Changes

[https://www.biorxiv.org/content/10.1101/2021.07.26.453768v1 Foster et al. (2021)] found similar findings in 5 out of 6 strains of kveik (two Hornindal strains, one Laerdal strain, one Ebbegarden strain, one Granvin strain, and one Sigmund Voss strain). Using HS-SPME-GC-MS and PCA biplot analyses to measure and plot fatty acids, ethyl esters, alcohols, and acetate esters, the researchers found that, with the exception of the Ebbegarden strain, the kveik strains grouped together while the control strains (Cal ale, Vermont, and Kolsch) grouped together (the Belgian strain "St. Lucifer" from Escarpment Labs was another control strain and formed its own flavor profile grouping). For example, octanoic acid, ethyl hexanoate (pineapple, tropical), ethyl octanoate (tropical, apple, cognac), and ethyl decanoate (apple) were all produced above threshold for all (except Ebbegarden) of the kveik strains and one control strain, the Belgian strain "St. Lucifer" from Escarpment Labs, but not the Cal ale, Vermont, and Kolsch control strains. This demonstrates that the flavor profile of many but not all kveik strains is unique from at least some typical brewing strains. The flavor profile plotting also determined that temperature played a roll in flavor with all but the Ebbegarden kveik strains clustering together at 5-42°C versus 15-22°C. For example, ethyl octanoate and ethyl decanoate were produced at the higher temperature range in the kveik strains (except Ebbegarden). The higher alcohol 1-octanol, which has a pleasant citrus character, was only produced above threshold by Cal ale and Kolsch at 15°C and Vermont at 22°C, it was produced above threshold by the kveiks and St. Lucifer strains at a much wider temperature range. Similar results were found for isoamyl acetate. Phenethyl acetate, on the other hand, was only produced above threshold by Hornindal1, Hornindal2, Laerdal and St. Lucifer regardless of temperature <ref name="Foster_2021" />. For more details on the Foster et al. (2021) study, see also [https://www.garshol.priv.no/blog/423.html Lars Garshol's blog post] and , study co-author [https://www.facebook.com/groups/MilkTheFunk/posts/4824280584266784 Richard Preiss's summary on MTF], and [https://brulosophy.com/podcasts/the-bru-lab/ Bru Lab Podcast Episode 031 - Kveik Fermentation Temperatures w/ Richard Preiss].