Birectifier Analysis of a Novel Model Retort Still Rum

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The project at hand is distilling a ferment on a glass model of a double retort pot still. The wash is driven off a 3 liter laboratory heating mantle and charged to two liters. A precision heating controller (borrowed from my birectifier) provides pacing and times under heat that stretch upwards of four hours allowing a model distilling run to somewhat replicate the operation of a full scale design.

This post is a little bit preliminary because I don’t yet have an ideal fraction recycling system. I also needed to collect more data on parameters for retort operation but have found what I think I need in the 1944 and 1947 issues of the J.A.S.T. journal. I blew the glass swan necks myself to join the retorts and need to go back and attach thermometer ports. I also need to blow & calibrate some glass “spirit bubbles” to help make cuts because these volumes are too small to float a hydrometer.

One of the biggest benefits of this setup is that it operates very predictably. If you need to run it for four hours, you can simply set a timer, walk away and it will be where you left it. I previously had no experience with this still design. The big open questions is whether it can provide meaningful esterification during distillation relative to esterification in the ferment as a biotransformation.

This 80% ABV model rum was quite estery and probably what a lot of people are seeking. The main features of the wash were being driven by a fission yeast and featuring cane trash (which I have already proven bumps aroma).

The residue of the low wines retort was very stale in character but tart like lemonade with nearly zero ethanol. The residue of the high wines was not properly exhausted of ethanol and had a beautiful estery character that I did not expect for its low ABV. If I was operating correctly, I could have harnessed more of this character, properly moving it to my collected high & low wines tails fractions.

One feature of this retort setup is that it has a heating mantle and controller for each retort. However, so far, I have not needed to use any of them and have powered everything off the wash still. The Jamaican distillers of the 1940’s appeared to only have been using their retort heaters for pre-heating to reduce total process time because they were trying to fit three cycles into a day. They still had to run their wash pot long enough to exhaust its ethanol. What I thought was that eventually the wash pot would be turned off & closed off while the second or third retort would continue to be heated to exhaust the ethanol. So far that does not appear to be the case.

A lot could be expanded upon here if I can get sufficiently setup to take more measurements. I would like to look more at the movement of acids between the wash pot, retorts, and ultimately collected fractions and residues. Some old literature claims that retort residues are run to the dirty/muck cisterns and that is quite interesting. That could mean you fill those cisterns with antagonistic acids requiring a lot of liming or also that any rum oil/rose ketones that stayed in your retort residues may be dumped into a muck cistern for recycling rather than being produced there as a biotransformation. Another note in the literature is that retorts could contain as much as 1% acidity or 10.0 g/L of VA. Are those numbers the result of natural operation or use of the high ester process?

Something to note about the birectifier fractioning is that I had a recurrence of surface tension issues in the later fractions (6,7,8) and actually stopped collecting them. This is likely due to certain long chain material that dramatically reduces surface tension which probably came from cane trash usage. None of this is bad, but my analysis method was not prepared for it. Condensate stops dripping neatly at the point of the “take off”—drip tip and starts sputtering where it cannot seem to go in the narrow volumetric flask. My solution was to machine up a prosthetic spout from teflon to slip over the current condenser. In the future, I may just blow a different type of condenser and pull the take off to a shape that better collects the erratic droplets.


Fraction 1: Concentrated but not to the point of gluey non-culinary aroma; not overly concentrated in ethyl acetate.

Fraction 2: Diminutive version of fraction 1 as expected.

Fraction 3: Fairly neutral as expected.

Fraction 4: Penetrating estery aroma overshadows the fusel oil. My sense is that this clearly has the below average fusel oil content expected by a fission yeast. I remember ending this fraction a few ml. early because the estery aroma was becoming so pronounced. My thought is the aroma arrived early due to its nature and concentration rather than other variables such as heating scheme caused it to come earlier. It smells lovely despite being the fraction where 75% of the fusel oil is expected to be.

Fraction 5: Estery but not massive; broader and less penetrating than what is noticed in fraction 4. Louched and covered in visible droplets, but no separated emulsion. No clear sign of ethyl-butrate.

(Fraction 6,7,8 not collected and form part of the stillage due to surface tension issues.)

Stillage: Faint butyric odor. Slight staleness. Very low gustatory acidity. Often these are tart like lemonade. No doubt due to the high ABV the distillate was collected at.

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