Rum Comparatively: Understanding Anything Goes

[If you are a distiller, make sure you know about the birectifier]

I’m going to attempt to break some new ground here on comparative understandings of rum. A lot of this is based on new literature I’ve aggressively collected over the past few years. Hopefully I can sway one or two people or at least amuse a few of you.

The opportunity just arose for me to design my own rum at a local distillery that I’ve done consulting work for in the past. It is a long term project and it is allowed to be wildly progressive and possibly fail. The plan is to couple Arroyo’s super fractionated distilling techniques (that is probably my own term) with very old ideas in yeast propagation and fermentation. I want to make a heavy rum of terroir, despite molasses being an international commodity of which I barely have control over. I’m going to bring a sense of place mainly by creating a local foraged fruit starter for wild yeast and using some new ideas in the kinetics of microbial communities to promote a yeast that is seldom dominant to being dominant (there will be other posts on this). We will have light rum, a heavy overproof, and then of course an aged expression which will be a blend of various fragments. There may be room for accelerated aging of some of the fractions very similarly to Lost Spirits projects (perfume industry technique), but I suspect I’ll be maxed out for time before I can get those ideas off the ground. The project will use super fractionated natural aging which is widely practiced, but little understood, or ever a part of discourse so I suspect I will not need anything too exotic to get the results I’m looking for. There is a precedent for everything I aim to do, but what makes it progressive is that it has never been brought to New England or done on such a small scale. I will be deeply diving into distillation history and bringing it all to life.

This rum aims to tell a very New England, very Boston story. It reflects a love for the writings of progressive rum thinkers like those of the Jamaican agricultural experiment station, Harris Eastman Sawyer (the Harvard chemist who I previously identified as the architect of the modern New England rum style in 1900), Rafael Arroyo, the wildly progressive thinker who revolutionized most of the world’s rum production, and the thinkers at the Rum Pilot Plant (I finally found their annotated bibliography). There are many more like Valaer, Amerine, Guymon, Willkie, Murtaugh, Piggot and the student projects at Roseworthy agricultural college. Of course I wouldn’t have come across any of these thinkers without haunting the BPL, M.I.T. and having countless serendipitous Boston conversations.

Another way that it is a Boston story is that I’m personally a big product of Boston wine culture and the pursuit of terroir. The only way the land can shape commodity molasses is by bringing it’s microbial community and what better way to enhance that story by promoting the voice of a seldom seen yeast not harnessed outside of the Caribbean and not in acknowledged use (awesome exceptions keep popping up!) for almost one hundred years (details some other time).

I’ve long wondered why we don’t know more about rum’s actual production. There are a huge amount of practices that go absolutely unnoticed, not yet a part of discourse though other spirits categories like Scotch or Cognac attract a lot of scrutiny. I suspect a lot of it comes down to how much literature we have and a hallmark of my own perspectives and opinions is having a huge amount of literature that other people haven’t seen yet. I’ve slowly been attempting to construct a bibliography of 150 years of rum research with all the citations freely available. It starts with the great Agricola, W.F. Whitehouse in Jamaica reflecting after his distill-off versus the Irish interlopers and ends with the vantage point of L. Fahrasmane and B. Ganou-Parfait in the late 20th century.

There are a lot of glamour issues to why we don’t know more. We often discount the consumer as not ready for it. A brand’s life style image would be tainted by talking too much. Rum is also near always made at such large scales that it just isn’t romantic like a small winery and there aren’t any figures like Randall Grahm speaking articulately of terroir. Progressive producer as celebrity is a very new concept and anyone progressive of yore has been doomed to be ahead of their time. Arroyo wasn’t heralded until decades later and sadly after his death.

Explaining rum can be heavy on the science, especially if we haven’t whittled down the discourse. Of course there is considerable science in the production of any spirit, but rum science is different. For other spirits the science is framed within the confines of production laws, while in rum, anything goes so the science multiplies quickly. Bourbon has one or two templates for production, rum has quite a few and that is why it can tell so many stories. The potential to tell so many stories with rum puts it closer to wine than any other spirit.

These comparative issues make it really hard to learn more about rum. Some rums are made straight forwardly like some batch pot still Bourbons with simple fraction recycling programs. The complete volume of product is aged in barrels just like a Bourbon and when it evaporates it is gone just like Bourbon. When it is bottled it can actually be enjoyed as a single barrel expression with nothing but light filtration and water. This is where the “straight” that we take for granted comes in. For rum to follow nothing but those rules sounds kind of lame to me.

