why not do it from the perspective of an exotic tax scenario?

State Board of Equalization Office Correspondence, June 7, 1954

The above link is a correspondence related to a tax case from 1954 concerning barrel aging. The heart of the issue is whether barrels are a primary ingredient in the whiskey and should not be taxed or if as a vessel for storage they are just a manufacturing aid that rubs off a little and should be taxed. A lot of money was at stake and of late this is a timely topic due to a trend in barrel aged cocktails, a recent shortage or new barrels, and the very recent exorbitant value put on ultra aged American whiskeys by the nouveau riche finance crowd. These whiskeys are often criticized for their over extraction of compounds from the barrel–too much barrel as primary ingredient.

There are many accounts of the significance of the barrel on a spirit but I singled out this paper because of its audience of non scientist law makers and emphasis on organization to support its rhetoric.  This document is trying to be persuasive to a specific audience which is something I need better mastery of.  I need to think of myself as more of an information artist like Leonard Koren whose work I return to constantly.  The author explains to an audience of laymen, who back then had better understandings of chemistry than today, the basics then in last page, switches on his lawyer attack.  He has to bring his audience up to speed quickly and succinctly for them to catch and fall for the rhetoric of his last arguments.  Rarely does common spirits writing have such purpose.

The writer of the paper, John H. Murray, wants you to see barrel aging his way and at stake is millions of dollars of tax revenue.  My own accounts of science & art do not have so much resting on their shoulders and that lack of pressure probably hinders my ability to organization and persuade.

Just recently the idea of a barrel tax has come up again in Tennessee which targeted Jack Daniels.  At the time there was no tax on barrels, which implies there hasn’t been for a long time and probably all around the country, but the county desperately needed more revenue so they tried to impose a tax in a way that would target the Jack Daniels distillery specifically.  The county ended up losing to Daniels and unfortunately the case did not produce any great organized explanations of the barrel aging process. It did however value a reasonable tax on barrels at $10/barrel or $5 million a year for Daniels.  The Jack Daniels tax was not based on any philosophical point of view of the barrel relative to the final product, but rather just the right to impose an arbitrary fee to raise badly needed money.

Over the years, countless people have asked me varied questions regarding barrel aging and it has proven a hard topic to tackle unless you want to over simplify and dodge some science. I think this paper is a great, accessible, historic look at the topic and I hope people spend some time with the source document linked above.  I’m just going to do the usual and select some quotes so they are well indexed and then chime in with some extra background information.

“For this reason, taxpayer contends that the barrels are substantially consumed in the aging process, portion of the barrels become a component of the finished product, and therefore tax should not apply on the sale to them of the barrels.” So there is no tax on the corn but there is a tax on the vessels that the corn ferments in so are the barrels they age in like the corn or like the fermentation vessels?

They reference Changes in Whiskey While Maturing by A.J. Liebmann and Bernice Scherl and “a transcript from the conference of October 22, 1947, between representatives of Association of Maryland Distillers and representatives of the State of Maryland on the subject of ‘Tax on Whiskey Barrels’.” I cannot seem to find this transcript, but maybe some better positioned readers could help out?

“When once used these containers cannot be reused for the aging of straight whiskey. They may be used, however, for the storage of wine and other uses not connected with the aging of whiskey. Whiskey will not mature properly unless the charred oak barrel is new.” What I’ve been wondering about lately is how much fixed non-volatile acidity the whiskey soaks up on each filling.  The first filling no doubt can absorb a lot but does it diminish much during the second? pH is so much more important to aging than is commonly thought.

“The alcohol molecules, being larger, do not pass through the barrel at the same rate as the water molecules. For this reason, although there is some evaporation of water and alcohol during the aging process, the water evaporates more rapidly than the alcohol and the proof tends to increase.” This I think relates to humidity and some warehouses in other parts of world can actually lose more ethanol than water.

“Certain solids extracted from the barrel contain acids and are responsible for the reddish brown color of the matured whiskey.” These acids that get absorbed are also responsible for the equilibrium between esters and fatty acids that form. Acids might have been added to faux whiskeys back in the day to synthesize the acids that would have been accumulated during time in barrel.

“During the early stages of the maturing period there is a rapid increase in total acidity. This may be due, in large part, to the extraction of materials from the barrels. Fixed acids, that is acids in the solids, increase rapidly during the first 12 months of the aging period. Liebmann and Scherl state that the entire fixed acidity normally is due to the extractions from the barrels.” Another thing I’ve been wondering after drinking quite a few bottles of the Renegade rums, which were well aged then finished in wine barrels like Madeira, is whether finishing barrels can significantly bump up the acidity of a spirit. I was lucky enough to spend a lot of time with the whole Renegade series and each had an acidic tang like no spirit I’ve ever encountered.

“The acid content is responsible for the ‘tang’ of aged whiskey.” I don’t believe many people think of aged whiskeys like Bourbon being tangy because the word sweet gets thrown around so often instead.  Imbibers these days articulate and differentiate between relative sweetness but not relative tang. What is strange on a sensory level is that the tang is an authentic gustatory sensation while the sweetness is often an illusion due to sensory convergence with olfaction where prior co-experience allows you to categorize olfaction in terms of gustation and link the separate modalities so strongly it feels like genuine synaesthesia.

“During the aging process there is a fairly steady increase in the ester content. This would indicate that the esters are probably formed chemically during that process.”  Esterification continues to happen as the pH drops because acidity is a catalyst in the reaction between free fatty acids and alcohols. Supposedly pH drops rapidly at first then levels out and continues to decrease proportional to the angel’s share changing the volume.

“During the first 3 years there is an increase in aldehydes, but after that the rate of increase levels off. That is, aldehydes are probably produced by chemical reactions during the aging process.” Aldehydes, at the moment, are a large hole in my knowledge of congeners.

“During the early months of the aging process there is a rapid increase in furfural. Newly made whiskey does not contain this substance and apparently it is extracted from the barrel since furfural is formed in the process of charring wood.” This is not the whole furfural story. Furfural is also a product of direct fire heated pot stills due to the degradation of pentoses.  Furfural ends up in the tales of the distilling run and is mostly cut away.  Esters and aldehydes and higher alcohols are commonly subdivided in analysis but furfural is something that I do not know much about its sub divisions. Is the furfural accumulated in the barrel much different than furfural accumulated in the pot still?

“Fusel oil (higher alcohols) constitutes an important component of whiskey as far as character and quality are concerned. Its content is dependent upon the method of distilling used. There is very little change in the fusel oil content during the aging period and apparently any increase is due to the increase in concentration by reason of the evaporation of water and alcohol. Some of the esters may be produced by an interaction of the various constituents of the whiskey and the fusel oil.” The majority of esters are from ethanol linking to fatty acids but esters can also be formed by higher alcohols linking to fatty acids. A few of these higher alcohol esters are considered flaws in large concentrations and are more likely to form in column stills because of the tendency for higher alcohols to accumulate in certain plates within the column which the fatty acids have to pass through. I think the banana aroma of goslings rum is due to a higher alcohol ester.

“The solids contained in whiskey are derived entirely by extraction as are the tannins. The solids apparently affect color, the tannins the acid content.” Tannin is acidic but I suspect there might also be more acids at play though I cannot name any off the top of my head.

The paper cites IRS chemist extraordinaire Peter Valaer from “the conference between the Maryland Distillers and the tax representatives of that State […]”

“During the aging process the percentages of substances other than ethyl alcohol and water increase by about five times.” Pretty high! Makes you wonder when the rhetoric starts and what side he is gong to be on! Tension building..

“The aging process, he indicates, consists of the extraction of some of the materials from the wood and the interaction of some of the acids on each other producing esters and at the same time alcohol is oxidized producing more acid. The aging process consists of a series of those changes. He is of the opinion that about one-half of the congenerics in the matured whiskey are produced by changes taking place in the barrel and the remainder are extracted from the barrel. The body of the whiskey is determined by the fusel oil content and without it the whiskey would have no character.” So here we have a summary of the opinion of the most privileged spirits chemist of the era. An astounding amount of samples from around the world came through Valaer’s IRS laboratory for analysis and he even pioneered numerous analysis techniques.  Valaer seems to paint a picture of the barrel as ingredient but then the fusel oil content, which is not a product of the barrel, contradicts it? So far it is still difficult to figure out the author’s stance.

“From the foregoing it would seem logical to draw the following conclusions:” From here I retyped the complete remainder of the paper which is more or less the last page.

“The maturing whiskey in charred oak barrels is one of the steps in the process of producing a marketable whiskey. The type of whiskey and much of its flavor is determined by the type of mash use, fermentation process, and method of distillation. Newly distilled whiskey is colorless and unpleasant in aroma and taste. The maturing process in the charred white oak barrels results in some of the higher alcohols and fatty acids being absorbed by the char eliminating some of the unpleasant characteristics that these substances would otherwise impart to the whiskey (Encyclopedia of Chemical Technology, Volume 1).” Here he paints a picture of the barrel as a filter which would be a manufacturing aid.

“The whiskey attracts from the barrel various solids and other matters which give it its characteristic reddish brown color and also extracts some furfural which may affect the body of the matured product.  The fusel oil which primarily determines the body of the whiskey is present in the whiskey from the time of distillation. Some acids are extracted from the barrel, other acids are formed in the barrel by oxidation of the alcohol and by interaction of the various substances upon each other esters are formed. These esters affect the odor of the whiskey and give it a distinct fruity odor. During the entire aging process the barrel acts as a semipermeable membrane allowing the evaporation of water and some alcohol and the introduction of oxygen into the material through its small pores. In this way the barrel and the charred interior act as a catalyst aiding in the various chemical changes which take place in the whiskey.” I feel here that he is breezing past and downplaying the importance of the compounds added by the barrel. And again fusel oil, which is not from the barrel, gets over emphasized. His stance is becoming apparent.

