Changes

* [https://homebrewingcondor.blogspot.com/2018/08/conservare-il-kveik-su-legno-kveikstokk.html Antonio Golia's write up on making and using a kveikstokk (in Italian; use an online translator).]

Dried kveik should be stored in the freezer, and has been known to be recoverable after 20 years when stored in this way. While recovery of very old dried kveik may be possible using microbiological techniques, very old dried kveik might not be viable enough for brewers to revive using simple starter techniques. [http://suigenerisbrewing.com/index.php/2019/08/28/drying-kveik-the-grand-finale Microbiologist Dr. Bryan Heit measured the viability of kveik] that was dried using a dehydrator and stored in a home freezer and found that viability decreased by about 6-8% per month. Dr. Heit estimated (and then later confirmed via cell counts) that at 6 months, the kveik would be at about 50% viability, which is good enough to pitch directly into wort without a starter. Therefore, if the kveik has been frozen for 6 months or less, dried kveik can be thawed and simply added to a liter or so of ~30°C (86°F) wort for 2-4 hours before adding that to the main batch of wort. If the dried kveik is older than 6 months, a starter is recommended. Dr. Heit used Voss kveik for his experiment, and included some limitations such as sample size, using kveik from a yeast cake instead of using fresher yeast from top cropping or a starter, using a yeast cake with a high hop content (while hops are not toxic to yeast, a high content of hops could further stress the yeast), using a dehydrator that had high and fluctuating temperatures instead of a better quality dehydrator (Dr. Heit recommends drying at 35-40°C), and probable under-estimates of viability due to using trypan blue dye, which is known to stain both dead cells and cells that are alive but are undergoing cell division <ref name="garshol_preiss_mbaa" /><ref>[http://suigenerisbrewing.com/index.php/2019/08/28/drying-kveik-the-grand-finale Dr. Bryan Heit. Sui Generis Blog post about dried kveik viability over time. 08/28/2019.]</ref>.