Birectifier Analysis of Foursquare Single Barbados Rum

[Foursquare single Barbados rum 2 y.o.]

64% ABV Barrel proof
Unchillfiltered, sugar free, natural colour
100% Pot Still Distillation
Distilled 2013, bottled 2015
Aged in the tropics / Angel’s share > 15%

What an absolutely wonderful rum. The bottling is a collaboration between Foursquare and Velier to celebrate a double retort pot still built by Green Engineering and Forsyths.

We get some wonderful disclosures about the rum, but the big one I’m curious about but not seeing is that the yeast type, duration, and the Δ acidity of the fermentation (how much acid was produced by bacteria). This rum was not overly estery, but shows remarkable persistence due to rum oil. I was very excited to see the droplets in fraction 5 described by Rafael Arroyo in Studies On Rum. Could this be what was historically called a common clean rum, but made on a big pot still?

Besides rum oil, this rum exhibits a few of Arroyo’s other key principles. It demonstrates an elegant ratio between lower boiling point esters to higher boiling point esters, making it never seem heady like Jamaican overproof rums. It also has an elegant ratio of esters to fusel oil. It quite evidently has a well balanced chemical composition.

However, it is 64% ABV. Did they avoiding the challenge of getting it down to drinking proof? This is an open question in understanding the category of pure single rums (which I think can be watered). My theory of the droplets is that they are the most insoluble and diffusive portion of whatever makes up rum oil (rose ketones). If these compounds break (come out of solution) upon watering before being barreled, they escape with the angel’s share. If they break in your glass while a little water cuts the rum to drinking proof before consumption, they escape to your nostrils for glorious frontal olfaction. Could this be the theory behind leaving rums barrel proof? Preserving as much of the rarest character possible?

This rum is a great achievement and new American producers would be wise to study it.

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Fraction 1: Concentrated to point of non-culinary aromas, but not too significantly concentrated. This is making me think I should create a comparison against Rum Fire.

Fraction 2: Not too concentrated. No non-culinary aromas. Feels lighter than I expected.

Fraction 3: Fairly neutral. I almost think I’m detecting something pleasant, but I’m not sure.

Fraction 4: Definite presence of fusel oil. Not quite a wraith. Likely just where it should be.

Fraction 5: Radiant and lovely. There was a point I accidentally left the watch glass cover off, and was typing away. I knew because the smell started to fill the room. This fraction was slightly cloudy, but produced no pronounced louche like other full bodied rums. I would say this is not overly estery. There is no acridness on the palate associated with pronounced long chain esters. Something unique to this fraction which I’ve never observed before is rum oil associated droplets described by Arroyo in Studies On Rum. I’ve covered numerous case studies positive for rum oil, but none with distinct droplets. I’m wondering if this has anything to do with the pure single rum concept. This rum was barrel proof so there was no potential for aroma breakage by watering the spirit. After a short while, it seems like the droplets evaporated, yet the rum oil aroma persists. A big question is: how does this differ from Rum Fire?, which had no distinct droplets unless they were mixed in with a louche.

Fraction 6: Faint rum oil aroma? No extra detectable character. No significant detectable gustatory acidity. This fraction featured an insoluble precipitate which is visible floating in the fraction at the right hand side of the very top photo. This has been seen in many other spirits, but the composition is unknown to me. Is it a complete ester or only a fatty acid?

Fraction 7: Pleasant, no inharmonious character. No significant detectable gustatory acidity.

Fraction 8: Something pleasant I can’t quite characterize. No significant detectable gustatory acidity.

Stillage: No detectable gustatory acidity. Detectable tufo.