“It is readily apparent, therefore, that the barrel serves a distinct purpose as a manufacturing aid in the maturing of the whiskey. It acts as a container for storing whiskey during that period, its semipermeable natures makes possible the complicated series of chemical reactions which take place during the process, and the extractives from the barrel give the whiskey its characteristic color and impart to it some of its flavor. Thus, minute portions of the barrel become an important part of the finished product.” Readily apparent, what rhetoric! This again downplays the extracted compounds and their role. It also down plays their weight as a percentage of the congeners which a dissenting opinion might emphasize and requote Valaer.

“If the only purpose of maturing the whiskey in the charred oak barrel were to add to it the tannins, the furfural, the solids, and the color, the use of oak barrels would be an extremely expensive process to impart to whiskey certain chemical compounds. These compounds could undoubtedly be added mechanically much cheaper and easier. But the function of the barrel is much more important than merely imparting to the whiskey these compounds. It is used to store the whiskey and to aid in certain chemical reactions the end result of which produces a matured pleasant tasting beverage. This would seem to be the primary use of the barrels and accordingly the barrels are primarily manufacturing aids and are considered subject to tax.” Silver tongued devil!

“Perhaps we can draw an analogy to the iron balls used in the grinding of cement. During the grinding process a portion of the iron in the balls wears off and becomes a component of the cement. Iron is a necessary ingredient in the production of high quality cement. The iron balls thus contribute in two ways to the manufacture of cement (1) by grinding it to a powder and (2) by imparting to it at least a portion of the required iron content. Nevertheless, the iron balls are manufacturing aids and are considered subject to tax.” What an analogy! If I didn’t know better I’d almost be seduced myself.

“In 1948 A— D— Company sued the State Board of Equalization in Sacramento Country to recover some $X,000.000 tax on its purchases of charred oak barrels used to contain and mature its whiskey. The primary contention there made was that the barrels were sold with the matured whiskey and consequently were nonreturnable containers and exempt from tax. The court discussed the use of the charred oak barrels in the processing of the whiskey and indicated that the barrels were used for a purpose other than retention, demonstration or display and that such use was sufficient for the imposition of tax. The court did not pass on the question of whether the barrels by reason of the absorbtion by the whiskey of a portion of their content became a component part of the finished product and thus exempt from tax.” Here he discusses a related case where they try to categorize the barrels as non returnable packaging. This makes me wonder if part of being a manufacturing aid requires a higher degree of re-usability?

“Taxpayer presented a letter from the State of Maryland which indicated that the Maryland Controller had ruled that distillers could purchase new cooperage to be used for the aging and curing of bonded whiskey tax free. The basis of this ruling is not apparent from the letter.” Any legal scholars available to find more information on this Maryland case?

“It is recommended that the petition for redetermination be denied.”

If you wanted to argue it in the other direction what other evidence would you use and what other analogies would you present?

Hastie, circa 1925, and the new era of pot distillation

The Application of Chemistry to Pot Still Distillation by S.H. Hastie, O.B.E., B.Sc.

This is another newly digitized paper accessed from the Wiley Online Library.

In this paper from 1925 Hastie kicks off the systematic exploration of aroma/congener-centric pot still operation.  This work is unique because Hastie is particularly smart and presents the paper in front of very illustrious people yet somehow does not make it into bibliographies that follow.  Maynard Amerine did not reference Hastie in the 1941 Commercial Production of Brandies, Peter Valaer never referenced Hastie in any of the IRS papers, and Roseworthy Agricultural College never referenced Hastie in the decades to follow where they conducted similar work even though they were aware of Joseph Nettleton’s works.

The paper is not specifically useful to a new distiller but it does set the scene in the history of modern distillation and explains what was known and unkown at the time as well as implies how much control and consistency distillers had over their process.

What is particularly interesting to me is how advanced brewing was relative to distillation.  So much science was already applied to malting and brewing but science hadn’t even explained the effect on character of running the pot still fast or slow.  Art had produced many good rules of thumb but science had not explained them. Joseph Nettleton’s works predates Hastie’s and because of these giant gaps in knowledge that Hastie identifies, Nettleton’s tomes come across as basically just a treatise on brewing for distillers (not that that isn’t important!).  Whiskys back then were probably damn good as proven by the recently analyzed Mackinlay that once belonged to Ernest Shackleton, but they still had one foot in the dark.

From reading the commentary sections of Hastie’s other / papers, I suspect that overly strict excise rules may have strangled attempts to elaborate the ins/outs and what-ifs of pot still operation.

Hastie is very tactful and pragmatic when he lays out his plan for advancing distillation.  He carefully fragments the process so analysis can be conducted at every step of the process instead of just with the end result.  That way if something goes wrong it is actually possible to pin point the cause and correct it which he acknowledges is difficult is these stodgy, conservative operations.  I suspect a lot of the new American distilleries running on no sleep and shoe string budgets do not conduct much analysis or are even aware of what is possible. If that is the case, these new distillers will greatly benefit from brushing up on Hastie and Nettleton.  Analysis currently is so advanced and can be cross referenced against so much great data that the team led by the Scotch Whisky Research Institute was even able to identify the peat source of a hundred year old whisky sample.

Few people read the original papers so let me extract and discuss some choice quotes.  The chemistry at the end of this paper gets pretty dense and I suspect Hastie errors a bit so I will try to compare Hastie’s work to that of Roseworthy Agricultural College and even the most current explanations as best I can.

We should probably first begin at the end:

“If I should have succeeded in arousing interest in this complicated problem sufficiently to attract any additional workers to this field of investigation, then I will be more than satisfied.”

“Subsequent to the war, however, science has forced itself upon the attention of the conservative distiller, and efforts are now being made to apply laboratory control to pot still distillation.” It is strange here how the war is credited as a catalyst for advancement. More than a decade later, war is credited again as steering W.O. Graham into exploring distillation for his thesis.

“Perhaps at this time of day it is not necessary to point out that a scientist must not be expected to enter a distillery and after a few months effect fundamental changes, for nothing short of a magic wand will operate in this way, and fundamental results arrived at thus rapidly, are in the light of experience in other directions, very likely to prove misleading.” This is really interesting because so much great work was conducted at Roseworthy on pot still operation and many of its graduates entered the industry but the Australian distilling industry was barely changed.  Patience and tact might be of the utmost importance in the distilling industry.

“In a word, if we are to advance at all, the pioneer work must be carried out by technical men with scientific training in biology, chemistry and physics, with, and this is of the first importance, practical connection with and knowledge of the daily operations of the distillery.” And here we reach the limitations of any advice I can give anyone. I’ve learned a ton about distillation but I certainly have not operated a distillery and have no clue how my ideas can scale to the day to day of hundreds of gallons of this and that.  I’ve heard so many similar anecdotes from the wine industry. Lots of kids graduate from oenology school but they can’t take apart, repair and fix the pumps that move the wine around.

“This state of affairs resulted from a very superficial knowledge of a very complex and conservative rule-of-thumb series of processes, of the precise workings of which the general information was, and still is, very meagre.” Hastie starts to make his case for science and analysis by examining what happens when a certain amount of grain produces a less than expected yield.  Previously it was pass the buck and the blame game and distillery operations were not well fragmented or systematized to identify where the problem started.

“Considered as a rule-of-thumb process without guarantees of yield, the process is very simple, but considered as a problem in the production of full yields of a definitely uniform product the subject bristles with difficulties of the most complex kind.” Cooking is slowly being elaborated in a similar way these days with the advent of temperature controlled cooking and baking scale style recipes popularized by Modernist Cuisine. I’ve talked about this in the past with classic cocktails where recipes go from dynamic towards static.

“Quality and character are the prime essentials of the business, and all that I may say as to the value of control is to be taken subject to the proviso that this control is of economic value, and where it has affected existing character it has improved it, and has certainly not proved detrimental.” This relates to my notion of involvement.  I think people thought character was the product of a lot of chaos and mystery. Things were made with a low degree of involvement so the magic could happen by itself.  Being too conscientious risked stripping the magic away. If something could be more efficient, bureaucratics would push it that way to a point which compromised character. But this was a lot of short sighted thinking.  Control and systematic study could help eliminate flaws, regrets, missed opportunities and ordinary aroma thus cultivating extraordinary, singular character, terroir.

Hastie goes on to subdivide the production of distilling material into malting, mashing, and fermentation where maximum theoretical yields are calculated for each segment to isolate problems. “We thus ascend from art to science.”

Hastie starts to explain the analysis of the fragmented processes which I think was well adopted by brewers but not yet by distillers. Examine barley and determine starch percentage and germinative capacity. Assess nitrogen percentage. Kiln barley to assess moisture content using a moisture standard of 3 per cent for extract obtained. Grist is evaluated because malt is subject to change with storage. During fermentation gravity is examined to be compared against gravities for ferementation completion.

Control of the yeast supplies is where things get really interesting to me.

“Hitherto the scientific care of yeast both as to storage and control in pot still distillery work simply has not existed.”

Previously I had no idea how distillers were getting their yeast. I thought they must have proprietary supplies not related to beer brewing.  I suspect American whisky producers had all the same practices though I’ve never read anything to confirm it.

“As soon as the brewer has finished skimming and pressing, the yeast surplus is dumped into the general sump which is the distiller’s source of supply, from there it is forwarded (in casks or pressed in sacks) by rail and to the Western Isles by cargo steamer. It is frequently on deck in the heat of the sun, uncovered, it is collected at leisure and stored in the distillery yard regardless of temperature or anything else, and is finally drained off in buckets through a cock in the cask, the mouth of which is filthy as a rule with dried yeast, etc., from previous buckets. It is then tipped into the wash back to ferment the wort and is by this time a mixture of doubtful cleanliness, of very uncertain vitality, and certainly always a seething mass of organisms of every description. Truly a picture black enough to make Pasteur, the scientific father of our allied industries turn in his grave.” Wow, very surprising.

“There is no doubt that the yeast used is frequently blamed for defective fermentation, when the wort is the real determining factor, and so long as worts are prepared, may I say scientifically, blindfold, the distiller cannot definitely say whether the yeast or the wort is the cause of unsatisfactory results, but by controlling each of these factors he may strengthen his position enormously when complaints have to be made to the provider of his yeast.” I think that these days the yeast companies are so good that we almost do not have yeast problems.