I adore whiskies and brandies made in the classic straight template, but I’m a progressive and often I want something more. It is also not the most efficient and rum production is made in dizzying quantities with global responsibilities connoisseurs can’t seem to grasp. Rum in most cases (but that is changing) is a salvage product so there is a big responsibility to make an affordable product because price moves it more than anything else. More molasses is always piling up. So much of the literature from even the 19th century mentions how on the verge of not viable the sugar cane and rum industry was. If producers were stuck processing staggering volumes under the constraints of a single template consumers could wrap their heads around, there would be problems.

Fierce competition as a commodity and pressure as a salvage product, which has to keep moving, has shaped the logistics of production at various points. Rum producers have basically ended up in scenarios that other spirits producers would never face. A big one is evaporation due to typically being in the tropics. Many islands that were important colonial outposts would ship unaged spirits to Europe to age and avoid costly evaporation while others, typically further south, lacked a welcoming parent and tackled the problem other ways. Before taxes, rum was cheap so a lot of times to keep everything moving on the salvage side, evaporation would just be topped up. This evaporative solera morphed into a classic solera, but that makes it no easier to compare to any other product on the market. The UC Davis algorithm for calculating the average age of solera products does not account for such significant evaporation. This leads to a style of aged product that is hard to wrap your head around, but is delicious. Consumers complain about labels while the products are telling colonial stories we can only access if we read between their words.

For some reason we think of the rum industry as wrought with fraud in manufacturing practices and yet if you study the Rum Pilot Plant or look at the present day World Spirits Conference, the industry is wildly environmentally friendly and energy conscious relative to other large scale industrial processes. They make any new American distillery look like an environmental train wreck. The industry has spectacular responsibilities, both social and environmental, and for the most part it handles them. I don’t want to justify anything, but pressures to adulterate may be pressures to keep product moving during wild swings in consumer tastes. Aspects of the industry are still so slow moving, so antiquated and still stuck in colonial legacies that they cannot turn on a dime. If we interpret the stories correctly, we can put pressure on the industry to change for the positive. Most distilleries are soon to be re-tooled and are set to go post-Kavalan anyhow, and that is something I’ve been meaning to write about in depth.

Another rum template you see a lot of resembles blended scotch whisky. Economical continuous column distilled spirits are blended with small percentages of extra heavy batch pot distilled aged spirit. The pot distilled spirits are a little different than single malts and sometimes they are built like such a brick house they cannot be enjoyed on their own as a single straight expression due to ester contents at levels that would be beyond an acquired taste. Pre Arroyo, there was no category of straight light rum. All light rums were heavier rums blended down with neutral spirits from continuous stills and they were inferior.

Rums made on the blended scotch whisky template have encountered all sorts of quirky economic problems due to political factors such as Reagan and NAFTA, but that era is close to over. Producers did not always bottle their own products for over seas markets and instead mainly sold bulk stocks. Despite the commodity nature of spirits, brands were somehow still important. Consistency was the order of the day and if the client wanted an amount of four year pot still rum for a blend and a producer made too much and now it was aged five year, though it might be more extraordinary, it could just languish in the warehouse. There were also lots of trade restrictions and only so much rum could be sent to Europe so the distilleries were often never producing at capacity, but often slightly over producing relative to what they could export. This led to lots of over aged forgotten rum. Sampling a rare independent bottling will tell you, these forgotten rums could be quite special, but the distilleries had no real protocol for capitalizing on them. Distilleries were often government run or stodgy as hell.

There are many small bottlers currently that seem like their blends are beating the pants off other producers and what they’re really doing is sucking up all those gorgeous odd lots that don’t fit in the high volume commodity-consistency market. As the market for premium rums proves itself, the contracts will expire and producers may bottle formerly speculative premium rums themselves. We fault big producers for being out of touch, but in many cases they may just be waiting for small bottlers to do the high risk dirty work of establishing a premium market.

Many rums take on not so much a Cognac template, which would be double distilled in batch pot stills, but simply Cognac flavor aspirations. An example would be Ron del Barrilitto, a big favorite of mine. Cognac is known for it’s finishing techniques. Caramel is carefully added because re-used barrels do not contribute enough color to converge with the aromas. Boisé, or tannic extracts, are often added because the aroma can be so forceful in one direction that it needs contrast in another to not seem flabby. Sugar is also added typically at the limits of 2% by volume which is 31.56 g/L and as a flavor enhancer it changes the threshold of perception of aromas, amplifying them. These aspirations are much different and much more noble than masking inferior alcohol and appealing to low brow consumers.

