Birectifier Analysis of a Continuous Column Fission Yeast Rum

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Two exciting rums crossed my desk from Jace Marti at Black Frost Distilling in Minnesota. These were produced with a modified Arroyo process featuring a pure culture fission yeast and long duration open top fermentation in wooden vats. The 1000 gallon wash is composed of molasses and dunder. Distillation is via continuous column still with a doubler and typically taken off at 61%.

Black Frost has also had notable success producing grain spirits featuring fission yeasts.

The unaged spirit is not conventionally heavy in the Jamaican sense but has a distinctive character. Birectifier analysis threw me for a loop because nothing in the spirit says it is obviously estery, but it’s fraction 5 was deeply louched with strong persistence. This possibly indicates a concentrated but narrow in type band of esters. It is almost like some sort of advanced light rum. Is this what is possible when you do not have to cut away excessive fusel oil? It possesses the framework for radiance, but so far, before élevage in the barrel, has not much to illuminate. Radiance in the unaged spirit, however, shows well in cocktails where you can add your own round fruit character to flatter it. I proofed down a small amount and was making distinctive periodistas.

Jace described experiencing the phenomena where if the top ferment persisted for the whole duration (they are notorious for dropping), yeast produced what may match 19th century descriptions of “rum fat” associated with a top ferment. Longer chain molecules are produced which dramatically change surface tension and you even have to run the continuous column still slower to minimize foaming. Fission yeasts, at times, under narrow conditions that are not fully elucidated, may be capable of behavior we typically project onto bacteria such as the creation of significant volatile fatty acids. Jace may be harnessing the positive aroma potential of this phenomenon while dodging the potential negative aspects like overly fatty distillates described as flaw in Le Cognac.

The aged spirit I was given a sample of had spend only 11 months in the barrel. I loved it! I was getting flickering memories of the original Plantation offerings of the early 2000’s that inspired me to pursue rum well before I knew who Arroyo was. In the aged spirit, the radiance had something to latch onto and perhaps the spirit even fattened. There was a clear sensation of distinctive rumminess. Quite possibly, this spirit was exemplifying Arroyo’s idea that spirits with rum oil and other proportions he favored would mature faster. Ethyl acetate would no doubt increase during time in barrel and the rum would fill out even further.

These rums may even follow the ideal described by Kervegant where spirits age to completion. It may see minimal watering before entering the barrel and then slowly lose alcohol to the angel’s share until roughly 50% ABV where it is complete and mature requiring no additional dilution.

Jace’s aged rum has the makings of a daily drinker (which for me has typically been R.L. Seale 10 year). I went from sipping to sours, to brown & down cocktails with none of the complaints I have from other molasses rums where they generate stuck flavors in one or the other. Are we currently experiencing the closest expression we can get to the lost heavy rums of the 1940’s Rum Pilot Plant? Is this the makings of a Tiki great? (Yes!)

These rums are exciting, inspiring numerous texts from the vat room:


Fraction 1: Not overly concentrated. Something I don’t understand seems to skew its tone. Possibly more than just ethyl acetate? Would iso amyl acetate show here?

Fraction 2: Fairly neutral. More so than I expected.

Fraction 3: Extremely neutral as expected.

Fraction 4: Detectable fusel oil, but inline with a below average level expected from a fission yeast.

Fraction 5: Visibly louched and covered with droplets. Obviously estery, but almost seeming from a narrow concentrated band. Under the esters you get flickers of a damascenone like rum oil note. Radiance and concentration but not breadth? I let this fraction sit under a watch glass for well over a week. After significant time, concentrated esters blew off and damascenone became extremely obvious.

Fraction 6: Very little carryover of esters and a faint menthe character is evident; in general fairly neutral.

Fraction 7: Faint persistent radiant aroma. no obvious gustatory acidity; in general very neutral

Fraction 8: Faint persistent radiant aroma. no obvious gustatory acidity; in general very neutral

Stillage: Fairly neutral with detectable gustatory acidity; probably worth titrating. Perhaps this inherent acidity gives the spirit a head start in maturation? We know in Bourbon research papers, maturation does not typically take off until the pH of the spirit drops significantly.

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