“In the application of the system, graphs are plotted of efficiency coefficients which are kept throughout the season, and afford immediate comparisons of various distillery productions in all departments of process on a basis strictly comparable, and independent of the nature or quality of the barley employed. Distillers are prone to compare the produce of different distilleries, although the materials may vary so much that such a comparison is unfair to the operative distiller and quite worthless.”

“…control is the desirable jumping off point and must precede research. Control must come first and be complete and research must follow as the outcome of control.” I wonder how Hastie would feel about new distilleries. Do they have enough control and involvement to justify new explorations and attempts to be differentiated in the market place.  Can organoleptic analysis via tasting panels be counted on for control?

And now we to Hastie’s research ideas some of which are really interesting:

“The mashing process. The question of extra yield.”

“there is the question of treatment of mash and mashing water with inorganic salts. Nettleton in his book on distilling states that 20-40 grains per gallon on salts such as NaCl or CaCl2 will enhance the diastic power and increase the amount of protein matter dissolved in mashing.” Hastie goes on a little more and I am definitely in territory I know very little about. I’ve learned quite a bit about operating a still, and of fruit based wine making but I know comparatively little about brewing.  I was under the impression that NaCl seriously inhibited yeasts but it would be interesting to see how these amounts translate to g/L and therefore how much of an interesting water source could be used such as ocean water to also add organic material as well.

“From further work carried out on this question and not recorded here, as being still in progress, the opinion has been formed that the hydrogen ion concentration of the mash water and mash materials was the real factor operating in these experiments and in those of Nettleton, as adjustments of the Hydrogen ion concentrations of the water taking into account the mashing materials has a greater and more definite effect upon the yields than the addition of salts alone, and further the effect of these additions is found to be largely due to their influence upon the pH of the mash, and is, in fact, an inefficient “trial and error” method of adjusting the pH. The adjustment of the pH of pot still distillery mashes and worts is of the utmost importance to distillers and is at present the subject of investigation, but it is regretted that further details cannot be set down here meantime.” Super interesting! What I think they are arriving at here is the sour mash process.  The pH is adjusted not just for microbiological stability but also for yield, and from other papers I suspect as a catalyst for esterification in the still. I was under the impression that Scotch whisky distillers did not exactly sour mash but that might not be the case or maybe they just adjust it by different means.  What is also interesting is about the same time in Australia, Alan Hickinbotham of Roseworthy Agricultural College was revealing the significance of pH to the stability of wines.  Prior, something like 20% of wines were sent to distilleries because they were essentially spoiled but after acid additions were made to adjust pH, that number went down to 3% and still wine product increased very significantly.

“It must be remembered, however that the success of the treatment of the mash is determined not by the water composition alone, although this is of importance, but to a much greater extent by the pH of the mash as influenced by the malt used.”

Hastie acknowledges skipping fermentation in the paper because he wants to focus on the operation of the pot still.

“When a definite scientific method of control has been arrived at, then attention may be turned to the origin of the substances stamping the character on spirit, but so long as the distiller is in the dark as to the precise effect of varying the distillation process with a given fermented wash, it is premature to enquire into the origin of the character producing impurities in the wash.” Hastie starts to propose working backwards.

“That is to say, we must deal with the second and final distillation first, wherein separation and interaction of substances takes place,  before we are in a position to deal with the primary distillation where separation and interaction of substances also takes place, but where in addition new substances are actually produced not previously present in the wash.” Hastie sees the second distillation simpler than the first. A lot of magic happens in the first distillation and it is probably not fair to relegate it to a “stripping run”.

“In this way the control of the selection of the different desirable materials from the wash, and the exclusion of the undesirable, must be definitely settled, and then the origin and nature of the substances can be tackled.”

“To digress for a moment in explanation of what follows, it appears to be the case that after the Royal Commission on whisky had given its findings the tendency was to attempt to eliminate partially or wholly many of those impurities from pot still whisky which constitute its commercial asset and as the amounts and nature of these impurities are of first importance, the endeavour of the distiller is now to attempt to retain definite proportions of them in his whisky where such is already in active demand, or to attempt to incorporate the desirable and eliminate the undesirable, where the existing demand for his particular product is small.” I wonder if the popular press created a demand for lighter spirits once they had namable compounds to write about and falsely implicate in hangovers. David Wondrich could probably give us some nice background on this idea. Hastie goes on to say that whiskys with undesirable character could be stripped of it and used for blending with other whisky of more desirable character.

About congeners: “They are doubtless largely derived from the peats used in drying the malt and also found in the water which in the large majority of cases (in Highland whiskies) drains through peaty soil.” This paper pre-dates Hastie’s other paper where he spends more time on water.

“We will therefore start with the product of the first distillation that is, the low wines which in practice is normally collected and mixed with the foreshot and feints, that is, the first and last runnings from the second and final distillation of the previous period.” Here we see acknowledgement of the recycling of fractions.  The Roseworthy papers explain a lot about recycling because it was not common practice in Australia despite being integral to Cognac production. It is also super important to realize that whisky is the product of interlocking batches.

Hastie presents a chart that gives some numbers for the composition of low wines + feints + foreshots (volatile acids, esters, higher alcohols, aldehydes, furfural).

“[…] in addition to which a small proportion of other very important character giving bodies are present of which practically nothing definite is known beyond their undoubted existence, […]” He realizes due to analysis constraints he is not working with a complete picture.

“The function of the second distillation therefore is to select primarily, in the whisky or second fraction an alcoholic distillate containing the above, and to exclude from this fraction by collection in the foreshot and feints and rejection via the spent lees, the undesired balance of impurities.”

Hastie presents more great data sets. One particularly cool data set looks at the second distillation (only via laboratory still) and shows the accumulation or trailing off of every major congener class over the course of 19 fractions. We should probably compare Hastie’s data against the brilliant charts of Robert Léauté’s 1989 James Guymon Lecture.

“[…] general uncertainty of the distillation as a process of separation.” All these things are being thrown at you at different rates and you have to catch them. There are lots of moving parts.

Hastie presents another data set of 80 fractions taken at 15 minute intervals from an actual spirit run in the distillery. The previous data set was only from a laboratory setup.  Getting real world data is a remarkable feat back then because of excise restrictions on sampling. Esters do some very erratic things in his data set.  He notes that laboratory results and real world results differ.

“One of the obvious methods in practice by which a given character may be altered always presupposing a definite low wines and feints and foreshot mixture is by collecting less foreshot or more foreshot, less feints or more feints, etc.”

Hastie spends some time explaining what happens when you enlarge or contract the cuts but then notes that those options are obviously limited and other methods need to be sought out for modifying character (changing starting proofs by altering recycling, altering time under heat, altering lyne arm to effect subtle reflux rate).

“One can readily understand that any factor tending to greater or less rectifying effect of the apparatus will at once alter the character. Such factors are increasing the height or diameter of the still neck, and inclining the lyne arm; and the use of plant designed to partially condense the spirit and so return a proportion to the still will have similar effect.” The very last part here I think refers to what is sometimes called a brandy ball. It isn’t exactly a reflux column but rather just a simple way to add more reflux to a pot still. Usage was described in the Roseworthy papers but I haven’t seen one described anywhere else don’t think any producers currently use them.

“The speed at which the distillate is driven off from the still will also have its mechanical effect on the product. As an instance of the effect of one of these factors a few tests of runs of laboratory still using the types of head and lyne arm detailed are given to show clearly how one of the variable impurities of the character producing substances, namely acid, actually reaching the whisky is varied with different apparatus.” The speed has a two-fold effect. Firstly changing the time under heat, by changing the speed, varies congeners creation in the still and secondly increasing the speed challenges the natural reflux of the still head.  Explanations for these phenomenons where hard to come across but were explored in the Roseworthy projects. A pot still has more reflux options than you’d think and besides the rate of distillation, changes to the lyne arm such as angle or length can change alcohol content of distillate and thus congener distribution markedly and this was again explored in simple experiments at Roseworthy. Hastie provides drawings of different laboratory lyne arm options and shows a chart that illustrates how each option varies in volatile acids collected. I think his chart could be set up better.  The options with the least amount of reflux collect the most volatile fatty acids.  The volatility of these fatty acids, it must be remembered, is a function of both their boiling point and relative miscibility in water/ethanol so when reflux is varied, and thus alcohol content of the distillate varied, this relative miscibility becomes a big factor in explaining volatility.  My favorite better explanation of the subject comes from Amerine’s Commercial Production of Brandies.

“[…] as the impurities tending to come over in the distillate vary with the alcoholic strength of the vapour some tending to remain in the still at the higher strengths, and others tending to pass over, consequently more or less rectification will mean corresponding differences in the amounts of the different impurities actually passing into the distillate.”

“Schridrowitz (loc. cit.) pointed out that the simple distillation of low wines, etc., gave rise to changes in the amounts of the constituents in spirit with elimination of impurities via the spent lees.” Distillation on the lees was also explored at Roseworthy because it was common practice in Cognac but not Australia. It may seem counter intuitive that distillation on lees could reduce impurities such as aldehydes.

“The process of distillation of the low wines, and feints in the spirit distill is essentially a process of hydrolysis of the esters giving acids and water of oxidation of the alcohol to aldehyde, of production of esters from alcohol in presence of acid, oxidation of alcohol to acetic acid, and many other subsidiary actions no doubt.” Hastie sets out to tackle the reactions taking place in the still.  I am well acquainted with the esterification reaction but the hydrolysis reaction where esters split apart is somewhat new to me, but explained particularly well by Peter Atkins in his book on chemistry, Reactions.  Hastie seems to think the splitting apart of esters is more common than the formation of esters in the still, but I’m pretty sure he is incorrect.

“Apparently the distillation in the normal courses in practice increases the acids at the expense of the esters and decreases the esters, due to the interaction taking place between an alcohol and acid mixture in presence of esters and water. When the low wines + feints + foreshot are subjected to hydrolysis under a reflux condenser a similar effect is observed on the total acids and esters. Further when hydrolysis for one hour is followed by distillation the cumulative effect is a smaller increase in the total acids and a smaller decrease in the total esters in the fractions.” One thing to note here is that I’m pretty sure Hastie is dealing with the second distillation where there is no non-volatile acids to catalyze esterification.  So maybe esters are predominantly formed in the first distillation then unravel to a small degree during the second distillation then even reform post distillation as everything reaches an equilibrium.  Non-volatile acids absorbed from the barrel, it should be remembered, will influence this equilibrium. The refluxing Hastie mentions has the effect of pushing the solution towards equilibrium but distillation is not at equilibrium because the alcohol water concentrations are always changing as vapor leaves the distill.  The French also note that best results of double distillation are achieved if the second distillation happens quickly before the low wines can sit around and approach equilibrium.

“In these tests and in those which follow, the total amount of esters destroyed does not agree with the total amount of additional acid found, except in those cases to be given in detail below where alkali was added to the liquid before hydrolysis and distillation, the use of alkali limiting the number of possible reactions and allowing of more definite conclusions.” I don’t completely know how to interpret this. The only thing I can think of is that when ethyl acid is broken up it could become plain acetic acid or acetaldehyde. I can’t remember the names of the processes for aldehyde formation.

“This is probably a case of the reversible reaction known to occur between acids + alcohol and esters + water. The acid and alcohol heated together, yield esters up to the equilibrium point dependent upon the conditions of temperature and relative quantities of alcohol and acid present.” I think something he is missing is pH influence from other non-volatile acids. this comes into play during the first distillation where significant non-volatile acids are present and then again in the barrel where pH drops due to the accumulation of new non-volatile acids.

“[…] and although an equilibrium point should be reached theoretically after a definite amount of hydrolysis, this equilibrium point will never be actually attained in distillation as the total esters and alcohol vary in amount as distillation proceeds, and products pass to the distillate.”

Hastie goes on to explore distilling a low wines + feints + foreshots mixture in the presence of sodium hydroxide (lye) to see what happens. He determines that the formation of esters and the splitting apart happens simultaneously in the still.

“When the conditions are, as in practice, those of distillation, the hydrolysis of esters will occur, and the production of esters will also take place, but an equilibrium point will not in fact be reached, owing to the removal of varying amounts of the interacting substances to the distillate.” This lack of equilibrium is why new make spirits can change so markedly in the first few months.

One thing that definitely needs to be noted is that Hastie is only looking at the second distillation of double distillation. The first distillation is very different because of all the non-volatile material that influences pH and thus equilibrium and also possibly provides a fixative effect reducing the volatility of certain compounds.

from the discussion section worth noting:

“He did not agree with the suggestion that character might be determined by local bacterial conditions, so far as to account for differing whisky characteristics in the distilleries in a district.”

 

Mackinlay Scotch: The closest to invincible any whisky ever got

Sensory and Chemical Analysis of ‘Shackleton’s’ Mackinlay Scotch Whisky from the Journal of the Institute of Brewing.

The closest to invincible any man ever got is the tag line commonly attached to Tom Crean who was Shackleton’s second officer on the Endurance.  Many people I’m sure have come across numerous short articles that mention the discovery of some of Shackleton’s whisky in Antarctica or the replica that this chemical analysis inspired, but few probably have come across the original research paper on the analysis.

The paper is particularly cool and not too hard to follow.  After the last two posts about Hastie’s 1920’s inquiries into pot distillation in Scotland, it might be interesting to take a look the same era but under modern analysis.

*Their analysis looks at process related congeners (operation of the pot still), fermentation related congeners (what went into the making the beer), and a look for markers that could indicate under what circumstances the whisky was aged.

“While Scotch malt whisky at the end of the 19th century was generally regarded as heavily peated and harsh in character, Charles Mackinlay & Co. Distillers were producing a malt whisky with an altogether more subtle character at their Glen Mhor distillery near Iverness. The sensory and chemical analysis of this unique whisky artefact significantly changes our understanding of the quality and character of Scotch malt whisky produced by our distilling forefathers.”

I suspect the fact that the Mackinlay whisky turns out to be really modern is what made it possible to make a replica from stocks produced in the modern era.

*They passed a sample of the whisky through a tiny filter for microbiological analysis. I guess that would tell them if any bacteria was able to grow in the bottle and impact aroma.

*They figure out the freezing point of the whisky which I suspect can explain what state, solid or liquid, the whisky has been in for the last 100 years.

*They measure alcohol strength, colour, transmittance (?), pH, and acidity (total acidity?)

*The samples get radiocarbon analysis to help rule out fraud.

*Multiple types of chromatography as well as mass spectroscopy were used to analyze all major volatile congeners.

*15 members of the Scotch Whisky Research Institutes expert tasting panel performed organoleptic descriptive analysis.

*The low freezing point and the placement below the flour of the hut may have buffered the whisky against large temperature fluctuations and prevented damage to the glass bottles.

*No evidence of microbial contamination.

*Alcoholic strength was 47.19 “and given the retention of the cork closure integrity and the apparent annealing of the cork to the glass, this may represent the actual bottling strength.” No strength was printed on the label which was not required until 1907. pH 4.3 and “no apparent loss of teh 700 mL fill volume of liquid, this initial spirit analysis data suggested the the whisky had no deteriorated during its storage in ice.”

“The flavour profiles for the three samples are shown in Fig. 4. All three samples were similar, exhibiting a balance of peaty, mature woody, sweet, dried fruit and spicy aromas. The peat levels did not dominate, while the mature flavours were consistent with maturation in sherry or wine casks. Low levels of both fresh fruit and green/grassy characteristics, and immature aromas such as feinty and sulphury were present. With no off-notes, the whisky did not exhibit any aromas not found in modern whisky.”

*Congener analysis created “fingerprint” for the whisky that didn’t different with what is currently expected from modern whiskys.

*summed concentration of amyl alcohols was at the low end of what is expected from Scotch malt whisky.

*furfural was in the middle of the expected range which indicates it was malt whisky and not blended down with grain whisky which would have a lower furfural concentration.

“The major volatile congener data suggested that the ‘Mackinlay’ was a malt whisky, rather than one blended with grain whisky.”

shackleton spider “At low temperatures, the long chain ethyl esters in malt whisky may precipitate and form a haze that clouds the liquid. To prevent haze formation in bottled whisky products chill filtration was introduced during the 1960’s, so it was surprising that haze obscuration was not foundin the Mackinlay whisky after its many years at low temperature. However, the choice of a high bottling strength (47.19% abv) together with low concentrations of the ethyl esters of lauric, palmitic and palmitoleic acids […], put the whisky at only a very slight risk of mild precipitation.”

*They were able to do analysis on phenols which can determine peating levels and even the likely origin of the peat. The amounts put the scotch in range of “lightly-peated” whisky currently produced supporting the sensory findings.

“The burning of peat imparts distinct flavours to malted barely during kilning, and these are transferred to the new make malt spirit on distillation. To identify the source of the peat used in the production of the Mackinlay whisky, the concentration of peat-derived phenols were compared, using principal components analysis (Fig. 5), with samples both of new make spirit and of matured Scotch malt whisky whose peat origin is known, as the impact of maturation on peat derived congeners is not fully understood. Figure 5 shows that the Mackinlay whisky is very similar to whisky currently produced using Orkney peat, confirming the historical records that peat was sourced from the Isle of Eday.”

Wow!

*They are able to tackle how it was barreled just like the peat.

*Lactone ratios help support the evidence that the whisky was aged in American oak and not European.

*Concentrations of Tyrosol, “a constituent of non-distilled beverages such as sherry or wine was also identified by HPLC” […] “for a selection of ‘first-fill’ sherry cask matured Scotch malt whiskies”. So I guess they used first fill sherry casks.

*Concentrations of potassium were also in line with “first fill sherry casks rather than a re-filled sherry cask or bourbon cask, which were not in common use until the 1930’s.”

“This analysis, that relates a range of compounds to the maturation period, the cask type and the previous use of the cask, indicates that the Mackinlay new make spirit was matured in a first-fill American oak sherry or wine cask for a period of greater than five years. The sensory analysis supports this hypothesis with the whisky exhibiting the woody, sweet, dried fruit and spicy aromas typically associated with sherry cask maturation.”

*They found maturation congener 5-hydroxymethyl furfural (5-HMF) with is associated with sherry casks for wines such as Amontillado and Oloroso.

“It should be noted however that 5-HMF, as well as being a component of heat-treated or toasted casks, is also a component of burnt sugar and/or caramel. We have no reason to believe the amber tint of the whisky was not wholly cask-derived, but one cannot rule out addition of a burnt-sugar or caramel-type tint product to colour the whisky at bottling as these were available at the time.”

So there was no sugar.

“The presence of short chain acids characteristic of feints (butanoic, 2-methyl and 3-methylbutanoic acids), suggest that the cut point from the spirit to feints during distillation was made at lower alcoholic strength than that commonly used in current pot still spirit production. This later cut to feints increased the intensity of cereal popcorn aroma” […] ” and that of earthy/mouldly leaf aromas”

*Now they get into ethyl carbamate which is something new to me.  This congener is considered carcinogenic and I’ve come across papers recently that describe it as a regulated compound and show efforts to reduce it in spirits.  The levels they found were consistent with low levels currently found in modern Scotch production.

*They mention older barely varieties in use at the time what had more ethyl carbamate precursors. I guess varieties were changed to reduce this congener.

“Given that the level of the ethyl carbamate precursor, epiheterodendrin, may have been relatively high in the older barley varieties used during the late 1900s [typo?], the low concentration of ethyl carbamate reported here suggests that the distillation in the copper wash still was carefully controlled to prevent frothing of the wash and fouling of the copper spirit still.”

I don’t really know how to interpret this quote. So they are careful and avoid puking of non-volatiles during the first distillation and that is really enough to cut down on ethyl carbamate?

*They mention another compound, NDMA which is produced during kilning, that is surprisingly low, given that efforts were not made to reduce it until the 1980’s.

“The levels of process-related compounds, such as ethyl carbamate and NDMA and the metal and cation/anion content, are consistent with those currently found in malt whisky, and give us an insight into a controlled production process. The results presented here significantly change our perception of the quality and character of Scotch malt whisky produced over 100 years ago.”

Simply amazing. It is astounding what modern analysis is capable of telling us about such a spirit sample.  A brilliant work.

One bibliography entry jumps out at me as being really interesting but I cannot seem to find it:

3. Clutton, D. and Simpson, A., The shelf life of spirits. In: Elaboration et Connaissance des Spiritueux: Recherche de la Qualite Traditoin et Innovation R. Cantagrel, ed. Lavoisier-Tec & Doc: Paris, 1992, pp. 548-556.

From Free Fatty Acids to Aromatic Esters: Esterification in the Still Made Simple(r)

[More important than esters is the mysterious congener class often referred to as rum or Cognac oil and I have unraveled its mysteries in other more recent posts. Decisions made to maximize rum oil will also maximize noble esters. Esters can be faked in contrived ways while rum oil is still divine (though that may change).

Please feel free to comment and tell me I’m wrong or ask me to clarify anything. This post will probably be edited frequently and many of the comments will precede the edits.

This is an excerpt from the book on distillation I’ve been working on forever now. I’m trying to re-frame the text in a way that explores and emphasizes three main concepts:

1. Distillation is simple or fractional. Simple distillation is the separation of the volatile from the non-volatile while fractional distillation involves the further subdividing of the volatile.

2. Distillation is non-equilbrium like a pot still or can approach equilibrium such as in a column still. Volatility is effected by more than boiling point and the relative miscibility of a substance in water or ethanol can make something with a boiling point higher than water extremely volatile.

3. Aromas are either created in the still or not depending on the presence of aroma precursors. Many fractions are recycled not only to salvage alcohol but also to allow more time under heat to turn aroma precursors into aroma compounds.

One of my goals was to give an introduction to the topic and some general advice for distillers of low levels of involvement. Many of the ideas are speculative. I was hoping to shed light on the science just below the surface of many distilling rules of thumb.

It is a complicated topic full of tangents but I kept it down to 2100 words!

***

Many of the most revered aroma compounds are born in the still. Under certain conditions with the right precursors to feed the various processes, significant amounts of new aroma compounds are formed. The main process of aroma creation is esterification where free fatty acids react with alcohols under heat to form esters. Esters are very volatile and their fatty acids precursors are also volatile, even though they have boiling points higher than water. Many fractions of the distillation process are recycled into subsequent runs to give more opportunity for esterification. The recycling phenomenon means that you cannot just produce one batch of product because the final distillate is actually the product of many integrated batches. Aroma creation is not always maximized and restraint is often practiced to produce an elegant spirit. Pot stills are highly regarded for their ability to create new aroma compounds but if column stills are operated with certain methods of recycling fractions, they can also produce very full flavored high ester spirits.

Many processes are responsible for aroma creation but likely the only process that can be controlled to any significant degree during still operation is esterification. Other processes like maillard reactions, hydrolysis and oxidation are definitely important but when it comes to handling the still, they are likely just byproducts of decisions made regarding esterification [there are minor problems with this claim]. Full flavored spirits in pot stills differ from column stills by how the byproduct processes happen [I’m slowly learning the chemical ins and outs of articulating this]. If a pot still and column still were operated in such a way as to end up with the same ester content they would differ greatly in compounds created by other minor processes and the pot distilled product would likely be regarded as more complex.

To get esters to form in the still, the distilling material needs free fatty acids as precursors. Some source material is higher in fatty acids than others and some fatty acids are more noble than others. For example, apple varieties differ by fatty acid content with the higher being better suited for distilling material. The same is true of grapes. Not all esters are formed in the still or during fermentation. Esters are often already present in the source material and typically the higher the better. In fruit, esters form by enzymatic processes during ripening, more form by fermentation, even more form in the still, and believe it or not, even more form in the barrel. High total acidity in the source material often correlates to both high ester contents and high fatty acid contents which is why the wines of Cognac can yield a product with a higher ester content than the acid deficient wines used for California brandies. [What I’m missing here is that at the same time esters are forming they are also breaking up due to hydrolysis but at a different rate, often they even reform. The first distillation, due to its significant total acidity, may be characterized by a positive net ester formation while the second distillation which has no significant non-volatile total acidity (to catalyze esterification) is characterized by a net loss of esters. What I need is better research papers to support this. Most research projects only look at the first distillation and none (known to me) compare and contrast the processes at work in each distillation of double distillation.]

Yeasts are big sources of fatty acids and a percentage of the lees are retained in distilling material to produce esters from those fatty acids. Most full flavored spirits do not incorporate all of the lees due to off aromas produced as a result of having too many solids in the still. If there are too many solids there is a tendency for scorching. The relatively ordinary aromas produced from the lees may also overshadow the singularity and terroir of the source material. Some traditions exist of making brandies from accumulated amounts of left over lees but these distillers likely have stills designs to handle high concentrations of solids such as the steam jacketed stills used for grappa production or “rousers” which continuously stir the distilling material. [A big thing this misses is how distillation on the lees traps certain non-desirable congeners possibly through a fixative effect of reducing their volatility.]

High total acidity in distilling material may be important to catalyze esterification during the first distillation phase of double distillation in a pot still. There are many approaches to having a high total acidity as seen in high ester spirits like Cognac, Bourbon, and Jamaican rum. The wines used for Cognac are naturally high in total acidity which might be why Cognac distillers have always favored slow double distillation in a pot still as opposed to a column still. California brandies may have opted for a column still because they never had enough total acidity to justify the extra time and fuel expense of a pot still.

Distillers of Bourbon increase the total acidity of their distilling material with the sour mash process where a portion of the non-volatile fraction of the first distillation phase, often called backset, is recycled into the next fermentation. The sour mash process has the three fold effect of increasing micro-biological stability, recycling fatty acids, and inducing acid-catalyzed esterification in the still.

The use of dunder to make high ester Jamaican rums is very similar to the sour mash process. Dunder is the non-volatile fraction of a sugar cane fermentation after distillation and characterized by high acidity. Molasses is so concentrated a sugar source that significant amounts of dunder can be used to bring the sugar content down to a reasonable level. Dunder can represent as much as 50% of a molasses based wash for a high ester style of rum. Sugar cane is deficient in acids so Dunder is further acidified with sulphuric acid. The high total acidity creates slow, inefficient fermentations where secondary bacteria produce numerous extra aroma compounds [I have recently learned many of the finer points of this and attached the evolution of dunder’s use to some first name and specific dates). In the 19th century, high ester styles of Jamaican rum were produced as concentrates for exportation which would be diluted with relatively neutral spirits before bottling. The distilling material used for high ester Jamaican rums may have had 2.5 times the total acidity of the wines used for Cognac. Such high acidity would likely shorten the lifespan of a copper boiler but it is unknown (to me) whether Jamaican distillers used copper or wooden boilers [wooden boilers and I’ve found more specifics on that!].

Another idea for increasing the total acidity of distilling material to catalyze esterification is with freeze concentration also known as jacking. Freeze concentration, which is sometimes called freeze distillation or fractional freezing, separates compounds by melting points. Distilling material that is freeze concentrated ends up higher in alcohols, aroma compounds, and total acidity.

Ciders are known to have been freeze concentrated and the process may have given early American cider brandies the name Applejack. There is no clear historical references to ciders being freeze concentrated before distillation, but it seems likely that it was practiced if inadvertently. Ciders were probably distilled later in the winter when there were less farm chores to be done and by that time casks of cider stored in the barn would start to freeze. Ice crystals would form on the top which could be separated and a zingingly tart, higher alcohol beverage would result. Supposedly, concentrations as high as 30% alcohol can be achieved. The elevated alcohol content may have even negated the need for a second distillation. Freeze concentration before distillation was rumored by the mid 20th century flavor chemist Joseph Merory to create the highest quality fruit eau-de-vies, but no explanation of the underlying science accompanied his claim and it is not known if any commercial producers use the technique. The increased total acidity that results from freeze concentration likely increases aroma creation in the still through acid-catalyzed esterification.

Each phase of double distillation in a pot still is carried out slowly to maximize esterification [this may not be true if the second phase can be characterized by a net loss due to hydrolysis]. Applying too much energy can result in super heated hot spots in the boiler. Hot spots may break down yeast cells and reducing sugars generating favorable aroma compounds, but too many may also create off aromas by scorching. A pot still is thought to operate at non-equilibrium because there is no reflux beyond what naturally condenses on the walls of the still, but running the still too fast by increasing the energy applied to the boiler has been observed to change the distribution of the fractions. The observation may be the result of super heated hotspots volatilizing components in unpredictable ways [This is incorrect and the real reason is that reflux, due to the shape of a pot still, is more significant than you’d think. Run the still too fast and you challenge that natural reflux thus altering the fractions.]. Avoiding hot spots with a slow distillation may increase the predictability of fractions and therefore also increase product consistency. [Not challenging the natural reflux of the pot still in the second distillation will lead to a higher proof product and thus less spread out congeners and therefore opportunity for a larger hearts section.]

Not all fatty acids form esters in the first run. Often more time under heat is required so many of the fractions that are separated are recycled in the next batch. When you consider the linkage of batches, double distillation in a pot still ends up employing more fractions than people think and distillers often use various names confusingly. To understand double distillation it is useful to consider where every fraction ends up and why.

The first phase of double distillation in a pot still, often called a stripping run yields a foreshots (this term has different meanings historically) fraction that is discarded, a heads and tails fraction that are both recycled, a hearts fraction that is passed on to the second distillation phase and a non-volatile fraction that is often employed to recycle fatty acids that do not volatilize and to increase the total acidity of the next fermentation.

Under non-equilibrium distillation, what appears in the very beginning of the run can change significantly depending on the alcohol content. Besides above recognition threshold amounts of ethyl-acetate and acetaldehyde (that smell like nail polish remover) as well as methanol, the discarded foreshots of the first phase of double distillation may contain a lot of fusel oils that eventually move to the tails of the second distillation where the starting alcohol content is significantly higher [The foreshots may even contain very high boiling point fatty acids that physically clung to the condenser, but are dissolved by the high ethanol content of the beginning of the next run. This residue become significant when a still is shared across different product categories.). Fusel oils do not benefit from being recycled and are often only desired in low concentrations. Fractioning is used to separate fusel oils but they are also limited by manipulating fermentation variables to minimize their production. Fusel oils are the byproduct of stressing yeasts so distilling material is typically fermented to much lower alcohol levels than yeasts are known to produce in theory.