The rums of a few producers have an extra technique in their arsenal that has been around so long it is absolutely traditional and that is prune juice (sometimes coupled with spices, but not making it a spiced rum). It is a cousin of 19th century pineapple rum where pineapple juice was added to synthesize the character of mellowed rum. There were no secrets about pineapple rum and it was openly consumed and revered. Prune additive is barely secret. Compounded well, they’re wildly delicious and tell a story of ingenuity, pragmatism, inherited definitions of luxury, and colonial heritage. García Márquez would surely endorse them for the stories they tell.

A progressive belief I have is that aromas in the context of wine & spirits are often illusions or hallucinations and neuroscience is starting to back this up. We don’t describe a wine or spirit itself, but rather our own recollections when we try to describe it. This has tremendous implications for understandings of the terroir concept. We can only bond with a land as expressed through a wine or spirit if we have spent time bonding with other lands. Sensory fragments come at us through aromas tied to color, gustatory and haptic sensations, et al., and we complete them with our recollections (of other lands). Caramel, boisé, and sugar are all ways the land, the producer, and the imbiber sing a song together. In the finest lands there will be three singers.

Among the earliest stories of rum ever is that of caramel color. I’m failing at finding the citation I’m looking for, but basically rum was sold at a price to some imbibers, the same rum was colored with caramel and sold to the same imbibers who gladly paid more. Aromas are bound to color and they should always be partnered with a color that makes them perceived to be the most extraordinary (sometimes this is crystal clarity!). Choosing natural color is the same as coloring, except you decided it was already colored where you wanted it to be. Debates over caramel color put symbolism over sensation in spirits appreciation and takes for granted how flavor is perceived. Just like many connoisseurs do not understand caramel color, not enough produces do either, and many fail to end up with a color systematically tried to be the most extraordinary. On the other hand, many spirits nail it perfectly. The extraordinary is tied to frequency of occurrence and many naturally colored rums stand out at the moment because their frequency of occurrence is currently low.

Rums don’t exactly get reformulated to be cheaper to produce, what happens first is that we drink them all and there is a void to fill. Often rums that catch on and see surges in demand, like Ron Zacapa or Pompero Anniversario, were the product of surpluses. Likely, surpluses of aged rums in both Guatemala and Venezuela were so great that the expressions they put out became so good the market could not deny them. Consumers drank them all and started to complain as they tried to fill the void. A Similar phenomenon happened with Bourbon in the 90’s where bottom shelf bottlings were loaded up with well aged stocks, but we eventually drank them all and the glut was gone. Bourbon consumers have been far more understanding of the changes than fair weather rum fans.

Some times a rum jumps islands such as Zaya as pointed out by CocktailWonk (who this post is in part inspired by). Zaya likely tells a story no one bothers to really translate, but Zaya isn’t supposed to spell it out. Spirits are inadvertently like poetry or painting and the poet is cryptic and ambiguous making you work to find meaning. Zaya was no doubt the product of serious wheelings and dealings as well as a dream of bringing the Caribbean jungle to some opera somewhere. I have a feeling there was a Fitzcarraldo in Zaya and we all missed it. We drank it all and yet it was still ahead of it’s time.

Consumers are asking producers to be the connoisseur for them and that is not how it works, Hemingway would side with me. If anyone needs a template I recommend consulting Hannum and Bloomberg’s Brandies & Liqueurs of the World, (1976). I never wrote about it, but I tracked down Hurst Hannum a few years ago for lunch and was regaled with tales of touring Europe in an MG roadster convertible visiting producers who hadn’t seen a writer since André Simon, and documenting them. They flipped the roadster in front of a Cognac chateau and Gatsby style, the owner righted their car, helped them repair it, and hosted them for a few days. The rum world had Hugh Barty-King and Anton Massel in 1983, but even with the spirits renaissance and distilleries hosting spirits professionals left and right, no truly brilliant connoisseurial investigators have come since.

The last distilling template is the super fractionated template. Spirit from a continuous column stills is taken uncut except for the fusel oil reduced. This is transferred to a batch column still where it is redistilled as slow as possible with high reflux and separated into as few as five fractions. The first fraction is recycled or possibly re-fermented to have it’s aldehydes reduced into ethanol by yeasts (Guymon’s technique) while the remaining fractions go on to become rum. The last fractions, already low in fusel oil, are distilled further along than in the straight Bourbon template to accumulate rum oil. The same continuous still used to produce near neutral spirits can be briefly retooled to participate in this process and that is why Ron del Barrilito can buy un-rectified stocks from other producers. Specialty ferments can likely be lined up in the continuum.

