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added White Labs data on pitch rate
They monitored specific gravity, FAN consumption, pH change, alcohol/glycerol production, and aroma compound production (using GC-MS). All ferments were performed in triplicate. Their major findings are listed as follows:
* A low pitching rate of 1 million cells/mL attenuated the sample slightly slower than the higher pitching rates, but all pitching rates resulted in a similar finishing gravity, including the Vermon Vermont Ale yeast. The kveik fermented faster than other brewer's yeast even at the lower fermentation temperature.
* There were no clear trends as far as how much FAN was consumed by the kveik based on pitching rate, although Årset and Vermont Ale yeast consumed less FAN for the lowest pitching rate. They concluded that high FAN levels are recommended, especially for lower gravity wort.
* Terminal pH was lower for Årset and Ebbegarden, and a little higher for the other strains (~4.15 versus ~4.4); however, pitching rate did not correlate to any patterns.
For the full details of this study, including the full data results, see the [https://www.escarpmentlabs.com/single-post/2019/11/01/The-impact-of-pitch-rate-on-kveik-ferments Escarpment Labs blog page] and the associated [https://www.facebook.com/groups/MilkTheFunk/permalink/3020798864614974/ MTF post].
White Labs also published data on their website regarding pitch rate and temperature differences for four of their kveik isolates: WLP518, WLP519, WLP520, and WLP521. Four trials were conducted total, with two trials at 0.25 mil cells/mL/°P (low pitch rate) at 20°C and 32°C, and two trials at 0.75 mil cells/mL/°P (high pitch rate) at 20°C and 32°C (see pitch rate/temperature and attenuation differences below). They measured diacetyl and acetaldehyde differences between the four fermentations. Of the significant results, they found the following: <ref name="white_labs_experiment">[https://www.whitelabs.com/news-update-detail?id=69&type=NEWS White Labs website. "The Kveik Experiment". 05/02/2022. Retrieved 06/11/2022.]</ref>
* WLP518 produced higher acetaldehyde at a high pitch rate at 32°C, but not at 20°C.
* WLP519 produced higher acetaldehyde at a high pitch rate at 20°C, but the opposite was true at 32°C.
* WLP520 produced slightly more diacetyl and acetaldehyde at a high pitch rate at 20°C and 32°C.
* WLP521 produced more diacetyl at a low pitch rate at 20°C, and sightly higher at 32°C. It also produced significantly more acetaldehyde at a high pitch rate, especially at 32°C (less so at 20°C).
* White Labs reported that their sensory panel preferred the beers fermented at the warmer temperature of 32°C vs 20°C (data not published).
See also: