March 2013 – Boston Apothecary

Planet Underwined

This isn’t by James Cameron the film maker who would have only been 18 and probably its this cool. This is James Cameron the famed british journalist, an Indiana Jones type who probably inspired the other Cameron to live up to his name.

Planet Underwined is the favorite article I’ve unearthed so far in the old WineMine quarterlies I’ve been collecting. Thanks James!

by James Cameron from WineMine no. 24 Winter 1972

When I see the phrase ‘All the world’s wines’ I detect a fallacy; it is like promoting the International Haggis Company, or Caviar from the Four Corners. Drink is ubiquitous, thank God, but wine is specialised. I suppose at a guess that something like seven-eighths of the world’s surface doesn’t make, sell, or know anything about wine. Wine is a European phenomenon (with North and South American descendants, as with people, and a cousinage in Australia). If you quote scripture at me to prove it originated in the Middle East, then I can only say they lost the trick some millenia ago.

It is true that in the days when Cairo and I were on speaking terms I once got a present of a half-case from Egypt, if you please. I liked to decant it and watch people huffing and snuffing and screwing up their vocabularies to identify this awful stuff; I would then say it was an unpretentious little Omar Khayyam from the south slopes of the Great Pyramid, which it was. Talk about unassuming; after a while we used it in salad-dressing.

So all the world hasn’t got wine. The earth’s greatest land mass, Africa, has none at all south of the Mediterranean littoral, until you come to the Cape (and I do not come to the Cape). I see that now even the Algerians are tearing out their vineyards and putting the land back to the plough, partly to do their late French owners in the eye and partly because they want grain more than grapes, silly them.

However, what has always puzzled me is that the most extensively varied and populous region in the world, Asia, never caught on to viticulture at all in any serious way. My mother-in-law, who is a South Indian, makes a fair quantity of wine at home in Bangalore, but it isn’t what you’d call wine; more of a kind of curried Dubonnet. The fact of the matter is there is no wine known to man that doesn’t taste like poison with Indian food. The only thing is beer or coco-nut water. Great chunks of the sub-continent are Prohibition now anyway, and even with a Permit you will find your whisky costing some nine or ten pounds a bottle. In these distressing circumstances the thing to remember is the great Cottage Industry, pot-still arrack. Do not be put off if it comes in a coco-cola bottle or and old oil can; it is very excellent indeed, particularly when there is nothing else. Ask Peter Dominic to lay down a gourd of two for you and see what he says.* [* ‘Oh Gourd!’ -Peter Dominic]

So why is there no native wine in the immense stretches of Asia, where there is every kind of geographical and climatic condition, and several hundred million people of subtle and cultivated taste? I do not know. In the French days vast quantities of wine were imported into what was then Indo-China and is now Viet Nam : where did it go? A year or two ago, in Hanoi, I made enquiries at the Reunification Hotel–which had been a reasonable wine-bibbery in the colonial days when it had been the old Metropole–and after a long search they dug up for me two very, very archaic bottles of burgundy; something like twenty-five years old. After we had filtered it through the cork-dust and batshit it was so dreadful we had to pour it down the basin, where it slopped and gurgled resentfully all night. And that, according to the people’s democratic butler, who was a capstan-lathe operative by trade, was all there was or ever would be. Why don’t you make your own, since you could? Because we have better things to do. In the circumstances, with the American bombs dropping on the ricefields, that seemed reasonable.

So in Hanoi you have to make do with beer, which in Vietnamese is considerately called ‘bia’, or a lethal distillation called leu moi, the ‘new rice’; one gets quite a start when one sees customers filling their lighters with it.

The great mystery to me is China. I have spent some time there, and long ago conceded their gastronomical dominion over the rest of the world, once you acknowledge that there is no such thing as ‘Chinese food’ any more than there is a ‘European food’, and that from one end to another it differs every bit as much as say, Scandinavian food and Sicilian food. But why no specific Chinese wine? They have highlands an they have lowlands; they have tropical coasts and Siberian hinterland; there seems to be no convincing reason why they haven’t been making wine for five thousand years, except: It is not our custom. It is not their custom to drink the grape any more than it is their custom to wear wool. Cotton, yes, and silk, yes; wool no. The Chinese are a great and sublime people, in my view, and (despite the Cultural Revolution) Conservatives of the deepest die; when they start making wine they will start wearing Harris tweed, and that is no-when.

Instead you will drink huang chou, which is food-wine made of rice like sake, tasting of lukewarm Cyprus sherry, or mao-t’ai, which is the stuff all the fuss was about when President Nixon appeared on the world’s telly trooping round the banquet-hall drinking hundreds of toasts out of a glass the size of a small thimble: no wonder, mao-t’ai is a splendid spirit; it is said they put it up in flasks made of granite because it dissolves everything else. It has saved me on many an Arctic evening in Peking. But it will never replace the lingering glass of plonk.

When I was staying in China, which was not too many years after the revolution and the advent of Chairman Mao, there was a great legend, or rumour, about some semi-forgotten community of French Benedictine missionaries somewhere in the interior who had been growing vines and making real wine for years; indeed some said for a generation or two, and that not only was it of uncommon quality but it used to be on the market in the abominable days of the Shanghai Imperialism. I tried in vain to track these brothers down. Some said they were up by the Mongolian borders, but when I got there I realised that the only thing you could make in those parts was ice-lollies. The brothers were reported up in Szechuan, somewhere around Chungking, but nobody there had ever heard of them. I never landed these people; their famous vintage is Chateau Feu-Follet as far was I am concerned. Yet the legend persists; a friend of mine, who is a professional China-watcher in Hong Kong, told me the other day that he had actually seen a bottle of this mystic brew, labelled: Bo Chou-lay 1970; Domine Mao Dirige Nous. This friend is a notorious liar, however. How else would a China-watcher live?

