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I’ve been keeping only about two ferments going at a time because I’m working on other projects (and making major progress on the important one.) Within this small amount of action, what I’ve been exploring is incorporating cane trash into ferments. This is incorporated to what I typically refer to as my common clean rum format. The fission yeasts for this ferment were grown on a sterilized broth taken from my cane trash cistern that is dominated by an epiphytic yeast from the cane. The trash is covered with water and an amount of acetic acid. The resulting broth smells vaguely like cooked corn which could possibly be from the cane albumin/protein that was hyped by 19th century authors like Wray. I had spectacular yeast growth with an incredibly simple media. The trash broth may have provided nutrients that the yeast particularly liked. The small amount of vegetable protein in the cane may have also started breaking down into amino acids which led to distinct esterification when metabolized by yeast.
I won’t go into all the details of my common clean format and quite often the results are a charming light rum and not remotely a heavy rum unless muck is added. What I will mention is that I grow an abnormally large starter and this is fairly easy because of the unique properties of the growth media. There is a stage where media is only pasteurized as opposed to sterilized. I also start growing on panella even though the ferment is ultimately a molasses ferment. The bulk of the fermentable sugars are from an Arroyo style thick mash adjusted to pH 6.2 that is incrementally dosed (I am exploring integrating cane trash to the 55 brix thick mash). The pH starts in the 4’s, and over the course of the ferment, averages up. A percent of dunder is also added. This misses much of the magic of Arroyo’s high pH process but results in a low risk, easy to execute, very high ABV wash of fairly high quality that ferments over roughly 6 days. It is a platform to build other complications upon like efficient use of muck or an aroma producing mildew yeast.
This rum was no blockbuster by my standards, but I do believe it featured a high value aroma bump from the cane trash that needs more exploration. The ferment may have also featured a nice degree of esterification as a biotransformation. The distilling run was only 45 minutes and likely generated little esterification in the still. I think I observed above average ethyl acetate and a fairly strong amount of higher value esters in the 5th fraction despite the ferment not being particularly high in free volatile acids.
I also experienced some unique behavior while fractioning. For starters, much of the high value aroma started early in the 4th fraction despite me being confident I properly dosed 100 ml of absolute alcohol for fractioning. High value aroma, which is quite obvious when it starts, should be mostly confined to the 5th. This could elude to its nature and volatility relative to what you see in other spirits. In the 6th and 7th fractions, I experienced a weird surface tension phenomenon associated longer chain length molecules. The condenser has a “take off” which basically refers to the tube that leaves the condenser. This tube is cut at an angle to create a point liquid is supposed to drip from and precisely enter a narrow 25ml volumetric flask. Well, surface tension aberrations had the droplets bouncing around and not dripping from the designated point. Much spilled over the volumetric flask which I have never experience before. What I think this experience implies is a particular congener contributed by the cane trash. What is further unique is that most of whatever was contributed may have been an ester rather than just a longer chain free volatile acid which often has a sweaty character and is easy to perceive as distinctly sour in the unbuffered distillate. Some of the later fractions in very heavy rums are as tart as lemonade.
[Unique surface tension was resulting in the distillate dripping not from the point but at the back and not make it into the narrow volumetric flask.]
The original spirit was 57.5% (while many commercial producers distill to 70%). Fusel oil was well below average and all liabilities that could influence a tails cut decision are probably only based on free volatile acid. A spirit at 57.5% will mature much quicker than a spirit at 70% and it is probably less of a big deal that it has so much ethyl acetate which will further accumulate during maturation in a barrel.
I could not be certain if this spirit had any degree of the damascenone driven radiance I am chasing. However, it does have a layer of esters I know others are chasing.
In my Rational Bourbon Production —> Heavy Rum post from last year, I mentioned the various categories of esters:
Ethyl acetate (with awareness of ethyl formate from the point of view of bacteria selection and distillation)
Cane derived esters (vesouté)
Yeast body derived esters (Bauer oil esters)
Ethyl butrate (and other special effect esters like ethyl tiglate)
What this ferment likely emphasizes is cane derived esters that typically cannot be developed from molasses alone. These esters cannot power an entire heavy rum but are a component of quality and there may be ways to integrate them into ferments under clean conditions as opposed to their association with open culture ferments.
I cut corners to create a research scale ferment such as adding exogenous acetic acid, but another idea worth pursuing is that all acids need for a ferment, either lactic acid or the spectrum of VA, could come from optimized processing of cane trash.
Fraction 1: Above average presence of ethyl acetate but not to the point of non-culinary aromas. Faintly something else extra.
Fraction 2: Drops off sharply towards neutrality. I almost expected more.
Fraction 3: Neutral but almost something more which may be nothing but the arrival of fusel oil.
Fraction 4: Likely a below average fusel oil content, but significant fraction 5 aroma bled over. I don’t think there were any errors in the 100 ml of absolute alcohol I allocated.
Fraction 5: Cloudy, but not exactly turbid or containing an emulsion. Some insoluble stuff on the surface. Beautiful estery aroma, but nothing overly powerful. Slightly generic and nothing to hint at unique esters or other congeners. No obvious rum oil. The persistence is really nice so you may think their might be a radiant effect, but nothing is obvious.
Fraction 6: Faint ester aroma, not any kind of sweaty VA aroma. No significant gustatory acidity.
Fraction 7: Faint ester aroma, not any kind of sweaty VA aroma. No significant gustatory acidity.
Stillage: I was expecting appreciable acidity but there is nothing significant here.