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#5
This ferment is important because it helps us capture the full range of curious behavior possible. Fermentation lasted roughly four weeks and had a TA that was below what Kervegant called grand arôme at 11 g/L, and while all the other ferments dropped in pH and rose in TA, this ferment rose in pH and staid the same in TA! It also exhibited the curious behavior of dropping in pH when water was added to perform a TA. This pH drop upon watering may be attributed to ester breakage, but it is hard to say conclusively. A colleague did mention, he has observed similar observations in making sour beers and suspected yeast autolysis could be at play, and the mechanism for that pH change may be amino acids bleeding back into the ferment.
6/27 pH 4.2 TA 11.18 F# 359 (missing original gravity and pitching data.)
7/22 SG 1.040 and nice activity at the top
7/26 pH 4.38 TA 11.10 F# 276 final SG 1.032
This produced great birectifier fraction #5 aroma, but there does not seem to be any significant column clouding like the previous ferment.
I’ve sat on this post for a week or so and talked over related ideas with Cory. What was observed in terms of pH and TA may be a desirable if not ideal outcome and may be related to the starting volatile acidity to which we’re beginning to gain hard numbers. Lots of ideas are floating around but we need more observations.
Fraction 1: Appreciable ethyl acetate concentrated to the point of non-culinary aroma, but not a monster by any means.
Fraction 2: Diminutive version of fraction 1.
Fraction 3: Extremely neutral as expected.
Fraction 4: Definite presence of fusel oil, but I’d call this extremely light. It is actually surprising.
Fraction 5: Very estery bouquet. Cloudy but not overwhelmingly. Not really detecting the rum oil character I sense in fraction 6 which is odd. Not acrid on the palate. Large droplet on the surface with many other small droplets. Tasting this undiluted later, I definitely detected rum oil character.
Fraction 6: Slight rum oil aroma. Also slight cheesy aroma. Very faint gustatory acidity. Many easily noticeable small droplets on the surface.
Fraction 7: Possibly more acidity than fraction 8 but not much character here. Many easily noticeable small droplets on the surface.
Fraction 8: Almost a faint butyric aroma, but hard to detect. Not much acidity.
Stillage: Extremely tart. pH 4.14, TA 1.25 (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.
What is interesting is if you go back to the previous ferment and compare the numbers. Substantial differences with 1/3 the acidity while still a very strong fraction 5 worth being proud of. Keep in mind, stillage is just easy to measure when sample volumes are particularly low and you need to save your birectifier fractions for other purposes. I may just start doing fractions 6,7,8 as a batch.