We must therefore conclude that the most populous nation on the planet, with some seven hundred million potential customers, knows nothing about wine. The Foreign Languages Press of Peking is not hanging on edition-time to translate this WineMine into Mandarin, Cantonese, Hunanese, and all the rest. They could not, in short, give a monkey’s. Nor could the Bengalis, the Rajputs, the Annamese and Tonkinese; leave them their rice-wine and their lighter-fuel.

‘All the world’s wine’ means, truthfully, ‘The wine of the small portion of the world that knows anything about it.’

But, my masters, what a proportion!

The WineMine Chronicles

I’ve collected texts on wine and spirits for years and Peter Dominic’s WineMine quarterly form the 1960’s and 1970’s has become my new obsession. WineMine may have been some of the first advanced foodie writing. The culture that Dominic and others like Andre Simon created is likely responsible for our modern world of fine wines. They educated people on fine wine and developed a market for it. Prices of wines they highly regarded skyrocketed and eventually other producers raised their quality to participate in this new fine wine market. The world of wine eventually fell into it. Once great wines were finally recognized and competed for, the investment required to make more of them across the globe was put into place.

WineMine was more than just about wine. it is also about food and travel and humor. The articles are still wildly interested after so many decades. The writing also gives us an excellent look at spirits and liqueurs of the era especially in then far flung places like rural france.

I’ll start to point out the highlights in a haphazard way and maybe even re-type the good bits. Journalist James Cameron has written my favorite article so far in issue #24 winter of 1972.

The first article that needs attention is A La Votre by retired journalist Joe Hollander from issue #25 from 1973. Hollander retired to rural France and writes of Provencal drinks “both above and below the legal line”.

Above the legal line:

“As for aperitifs and digestifs, apart from intensely publicized products like Dubonnet, St. Raphael and Byrrh, and Benedictine and Chartreuse, the floridly labelled bottles of Banyuls, Grenache and Muscat, all naturally sweet wines, and of Verveine de Velay, Izzara, Mandarin, Ambassadeur and other imaginative designations, are seldom disturbed from their resting places behind the bar and their labels would appear to serve mainly a decorative purpose. I have never yet seen anyone order a Suze (based on Gentian bitters), or a Bonal, prepared with Peruvian quinquina bark.

Below the legal line:

“Throughout the Midi there’s a more or less universal, if not exactly legal, cottage production of spirituous beverages going on behind the shutters of village houses.”

“Like most country women, Madame Allegre has probably never bought a bottle of branded aperitif or liqueur over the counter in her life. Nor have I ever seen a Vin de Noix, a Vin de Marquis, or a Peach Leaf aperitif served in any auberge, bar, bistrot, brasserie, buvette, cafe, estaminet, guingette or tavern in France–to say nothing of a liqueur 44, made of oranges and 44 coffee beans!”

“Madame Allegre take two average-size oranges, chiseling their skins so that she can insert 22 coffee beans between the peel and pulp of each. She then steeps the larded oranges in one litre of Eau-de-Vie, together with 22 lumps of No 3 size sugar (the popular domino-shaped sucre de Marseille) and a stick of vanilla. She keeps this infusion going for 44 days (that magic number again!), shaking it from time to time until the sugar is completely dissolved. She then removes the orange, presses them and pours back the juice they yield into the liqueur mixture, which can then be bottled and stored in a cool place.”

“For her Vin de Noix, seven walnuts are first steeped in a litre of Eau-de-Vie to produce the basic cordial. A quarter litre of this extract, together with 15 to 20 lumps of sugar, are then mixed with one litre of good red wine to yield two pints of Walnut Wine. The heart-warming thought is that you still have enough basic cordial in reserve to make another eight bottles.”

“The Widow Audibert, Madame Allegre’s neighbor, specializes in making a Vin de Marquis, otherwise known as Vin d’Orange. There are multiple variations of the formula; some use only the orange peel, some use the whole orange, flesh, pips and juice, others add one or more lemons. The wine used can be a robust red, white, or rose; eau-de-vie or cognac in varying quantities is essential, so is sugar. By experimenting, I have found the recipe A la Veuve Audibert to be not only excellent but the most economical.

Five whole, and preferably bitter, oranges cut up into the smallest possible chunks, with a lemon given the same treatment, are popped into a large glass or earthenware receptacle (I use a 10-litre glass bonbonne which I can cork) to which is added a kilogram, say 2/1/4 lb, of ordinary white lump sugar (some specify granulated sugar; others advocate pure cane sugar), then five litres of good red wine and one litre of eau-de-vie. Final additives are a stick or two of vanilla and a baby’s fistful of quinquina or Peruvian bark, obtainable from a chemist or herbalist.

Shake the receptacle well and repeat this at least once a day for a fortnight–but a month is preferably better. Using a large wire kitchen strainer to collect the orange debris, I then decant into bottles and find that I then have over six litres, or eight pint bottles, of first-class aperitif or dessert wine for around 30 francs (about £2.50) which is good going in any currency.

An Antillaise, based on a recipe that the Widow Audibert’s son brought back from Guadaloupe, requires strips of the skins of two fresh tangerines and one orange to be placed in a small bottle, together with a stick of vanilla, split and cut into small pieces, all then being covered with a quantity of rum taken from a litre bottle. Let this mixture infuse for a fortnight, then add the resulting extract to the remaining rum and a syrup made by boiling 1/2 kilo of sugar in a slightly lesser volume of water for ten minutes.”

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

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[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 19^th 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 20^th 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.]