|pH as a function of time (hrs). Nutrients added at |
roughly 24, and 82hrs.
OG: 1.1080 --> FG: 1.0025
pH 5.60 --> pH 3.56
OG: 1.1080 --> FG: 1.0015
pH 5.33 --> pH 3.56
Both fermentations were held within 1C of 20C (both had peaks of 21C @ 92hrs from pitch, right around the pH stabilizing). Nutrient additions and aeration were determined by gravity reading, not time after pitch.
|Specific gravity as a function of time. Nutrients|
added at roughly 24, and 82hrs; aerated at
roughly 24, 44, 58, 68, and 82hrs.
Nutrients were added at roughly 24 and 82 hours after pitch, showing a slight change in slope in the gravity graph, and a 'bump' in the pH graph (the other 'bump' in the pH graph at ~44hrs seems to correlate to aeration).
It is clear that the yeast are active well before a drop in gravity, this is shown by the drop in pH before ~24hrs (when a drop in gravity was first detected). This corresponds to the acclimation period which yeast go through commonly called the 'lag phase'; it would seem that instead of active sugar metabolism, they are more concerned with making an adequate environment for themselves at this point.
As to the differences, it would seem that the boiled must had a higher pH throughout the process until the end of fermentation. This is contrary to common belief that boiling (and skimming) reduces the buffering capacity of mead musts, however, this may be an outlier as the honeys chosen for the must composition do naturally have higher mineral and ash contents than other honeys (avocado and lychee are particularly rich in both, the brazilian pepper had a very high pollen content, and the beach plants have a higher mineral concentration than average (White Jr)).
Also the boiled mead fermented a little faster (about 2 days, though the data is not accurate to the hour, hence it's non-inclusion in the graphs).
Both have been cold crashed for 2 weeks at 5C, and have been treated with sulfites (an addition of 1 campden (Kmeta) was added to each gallon container, this method was chosen for its prevalence throughout the mead and winemaking community). They will age for another 9mos before being racked and bottled. Bottle aging will be in 12oz beer bottles with O2 absorbing caps, and evaluation will be held at several points in their lifetimes (hopefully ~1yr, 2yr, and 3yr, but we'll see).