Changes

Kveik was passed down from generation to generation within the family, and also shared among fellow brewers in the region. In this way, kveik evolved differently than the two major beer yeast groups that are used in industrialized brewing. While mostly POF-, a trait that is selected for in many beer yeast strains that prevents the yeast from producing 4-vinylguaiacol phenol, other traits are reflective of how this yeast was used by traditional farmhouse brewers of the region. For example, as far back as 1621 (and probably prior), kveik was often stored dry on wooden logs called "kveikstokker" for up to a year or longer. Kveik was typically inoculated directly into the wort by submerging the kveikstokker into the wort at 30-40°C. The wort was often high gravity of around 1.080 SG, and the beer was served just after 1-2 days of fermentation beginning at this hot inoculation temperature. The kveik was then taken from the fermenter and dried until its next use. It has been proposed by Tyrawa et al. (2017) that this treatment has produced yeast strains that are genetically distinct phenotypically from other domesticated yeast strains used in industrial brewing in Europe <ref name="Tyrawa_2017">[https://www.biorxiv.org/content/early/2017/09/27/194969 Traditional Norwegian Kveik Yeasts: Underexplored Domesticated Saccharomyces cerevisiae Yeasts. Richard Preiss, Caroline Tyrawa, George van der Merwe. 2017.]</ref>.  At one time kveik was the only available form of yeast in Norway (and, of course, similar methods for reusing yeast were used all over the world prior to Emil Chr. Hansen's introduction of the pure-yeast system in 1883). However, the existence kveik has mostly disappeared in recent times. Today kveik remains in the districts of Hardanger, Voss, Sogn, Nordfjord, and Sunnmøre, at least. Today, kveik is only used by homebrewers who still brew in the traditional methods of Norwegian farmhouse brewing <ref name="larsblog_norwegian_farmhouse">[http://www.garshol.priv.no/blog/259.html Norwegian farmhouse ale. Larsblog. 10/27/2013. Retrieved 01/14/2016.]</ref>. Kveik was sometimes also used to ferment bread. Farmers seemed to have different preferences for top or bottom collecting their kveik <ref name="larsblog_kveik"></ref>.