Percentages of each fraction get blended together to be light rum. The remainder of each fraction is not entirely aged as heavy rum. The middle fractions are mostly water and ethanol (congener free) so they do not benefit from aging. The scraps that go into the barrel age faster because there is less unageable ethanol and water taking up space in the barrel. These techniques are practiced with infinite options and it is very hard to say to what degree any specific producers use them.

Super fractionated distilling is practiced in tandem with deeply involved biological control over fermentation. Fermentations are inoculated with more than just a single pure colony of yeast in some cases as well as selected bacterial strains. Unless the heaviest possible rum is desired, bacteria in spontaneous fermentations can eat up sugar, reducing potential alcohol. Arroyo developed methods of inoculating bacteria at later stages in fermentation so a desired yield of alcohol could be produced before bacteria started to metabolize hard to ferment residual sugar or other compounds.

Pursuing economy is not about being cheap, it is mainly about environmental responsibility and each percentage point of potential ethanol squandered is an environmental burden with intense water usage and significant effluent to dispose of and this was even a concern in the 19th century. Spirit production priorities differ from that of wine and the comparative philosophies are something I’ve wanted to tackle in depth for quite some time (there is a lot of literature left on my list to collect).

Large distilleries have economies of scale that allow for scheduling of exotic fermentations because they have shifts running around the clock. Bacteria may be inoculated, then like a bun in the oven, the wash will have to be distilled so many hours later to not spoil. Ron del Barillito may have fermentation dreams that are beyond their ability to staff their own distillery and that is why they purchase stocks from an around-the-clock operation. That is sadly not the sexiest fact to explain to a consumer.

Small distilleries have logistical problems trying to emulate larger operations, but an option that I’m not sure how widely it is used is immobilized cell technology where bacteria or yeast are immobilized in alginate beads. Significant biomass of yeast or bacteria can be put into a fermentation then completely removed using a wire cage arresting the activity of the beads. Specialty fermentations can be designed that fit into the scheduling logistics of a small distillery and that is something I aim to explore.

Progressive ideas, that started with Rafael Arroyo, push rum into the territory of ingestible perfumes and that is the pinnacle of being able to cement and retrieve a memory. Super fractionated aging may even render the techniques of the Lost Spirits distillery unnecessary and irrelevant. Pure culture multiple inoculation biotechnology and super fractioning techniques are in no way cheating and simply represent visionary dreams and possibilities just like those of the perfumer. The contents are hard to label, but the aims are pure.

Many rum production techniques can be portrayed as modern, progressive, and visionary and that is my reading of so many rums, but somehow it gets lost when we are multiple generations removed from Arroyo and other major thinkers. Producers themselves end up in a bubble and lose the ability to contextualize their own product. If you can’t contextualize it you can’t meet the emerging demands of a curious premium consumer. Spirit producers probably need to relearn their own industry’s history.

Hopefully I’ve succeeding in portraying that rums can reflect the social aspects of terroir better than even wine. They are capable of even being pushed out of their home lands as seen with Bacardi in Cuba and again with Zaya. As society and political climate changes so too does rum. When we think rum is unregulated and unconstrained by production laws that is far from the truth.

Now that a lot of trade barriers have come down for rum, one of the most recent regulations to shape it concerns the toxic congener ethyl carbamate. Producers globally are supposed to reduce their levels of ethyl carbamate in spirits and scotch producers have already made strides so great no one noticed. That sounds nice, but compliance domestically is voluntary and many domestic producers have no clue what the hell it even is. When a producer wants to cross borders they must comply and that means new capital investments which are hard to finance. The chemical compound becomes a trade barrier and keeps some producers out of big markets like the U.S.

Instead of successfully becoming a barrier and slowing trade, ethyl carbamate has caused governments like Brazil to reinvest in agricultural research to better control production in general. Ethyl carbamate is reduced by using stills that are strategic combinations of copper and stainless steel (typically a stainless condenser) because it is the product of complex copper reactions. Reflections on technique across the board spurred by ethyl carbamate have improved spirits quality in multiple areas.

Every spirit tells a story of course, but counter intuitively the story a rum tells is less contrived. Scotch and Bourbon producers apply startling science and marketing acumen to lock their spirits in time, dodging risk while rums float around and are free to reflect so much.

We need to get away from an obsession with truth in labeling in all spirit categories. Navigating spirits and wine is a large part of the fun. The challenges are why we can find value. We also live in a new era where photos can be taken of labels then immediately scanned on a smart phone and any dirty secret revealed. Templeton and any other MGP whiskey did nothing but continue the traditional marketing of spirits that paralleled traditional production. Any additional information a consumer needed to be “protected” is a label snapshot away. The government is on top of protecting you from toxic congeners like ethyl carbamate and in turn overly affordable imports from underdeveloped countries.

I hope I’ve done some justice explaining production templates and that they may clarify the tricky proposition of creating labels. Rums made as straight Bourbons will be easier to understand, but they will not be as extraordinary as other more elaborate templates. There is nothing finer than rum as we make it. If rums were labeled as they were made, they’d need bigger labels. The multi dimensionality would not make them easy to compare and in the end we’d just take Anthony Bourdain’s advice and submit while soaking up a story.


Amateur Spirits Analsyis

The home hydrometer test is great place to begin for investigating spirit finishing techniques, especially because it does not require you to sacrifice any samples such as in obscuration tests that distillers are often required to perform to see to what extent soluble solids from barrels obscure the true taxable ethanol of a spirit. For whiskey, in most cases, the barrel obscures 0.2 percentage points. What I often advocate is sacrificing a small sample to a food dehydrator. This could be 50 mL’s measured with a pycnometer. It can be weighed before and after dehydration so see how much non-volatile fraction there is which will be mainly sugar. Often, if there is something like glycerol it will not crystalize and can be seen as a little oil slick. Rum connoisseurs will be surprised to find that they will probably very rarely ever seen glycerol. I’ve only ever found it in gins. Now that you’ve destroyed a sample worth only a few dollars, you can carefully reconstitute it with neutral spirits like vodka to see what the non-volatile fraction tastes like with no volatile fraction to bias it. Often there will be aroma because the bassy notes contributed by a barrel are barely volatile as well as possibly notes contributed by sherry barrels.

A limitation of the hydrometer that comes up from time to time is that if the spirit was bottled under proof accidentally, it will not be caught and sugar will probably be attributed to the culprit whereas dehydration will give different results. I’ve only seen under advertised proof spirits from very new distilleries that have not mastered blending yet.

If curiosity is burning or if you are in a position where it is worth your while to do competitor analysis, you can sacrifice a larger sample to the Micko test which was used more than a century ago to look at adulterated Jamaican rums. Take a genuine sample and the suspected adulterated sample and dilute them to the same proof and volume. Now distill them with identical amounts of very high reflux and distillation times on small scale laboratory glassware. Collect at least five identical fractions. Similar aromas across both samples should be in the same fractions while an adulterant, like orange oil, will stick out like a sore thumb now that it has been concentrated.

The same Micko test can teach new producers the art of cutting and blending. You compare your own product to a role model so you can see more easily how your most volatile and least volatile fractions compare. Many new distillers and new blenders would greatly benefit from this affordable concept. Formal elaborations of the Micko test exist associated with other specific scientists and I aim to touch upon them in depth some day (Arroyo fully elaborated the test).

I have long thought many rums contained artificial vanillin or it was just a product of a style of aging that I really didn’t enjoy (or fully understand), sort of like wines that see too much new oak. Old UC Davis texts describe methods of treating barrel staves with pure oxygen to maximize lignification and if that is the case, all the aromas come from traditional ingredients and traditional chemical processes though sped up in very similar methods to what Lost Spirits is doing. I always thought if manipulation of staves was the case, I would have found a research paper on it outside of the UC Davis work.

I had heard anecdotally long ago that when you buy a sherry, port or sauternes cask, there is an amount of wine sloshing around in it to prevent bacterial growth. Producers would not drain the residual wine but just fill on top of it and who could blame them. Hell, I’d hold it against them if they didn’t. We may be given an illusion that the wine character is merely soaked into the staves, but that may not be the case. These small stories that rums can tell are never in any official literature because it is quasi legal and is only a secret that the barrel men and the drinker are in on.

Some of the distilleries in the Caribbean are among the very largest in the world, but that does not mean over distillation as suggested by CocktailWonk is a problem. When we say distillation at a high proof strips congenerics that makes the assumption that we are making cuts during batch distillation or taking off side streams during continuous distillation. In the Arroyo system of simultaneously making light and heavy spirits, washes are first stripped on a continuous still, cuts are not taken but fusel oil is reduced. That uncut distillate is rectified in batch column stills and distilled extremely slow under very high levels of reflux to divide the spirit into multiple fractions. Percentages of each of those fractions become the straight light rum and then the majority of the rest gets aged in barrels for extended times. Aged product is then blended down with either unique stocks, light rum, or neutral spirits to bring congener thresholds to where they need to be.

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