Not all distillers make a heads and tails cut during the stripping run. Some opt to pass everything along to the second distillation which might be due to a lack of involvement. The first phase of double distillation sees much more time under heat than the second phase as well as contains significant acidity to catalyze esterification so separating fractions high in aroma precursors and recycling them to the next batch’s first phase may result in the best opportunities for aroma creation. Some distillers only opt to return a portion of these heads and tails fractions to the next batch. These distillers are not trying to create the fullest flavored spirit possible but rather something elegant and refined.

During the second phase of double distillation, the alcohol content of the distilling material is much higher and all the non-volatile acids have been separated leaving nothing to catalyze esterification. Esterification continues to happen to fatty acids that have made it over into the second phase [Esterification continues, but so does hydrolysis which breaks up the esters and there may actually be a net loss of esters but no literature states a rule of thumb for what happens to ordinary esters versus more desirable extraordinary esters]. The increased alcohol content increases the rate of esterification in a way that may partially make up for the lack of significantly total acidity. The second phase is separated into five fractions. A foreshots fraction is discarded while a heads and tails fraction is taken and a percentage recycled during the next batch’s second phase. The hearts fraction becomes the final distillate while the non-volatilized fraction is discarded. The non-volatilized fraction of the second phase which is mostly water also likely has a lot of congeners in common with the foreshots of the first phase.

When cuts are made and it is decided how much of the heads and tails fractions will be recycled or discarded, it is important to note that not all fatty acids and their esters are created equal. They are definitely not all desirable. The esters of longer chain fatty acids are typically more desirable than the esters of shorter chain fatty acids like acetic, lactic, and butyric. Cutting a spirit will often involve separating undesirable shorter chain fatty acids and their esters, but like the higher alcohols, many of these components are better controlled and minimized by manipulating fermentation variables.

A column still also has many options to generate aromas in the still by the continuous recycling of small fractions that are high in aroma precursors. Once the still comes close to equilibrium a fraction that is high in volatile fatty acids is isolated and recycled through the column to increase its time under heat. A column still can increase the time under heat of small fractions while not investing in heating the rest of the volatile fractions which saves significant amounts of energy. The juggling of small fractions can produce large amounts of esters but the process becomes detached from other secondary aroma creation processes that typically happen alongside esterification during a slow double distillation in a pot still. [I don’t know how to explain this relative to the simultaneous esterification/hydrolysis phenomenon. I suspect the the fractions are relocated to a part of the column where alcohol is particularly high favoring ester formation over ester break up. Where alcohol is particularly high there is little water to break up the esters.]

Believe it or not, fatty acids have the potential of escaping esterification and making it all the way to the barrel. Barrel aging presents yet another opportunity for esterification (or even the breakdown of esters and other aroma compounds), but some distillers choose to remove many fatty acids by filtering through activated charcoal or using the chill filtration process. Untreated spirits have the potential to become cloudy upon dilution which many consumers are thought to object to. Particularly high fatty acid contents can also cause the distillate to appear cloudy after either phase of double distillation in a pot still.

Following the path of aroma precursors and their reactions can help distillers make more sense of the various fractions and where they end up. The extent to which fractions are recycled illustrates how integrated production runs are. Understanding the various options for operating a still when new aromas can be formed provides a basis for the experimentation required to sculpt distillates. This look at aroma creation is probably oversimplified by focusing on fatty acids and esterification as there are so many other reactions.  Esterificaiton is just a starting point and eventually as involvement deepens distillers will eventually build an understanding of the other aroma creation processes.

Creating beautiful spirits is more than just operating a still.  Aromas born in the still, whether a fault or a feature, have precursors that can be traced back to fermentation variables or the source material. Reasonable guidelines for operating a still will free the distiller to take a deeper look back at fermentation and then eventually a further investigation of the source material, be it grains or grapes. Extraordinary aroma born in the still comes from extraordinary precursors. So many variables may be daunting, but that is why spirits are so revered and so special. Exploring the potential for aroma creation from selection of the source material all the way to bottling may help small distilleries create new classes of full flavored spirits which allow them to differentiate themselves from larger distilleries making more restrained styles of spirit. Awareness of all the considerations that go into producing a full flavored spirit will certainly increase appreciation for the work of any deeply involved producer.

[edited to add: One things this post doesn’t do is differentiate the common esters. In another post I spend a little bit of time musing about the most generic of esters, ethyl-acetate which is not widely understood. I connect this congener to the threshold idea where for some reason we want as much of it in a spirit as we can without recognizing it. This can be said as we want it above the absolute threshold but below the threshold of recognition. Understanding these thresholds might teach us about the distillation of highly aromatic spirit concentrates that eventually get blended down. Certain terroirs of sugar cane or grapes or even certain apple varieties from a diverse orchard might be treated differently during production to maximize aroma. These concentrates cannot stand on their own but have to be blended down to keep certain key generic congeners in check. I haven’t found any great literature that specifically explains the concentrate idea so I’m just musing about it in theory.

Another ester issue of note that can differentiate the pot still from the column still is that because higher alcohols tend to stratify and bunch up in a column, more esters of higher alcohols have the opportunity to form such as amyl esters which are undesirable and considered flaws.]

Bostonapothecary; A Retrospective

I’ve written quite a lot of posts over the years so I thought it might be time to make a top ten list of the coolest things that have happened at the bostonapothecary. If you look back at older posts the evolution of my ideas is quite apparent. I’ve kept the old posts up to show where I’ve been.

The content is definitely getting more neuroscience-y and more linguistic in nature. Some of the older posts focus on analytic techniques like hydrometry & refractometry, and distillation. I never really posted a lot of cocktail recipes here because this blog was just a counterpart to participating in egullet.

It might help first to show what people were most interested in (ranked by hits):

1. Dry rum & dry gin I like mine wet. This post started as a look at the acidity of spirits which I was never able to revisit. Countless people were referred to the post by search terms such as “pH of gin” or “acidity of gin”. I think people find the aroma of juniper to converge with gustatory-acidity and therefore wonder if there is non-volatile acid in the gin. These constant queries support my idea of categorizing aromas in terms of gustation. With this method juniper would be olfactory-acid.

2. Ice wine grenadine. This post really blew up after Dave Viola linked to it in the first comment of Jeffrey Morganthaler’s recipe for Grenadine. Morganthaler must get an astounding amount of hits if I get so many from him. It is a great recipe and you can do pretty astounding things with the technique. As widely read as the recipe was, I’ve never heard of a bar program actually using it. Slackers. It is bonkers ridiculous.

3. Vermouth: Its Production & Future. This is good stuff. When I started collecting all the sources in Maynard Amerine’s Annotated Bibliography of Vermouth many of the sources were from mid century wine & vines and unfortunately not yet indexed by google. I inter-library loaned them all, re-typed them, and made them more easily available. My bar program back at Dante was the first to make its own aromatized wines and now there are several hundred around the country. I re-typed several other articles from Wine & Vines such as Developing the Vermouth Formula, The Importance of Vermouth, Revolution in Vermouth, Vermouth… Some Practical Hints, and Gold Medal Sweet Vermouth. All of the study of vermouth helped me get into practical wine analysis such as using refractometers and hydrometers which really took my bar prep to a new level.

4. Deconstructing Campari. An astounding amount of people wonder if Campari has sugar. In many cases I suspect it is for the sake of calorie counting, but I also think many searchers have some sort of sensory curiosity. I was making versions of Campari where I dehydrated it and reconstituted the non-volatile fraction with another spirit to the same alcohol content. What I found is that volatile-olfactory-bitterness (lost when you dehydrate!) is astoundingly important to defining the character of Campari. My reconstituted versions lacked this aroma-of-bitterness until I redistilled those spirits with wormwood. I also went so far as to grow rock candy in bottles of Campari but they picked up no bitterness. What I have left to do now is cut Campari in half with a vacuum still and then precipitate the sugar out of Campari (such as how the rock candy grew) then rejoin the two halves. I can then reshape campari into lower sugar, higher alcohol styles of amaro like fernet, malort, or gammel dansk. I could even re-add the volume of subtracted sugar with a source of my choice such as a strawberry tree honey.

5. Deconstructing Sweet Vermouth. People wondered over to this post with a curiosity for how much sugar sweet vermouth had. My methods for revealing sugar content grew over the years making this post obsolete. Now I favor hydrometry and have found specific gravity tables to reach low enough alcohol contents to measure the aromatized wines. Unfortunately I suspect my margin of error is 30 g/L.

6. Chamberyzette. When curiosity for aromatized wines grew, curiosity for what the hell Chamberyzette is also grew. It is hard to believe that it is not imported. I was told once that their production is in a sad state and had degenerated into artificial flavors. I made replicas for a while by manipulating bianco vermouths but eventually M&R rose vermouth became imported and I fell in love with it.

7. Fenaroli’s Handbook of Flavor Ingredients. This guy is pretty wild. The book is a two volume tome on artificial flavors but has an extraordinary chapter on constructing amaros which shows that many of these super-consultant flavor chemists were interested and involved in the amaro trade. Fenaroli describes “special effects” and techniques of creating differentials of expectation and anticipation in amaros such as distilling a bitter principle then re-infusing that distillate with more of the bitter principle to end up with something like 2x olfactory-bitterness 1x gustatory-bitterness.

8. Bombardino! Dante’s aunt Anna turned me on to this Italian specialty. She said as a child she was too poor to afford cream so she would put tempered egg yolks in her coffee. My recipe got a little bit of an update with fluid gels are our future but it should probably be updated again since I’ve learned a lot more about it.

