Northern_Brewer
British - apparently some US company stole my name
See eg https://www.escarpmentlabs.com/single-post/2019/11/01/The-impact-of-pitch-rate-on-kveik-ferments
it looks like there is a trend for increased aroma intensity for some of the kveiks (Voss and Hornindal) as the pitch rate decreases. However, this is not true for Arset and Ebbegarden, where the trends are less clear. So this tells us that there is not a one-size-fits-all rule for kveik pitch rate and aroma production.
Factoring in fermentation rate, fermentation specs and aroma production, we think that 7 million cells / mL strikes a good balance between the low and high pitch rate, but that the sweet spot could be somewhere between the two. We have done collaboration brews with partner breweries at around the 3 million cell / mL rate with good results and minimal impact on fermentation kinetics.
A caveat for this study is that the yeasts were produced under ideal conditions and never left the lab. The results may be different for slurry that is shipped and stored for several weeks. But if brewers want to attempt this kind of study themselves, we're all ears!
We hope this was helpful. The coles notes? Pitch rate matters less than you might think. There are clear trends for some strains (Voss and Hornindal) but not others (Arset and Ebbegarden).