Recently I’ve had the opportunity to try out a good selection of extremely high ester rums. From unaged Hampden Estate DOK at 85 percent ABV, to Long Pond TECC, Savanna HERR, and several others, I’ve tasted enough samples to seriously contemplate the extremely high ester rum world.

As much as anybody else, I once craved the high ester experience, plotting the day I’d have my own sample of Hampden’s DOK at home, available at a moment’s notice. Today, I’m thrilled to have two very different DOK expressions in my rum library. Yes, I’m unabashedly a high hogo Jamaican rum dunderhead.

But here’s the thing… What you’re anticipating with these extreme funk boms is very likely not how they register once they hit your tongue. When you read about Jamaican “Continental” rums at 1600 g/hL AA being intended for blending in small amounts, you can take that to the bank. They absolutely aren’t intended for run-of-the mill consumption, neither then, nor now.

I get it. We crave funk, the more the better. But here’s the thing – Esters aren’t additive across wide ranges. How our sensory systems perceive esters and volatile compounds isn’t linear. In fact, a given ester can smell like one thing at one intensity, and something entirely different at another level. The amazing fruity notes give way to something much more harsh, and possibly unpleasant. In my look at the Savanna HERR, I had this to say:

…an almost chemical solvent character that’s impossible to describe: Neither fish, nor fowl, nor anything else familiar. In time, a bit of mint strolls by in the background. A good while longer, as your taste buds and nasal passages finally stagger back to life, along comes a blast of … wait for it… Brach’s strawberry flavored hard candy.

Consuming super high ester rums is certainly an interesting experience. By all means, try it if you have the opportunity. But be aware that it might not be the transcendent sipper you’re imaging it to be.

I’ve been mulling how to write about this for a while. Meanwhile, Foursquare’s Richard Seale recently posted an extremely informative Facebook post on this topic, and he’s graciously allowed me to share it here.

A WORD about HIGH ESTER (Flavoured) Rums – the Cousins Process

(By Richard Seale)

During my impromptu meeting with Carsten E. Vlierboom of E&A Scheer recently in Miami, I expressed dismay at the recent independent bottling of the 1,600 ester DOK marque. Matt Pietrek who has been researching Jamaica rum extensively of recent has also in his quiet manner explained that these marques are not for drinking.

In the 19th century, Jamaica Rum was exported in great quantities to the UK and the European continent, Germany in particular. In 1889 Germany dramatically increased the import duty on Jamaican Rum and severely reduced this trade. The clever Jamaicans responded by created a class of “Flavoured Rum” (meaning for flavouring) which could create a blended rum to compete against the local spirits (subject only to nominal excise taxes).

McFarlane (1947) classified Jamaica Rum into four categories – common clean, Plummer, Wedderburn and flavoured. The first three were up to 300 esters (g/hl AA). The flavoured category was 700 to 1,600. Now by esters, we mean ethyl acetate, the simplest of all esters. The others are not included in the count.

At the 1908 Royal Commission on Potable Spirits, J C Nolan, special commissioner of the Jamaican Government to the UK, made it quite clear the purpose of the flavoured rums.

“It is a flavouring essence. It is not a self rum”

“No, you could not drink it as a self rum”

In theory you can make these high ester rums in the normal way by extending the fermentation long enough. The longer the fermentation the more acids by bacteria are produced. The acids react with the alcohol to produce the esters. More acids, more esters. However, this starts to get very impractical and this will leave a very poor yield of alcohol in the ‘wash’ to distill.

To solve this problem, the brilliant Jamaican chemist HH Cousins developed a process to boost the ester count in rums in a more economical way.

The ‘lees’ in the retort at the end of distillation retains a considerable amount of the acids from the fermentation. Volatile enough to make it to (and concentrate in) the retort, not volatile enough to make it to the rum. The acids are recovered by adding lime (calcium oxide) to the lees to produce the calcium salts of the acids. This concentrated acid mixture after precipitation of calcium sulphate (by adding sulphuric acid) is added to high strength rum (i.e. lots of alcohol) and placed in the high wines retort where the esterification process (alcohol + acid) takes place. The resulting distillate is now supercharged with esters – up to 7,000 – and this distillate is used to ‘top up’ the rums produced in the normal way to reach the levels such as DOK at 1,600.

Gentlemen bottlers please, the Jamaicans are laughing at you, Mr. Nolan and the Hon. HH Cousins are spinning in their grave. DOK and similar marques are flavouring essences, not for drinking. They are produced by a process adjunct to distillation.

Pungency is not quality.

I know it has become fashionable in certain circles to marvel at flavour, any flavour. The burnt tyres and excess fusel oil of the likes of Caroni for example (bad fermentation and bad distillation produces this).

It would well be advised to listen to the advice of HH Cousins:

“An increase in the ethyl acetate content of a rum…, if not supported by an increase in the other esters in suitable proportion will not add to its intrinsic value.”

“…there are certain “marks of rum (and among then some of stout body and attractive quality) which are as low as 100 esters”

The measure of ethyl acetate was as important to the regulation and control of Jamaican Rum as was a measure of alcoholic strength. It was not a mark of quality.

And it is well worth noting that esters are formed during ageing. And these esters are the more complex esters with very attractive aromas. For most aged spirits, these are the most important contributors to the flavour.

Jamaican Rums are certainly very remarkable for their ester content. A tradition we can still enjoy today. It is wise though to understand the differences.