9. Sweet Potato “fly”. This is just awesome and the idea has taken my ginger beer to a new level. The sweet potato ginger beer post needs a bit of an update now that I’ve developed a new carbonation technique. I think I also need to re-evaluate how much spice I get from the ginger skins. The best results might come by heating the skins in ginger juice or going the all cayenne route. I juice my ginger while others only macerate. After I juice I probably need to make a tea from the separated skins to capture their piquancy. Those that just macerate with cut up ginger may get the piquancy but lack a lot of aroma from the juice.

10. Hand Made Creole Shrubb. Creole Shrubb is awesome and it has been a pleasure to watch it become more accessible over the years. Unfortunately for the Clements, I loved Creole Shrubb so much I started making my own. I took an exploration of orange liqueurs pretty far and even ended up reconstructing Joseph Konig’s curacao from 1879 and learned the secret of its sugar content (maximum of solubility!). My technique of assembly became really good and I think I could quickly make all the orange liqueurs at a very high quality level for my next bar program. We used only house-made orange liqueur for my last year at Dante which probably only added up to 50 liters.

11. Amer Picon Replica. There is a lot of interest in Amer Picon but I kind of gave up on it. I fell in love with Cynar and it was enough for me. In the end I suspected what everyone was missing was a focus on tonality of orange aroma and Picon’s was likely modified from an aromatic sugar source like malt. If you think about it, Picon & beer could only be relevant so long as it was cheaper than the Chimay it set out of emulate. This Belgium ale role model also reveals the secret of its aromas. I’ve learned a lot more about the aroma of grains recently so maybe I’ll pick it back up again. My flaked rye aromatized bourbon might warp into a sexy flaked rye aromatized triple-sec.

12. Reward System Theories. An astounding amount of people are searching for these terms but I don’t really know why. The ideas are gigantic and the implications are far reaching. I hope to take it further. I wish some people would comment!

13. Sweet Rebellion: a short theory of acquired tastes and an unsavory explanation of harmony. A growing amount of people are interested in acquired tastes. Acquired tastes are under appreciated and a theory of them will contribute answers to 100 million dollar questions. If through spreading acquired tastes we can cut empty calories from the American diet the results might be worth hundreds of millions in health care savings.

14. A theory of wine-food interaction. This is awesome stuff and I’m glad a lot of people have read it. It did unfortunately generate no real dialogue. I updated some ideas here in contrast enhancement (in space and time) for wine & food interaction. All the explanations we need to understand pairings are contained (but he makes to direct connections!) in Gordon M. Shephard’s Neurogastronomy.

15. Hercules: A liqueur interpretation or replica. Hercules is pretty cool. I revisited some of the bottles from this post recently after they slept for almost four years and wow were they extraordinary. All the interest Erik Ellestad has generated in the Savoy has generated a lot of interest in Hercules. It is wildly avante-garde in concept but so elegant as it goes down. I need to make this again and see if I can find any other notes I took pertaining to its construction.

Now here is my top picks for what people should be checking out.

1. Advanced Aroma Theory Basics. This is my crowning achievement and is an excerpt from my book on distillation. I explain the history of many of our metaphors. I cover their chemistry as well as their neuroscience (though that could be beefed up) and I give ideas for how many of them could be usefully elaborated. The language learned dramatically increases flavor literacy. Wild things happen with literacy’s fragmentation. Patterns emerge that can guide our creativity. Marshall Macluhan describes the gift of literacy as being able to act with out reacting. Many writers like Barb Stuckey are now thinking flavor literacy is important to controlling food cravings (detachment!). This new set of language is also the basis for understanding wine pairings. Other cool exercises in language are the Attentional Features Primer or Advanced Oversimplification Basics; The Ordinary and the Extraordinary.

2. Advanced Wine & Food Interaction. Here I start to explain all the contrast enhancement that happens in wine and food interaction. My first set of ideas started here and many got refined and validated by Gordon M. Shephard’s Neurogastronomy. The future of this lies in wrapping articulate language around the mach bands that are formed in a pairing (a mach band being the “line” over which contrast enhancement changes). Neurogastronomy explains what happens in the mind but we cannot make any practical use of it until we have a more advanced set of metaphors to unravel the synaesthetic experience of perceiving flavor. If olfactory-sweetness converges with gustatory-sweetness, language creates the awareness to differentiate the two. We cannot find patterns without language! Almost seven years ago back at Dante I started to create a new language for categorizing wine pairings and explaining all the reactions that happen. My first post ever was describing Maccheroncelli Primavera with Falanghina. I even explored cheese and vermouth pairings. I think I stopped with this interesting one. My goal now is to revisit all the holy grail pairings from WTDWWYD with a few friends and describe all the reactions in terms of mach bands. Very expensive. I need some sort of grant money to take it where it needs to go.

3. Measure carbonation with a kitchen scale. This is very big because handling carbonation well has been so elusive for beverage programs. I’ve tried everything (one bar in Vegas adopted this bottle carbonation technique) and I’ve spent thousands. I even described the limitations of bottling under pressure. I’ve even gone so far as to build a plastic foundry to produce my own equipment. After much work I can report carbonation is solved. My new product is a Champagne bottle manifold with Cornelius quick disconnects. The dissolved gas added to the liquid is simply measured on a kitchen scale that can handle a tenth of a gram. The dissolved gas has a weight and that weight is easy to measure (7g/L for highly carbonated sodas). You can even estimate if you want. I just acquired an Ohaus kitchen scale that can do 4 kilos by a tenth of a gram ($200) so now I can precisely measure the gas I add to Champagne magnums! I can even apply gorgeous counter pressure to sparkling wines. I can even add extra gas to beers! My product will soon be on sale for $100 then all you will need is a gas tank, regulator, and a nice kitchen scale. Solved, done, boom, and you serve out of gorgeous Champange bottles! Once they absorb enough gas you take off the manifold and put on a bottle cap (size 29mm). This could cost a bar $500 to do it right (tank, regulator, a few manifolds, scale, bottle-capper) but if you are smart you can take your new skill set and switch over your ISI whippers in the kitchen to cheaper tank gas using these new high end quick disconnects. That $500 will melt away quickly in saved cartridges. Performance will also go up! This will all be covered in my next post. If your restaurant says they can’t afford it buy your own fucking equipment! When you prove its a good idea, maybe they’ll pay you back. More to come!

4. Sweet Rebellion: A Short Theory of Acquired Tastes and an Unsavory Explanation of Harmony. This was pretty cool. It is unfortunately an ignored field of study. It went a little further in Culinary Aestheticism: A Tale of Two Harmonies where I attempt to explain how the symbolic world manipulates the harmonic bounds of the sensory world and vice versa. This stuff is critical to taking the empty calories out of our diets and adding new food sources to our diets such as they’ve been doing at Noma in Copenhagen. If we as a society would do something with these ideas we might shave billions off our health care budget. An entire country of black coffee drinkers? I could slash diabetes by 20%. MacArthur foundation help a brother out? I need to somehow finance an experimental gastronomy programs to learn more about this stuff.

5. Using simple hydrometry to find the sugar content of commercial liqueurs. This took many false starts and a winding path. Hopefully I made amends for bad refractometer advice I gave Eric Seed years ago. My first method for accurately revealing sugar contents had me sacrificing large sample sizes which was really expensive. This technique can be a really useful tool for bars making their own nano scale products or commercial producers trying make locally sourced and produced clones of commercial products. The chart can also help find patterns and almost quantify acquired tastes into numbers and ratios. Every bar should own a hydrometer.

6. Advanced Superstimuli Basics. I thought it was particularly cool to compare cocktails to super normal stimuli. The two guys that discovered the concept won the nobel prize! Understanding them can help us make more therapeutic drinks. An understanding founded in the culinary arts can also help us recognize them in other aspects of our lives where they are often dangerous. Nature published a paper on Flavor Networks and Food Pairings which got tons of attention but they never made any connections to the superstimuli phenomenon that is the motive of all our creative linkage. I’d love to get a hold of their data and computational expertise. I suspect a better understanding of all these things will help us take on more food sources as the pressure for sustainability grows.

7. Advanced Kegging Basics. This was the beginning of cocktails on tap and it turned into a phenomenon. I hear that almost every new bar in SF has a cocktail on tap program. Apparently the two or three people I influence are astoundingly influential. One of the first times it got put to the test was when I made cocktails for 400 with my crazy boss. Much of it started with a method of faking wine on tap to prove that there was a market and consumers wouldn’t be scared of it. Wine was simply taken out of bottles and put into kegs. Fake it till you make it! With the kegs you can also do stuff like pressure filtration. Worlds largest whip cream canister! I also suspect you can use kegs and some sort of cavitation technique to de-gas large volumes of liquids that other people have used centrifuges to do (you blast it with nitrogen to force the oxygen and CO2 out of solution. I think it works similarly to the process of pressure casting plastic or bronze). And all the equipment is really affordable!

8. Basket Pressed Pineapple Juice. This was wildly successful and yet again I don’t think any bar programs have picked up on it. I acquired a small (five gallon) home cider maker’s press and tried to see what besides apples could go in it. Pineapples were the most extraordinary because people have such a hard time juicing them. Strawberries were beautiful (either freeze/thaw them or soak them in hot water to loosen the pectin). The press will allow your prep to scale up dramatically. I started accumulating gallons of juice from the peak of various seasons in my freezer to unleash later on the thirsty hoards. The press was only about $400 compared to the $1000 of a large capacity centrifugal juicer that can’t even handle all the fruits as well (they also aerate the juice killing its lifespan).

9. Nano-distillation. In the end I wrote an entire yet to be published book about exploring beverage distillation on the smallest scale possible. A few of the first recipes such as the Absinthe and the Genever made from malta goya appeared on the blog before I stopped posting recipes for the sake of the book. The recipes have evolved over the years and the additional recipes from the book are wildly fun. I’m trying to have a friend look at the book before I send it to the publisher. I’m hoping it can become a classic and pulled together huge amounts of information about distillation that have never been seen under one roof.

10. Home made orange liqueur. A project to make a terroir driven orange liqueur for the bar years ago got really out of hand and wow did I learn a lot of things. Things started back here with Newman’s own Creole Shrubb but gradually got more sophisticated. There were various deconstructions of Cointreau and eventually I even re-created Joseph Konig’s curacao from 1879. These ideas are really useful to new distilleries and to bars. The recipes work astoundingly well and can be a solution to numerous problems.

