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This is part of the will it even ferment series and I regret the gaps in record keeping. I did not believe the results would be so interesting. This appears to be a 19 day ferment with very significant ΔTA, but it is hard to say if it is volatile acidity or simply non-volatile organic acids like lactic and succinic. I’m hoping to introduce the RD80 vintner’s Cash still to measure VA and gain some insights. I did not measure the final formal number because I ran out, but this time bought a gallon! Could the high increase in TA, have anything to do with the highest formol number I’ve seen so far?
These exercises have really morphed because of the results, so record keeping and data points will have to evolve. One thing I’m curious about is free butyric acid or not, detected organoleptically. I’m also curious about the transformation of acetic acid into other long chain acids and esters. Dunder reuse is also a concern. As final gravity has risen with reuse, starting gravity may have to increase. The significant change in acidity calls for better notes on the dunder I input. This ferment may be from baker’s molasses I had around, but currently, I’m exclusively using Arroyo style prepped thick mash which is 55 brix. This is limed to pH 6.2, heated to 80C, and centrifuged. The heat in this case (non-pure culture) may only be to help precipitate impurities which often come out as heavy as peanut butter.
The lack of rum oil here is curious, especially when considering all the acid generated during the ferment. I’m wondering if this case study represent the anecdotes where two rums can give extremely similar numbers via GCMS, but one can be considered far more valuable. Rum oil is not detected by the typical GCMS…
7/1 pH 4.13 TA 13.33 F#445 [SG likely 1.085]
7/20 pH 3.97 TA 20.56 F#not taken SG 1.035 [liter volumetric flask]
Fraction 1: Slight fruity but not overly concentrated. No intense non culinary aromas.
Fraction 2: Diminutive version of fraction 1. Nothing out of the ordinary.
Fraction 3: Neutral as expected.
Fraction 4: Definite fusel oil aroma, maybe slightly higher than other ferments of this series?
Fraction 5: Cloudy, but no separating emulsion. Definitely estery, but no distinct rum oil. Not acrid on the palate. Slight gustatory acidity. I remember the column becoming incredibly cloudy when this fraction arrived, to a degree I’ve only seen once or twice. The way this is estery without rum oil is reminding me more of a fruit eau-de-vie fraction five rather than rum! I suspect the column clouding was due to the significant longer chain volatile acids that would appear in the following fractions.
Fraction 6: Tart on the palate. Every so faintly cheesy aroma. No obvious free butyric acid. I sense the tartness increases across 6,7,8.
Fraction 7: Tart on the palate. Every so faintly cheesy aroma. No obvious free butyric acid.
Fraction 8: Quite tart on the palate. Every so faintly cheesy aroma. No obvious free butyric acid.
Stillage: Extremely tart. pH 3.22, TA 4.06 (This was a 10 ml analyte, but the original volume is unknown because of rinsing water added to the original charge.) No obvious butyric smell.