11. Instant aging, Fernet 151, and DIY Barrel Proof Overholt. I almost forgot this technique. They were wildly fun. 69 Colbrook in London linked to the instant aging with vacuum reduction technique though I’m not sure if anyone actually used it. Later on I discovered you can use an Excalibur food dehydrator instead of a costly vacuum reduction setup. Everything is elaborated further in my distillation book so things got neglected on the blog. I saw tons of incoming links from egullet where the technique was discussed but no testimonial of people trying it. One of the favorite uses was on Kuchan’s peach brandy. Un-aged it tastes like bubble gum and is gross. Fake age it with some bourbon and it is move you to tears beautiful.

12. Advanced Nut Milk Basics. This was a cool one and I know there are quite a few centrifuges out there in operation, but I don’t think anyone else but Dave Arnold’s crew is taking nut milks too seriously. Over on egullet I posted a string of cocktails featuring nut milks, orgeats, and decadent nut milk heavy creams (concentrate the fat!)

Thanks for checking things out! don’t worry there is more to come.

The Manhattan: Prior Convictions and Ulterior Motives

“The value the world sets upon motives is often grossly unjust and inaccurate. Consider, for example, two of them: mere insatiable curiosity and the desire to do good. The latter is put high above the former, and yet it is the former that moves one of the most useful men the human race has yet produced: the scientific investigator. What actually urges him on is not some brummagem idea of Service, but a boundless, almost pathological thirst to penetrate the unknown, to uncover the secret, to find out what has not been found out before. His prototype is not the liberator releasing slaves, the good Samaritan lifting up the fallen, but a dog sniffing tremendously at an infinite series of rat-holes.” -H.L. Mencken

“The rush to expertness compromises all interrelationships” -Marshal Mcluhan

I hear people quite often making proclamations of what constitutes the “best” Manhattan. We all know my feeling about the word best. These people seem to only accept one version as true and ideal. If we thought about, and maybe outlined, all the possible motives that exist for our attraction to a Manhattan maybe we could accept many types.

One of the most noble motives that guides Manhattan construction is flattening a sensory path to perceiving the aroma. Experiencing the extraordinary in aroma is very important to cementing and retrieving memories. In the multisensory perception of flavor, olfaction is the hardest sense to perceive and the other senses typically end up being attentional distractions that often pull us away from olfaction (there is salt the aroma enhancer and then at some point there becomes salt the aroma distractor. Chef’s usually bark things to their line cooks like “too salty!”, but what if they elaborated and said something more articulate like “you went from enhancing the aroma to distracting from it”. Would the young line cook learn faster how to properly salt?). When we stir a Manhattan as opposed to shaking it and dissolving gas we limit texture distraction. When we compound a Manhattan in a certain ratio of whiskey to sweet vermouth we simplify gustation so as not to distract from aroma. Believe it or not we require a certain amount of sweetness to fix gustation at its most innocuous point in relation to perceiving aroma. Too much sweetness and we reach a blinding zone called cloying. Too little sweetness and aroma is suppressed. This lesson was first mastered by port wine producers who created the 18×6 template. For port, 18% alcohol puts the wine at the minimum of preservation so as not to be a distraction. Drinkers of dry wines complain that even alcohol contents as high as 15% can be distractions from aroma when there is not residual sugar. A brix of 6 is just over 60 g/L and is enough to hide the extra percentage points of alcohol while simultaneously flattering aroma. Sweet vermouth typically has a sugar content near 165 g/L so when diluted 2:1 they approach the wisely chosen sugar content of port. Alcohol in a Manhattan is certainly not innocuous but rather is part of the drink’s charm.

We are not solely in love with aroma. Many of us demonstrate a love of other attentional features like alcohol and acidity. Many imbibers scoff at the 2:1 aroma emphasizing formula. And what do we make of those people that happily drink shaken martinis with “tired” vermouth? Are their motives any less noble? What are their motives anyhow? Drinkers that enjoy ratios such as 3:1, 4:1, or the infamous perfect Manhattan are not afraid to compromise aroma by making the other features more salient. These imbibers find repose in exotic styles of dryness. The brash attentional nature of these Manhattans are thought to dispel anxiety and with that said we might have just found their motive. If the Manhattan simply becomes a vehicle for attentional therapy there quite a few ways to skin the cat.

If our motive is to thwart complacency it might make sense to have a formula forced upon on us through random old school free pouring where we will just learn to love it. Many people enjoy this randomness, but we are quick to chalk it up to a lack of understanding their options. Free pouring and random recipes are cocktail movement blasphemy but they may not have been without positive effects.

Adding Angostura bitters echos and alliterates facets of the whiskey turning the sum into a super stimuli. The extraordinary expression of aroma that is Angostura bitters can push ordinary whiskey and ordinary vermouth into the extraordinary. One of the most salient features of Angostura bitters is their massive amount of tannin which stimulates the haptic sense which operates via the Trigeminal nerve. Adding certain levels of haptic data to a flavor experience is known to change contrast detection, amplifying aroma. Olfaction often has to be turned on and our ability to do that becomes less easy as we age. Besides their aroma, the tannins of angostura bitters may help us smell more of our Manhattan.

The Manhattan differs from its counterpart the old fashioned. The old fashioned is a clean cut super stimulus like the Venus of Willendorf or basically whiskey with a set of outrageous breast implants. Whiskey, especially bourbon, features a distribution of aromas that both increases the perception of sweetness and decreases it. Tension exists between the aromas and we are attracted to the relationship. When we add an orange peel we exaggerate the olfactory-sweet aroma in the whiskey and when we add Angostura bitters we exaggerate the olfactory-dry aromas. Whiskey also has tannins that stimulate the haptic sense and Angostura bitters adds to those. The sugar that is added makes the aroma all the more apparent. The tension that exists within the whiskey is widened making it feel similar but become more attentional (The same series of relationships exists when we add dry vermouth to gin and make a martini. The juniper aroma converges with gustatory-acidity and the most salient feature of dry vermouth is its acidity hence the martini being the super stimulus version of gin). A Manhattan could probably also be seen a super stimulus but probably one that is less clean cut.

Many people that claim to strongly dislike sweet drinks can enjoy a Manhattan because the aroma is typically redeemingly extraordinary which leads to a great rule of thumb. Among people with well entrenched acquired tastes, when we flatten a path to olfaction by holding all the the other senses at their most innocuous (a sweet drink) the aroma presented must be extraordinary or the experience will be seen has unharmonic.

When we can better articulate our motives we can better achieve our goals. We can also squash elitism, annoying false claims of authority, and pretensions. When we understand what cocktails actually do to us such as with anxiety and complacency thin claims of spirit superiority start to fall apart. Drinking also becomes cheaper because we start to allocate our money better. When we understand the ins-and-outs and order of operations of the multi sensory perception of flavor, unsubstantiated elitist bartenders are separated from matter-of-fact sensory scientists. When we actually recognize acquired tastes and their value we will treasure them when we find them in others. When we learn their patterns we will have no myopia to their various shapes. When we unravel the mechanism by which we learn to like challenging experiences, we will all be more sustainable.

Unfortunately it is never simple. So much of how art comes to be and what it does to us is accidental. Because they are an acquired taste, so many people started drinking Manhattans with something to prove. This powerful but not so noble motivator helped them acquire the taste rapidly. In the end the end these drinkers discovered an avenue of attentional therapy. All’s well that ends well. Happy drinking.

Instant Aging: Vacuum Reduction Yields Barrel “Bouillion” Cubes

[As I’ve learned since through performing maturation experiments and reading a lot of journal articles, there are lots of flaws with my theory of what barrels contribute but you can still use the idea to create a very accurate barrel essence to add to other finished spirits]

After dissecting many spirits, I’ve come to realize that the vast majority of sensory attributes that a barrel contributes to a spirit are not volatile at the boiling points of ethanol and water [this fails to account for the significance of the angel’s share]. What this means is that we can remove the volatile constituents and end up with dried barrel essence. We can then introduce a solvent such as an un-aged fruit brandy or aromatic bitters and synthesize the character of barrel aging by having the perfect ratios of non-volatile compounds.

Vacuum reduction is a great tool for reducing a barrel aged spirit such as bourbon down to a dried powder because it reduces the boiling point of water enough that the flavor compounds will be as un-effected by heat as possible during evaporation (no process volatiles). My vacuum reduction rig is a Comeau vacuum aspirator (acquired for $75!) attached to a vacuum flask ($15) heated by a hot plate (a stove on low with a double boiler substitutes well). A double boiler always needs to be used because when you run out of water, the solids will scorch instantly. If your solids clump when you try and reconstitute them, they likely got scorched.

The cost of this process is essentially the cost in bourbon of the volume you want to artificially age. For example one ounce of bourbon is sacrificed for every one ounce of peach brandy you want to treat. An ounce of bourbon from a handle of Evan Williams costs about fifty cents.

For the proof of concept, 100ml of Old Granddad was reduced to powder and then the barrel essence was reconstituted with Kuchan brand Indian Blood Peach brandy. The results are very impressive with the un-aged spirit tasting very much aged. I never really enjoyed the un-aged peach brandy previously, because it seemed to resemble bubble gum, but the barrel essence seems to add attributes that push the ordinary into the extraordinary.

And this is all legal…! People are willing to spend tons of money reducing Campari to powder to rim a glass. This is significantly cheaper (after you spent $100 on some used lab equipment) and probably much more interesting on a sensory level.

[I’ve used this technique quite a bit, liters at a time, and have settled upon using an excalibur food dehydrator over a vacuum reduction rig. I’ve also digested quite a few brilliant journal articles on aging. This technique is a great predictive tool for distilleries doing new product development but you cannot be naive about the results and need to know how they differ from the real deal. A new make white dog, for example, would not be instantly aged and rather would require months to calm down and come to equilibrium. No angel’s share would be accounted for either. All in all, the results are better than any other fake aging technique and can be done affordably and accurately in volumes as small as 2 oz.]