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Kveik

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Kveik has adapted to being fermented at relatively warm temperatures without producing off-flavors (fusel alcohols, diacetyl, or acetaldehyde), usually in the range of 30-40°C (86-104°F), but also as high as 43°C (109°F). The beer is finished fermenting within a day or two at these warmer temperatures. Årset kveik has been fermented as low as 4°C (39°F), which produced a clean and drinkable beer with a fruity aroma. They have a high alcohol tolerance of around 13-16% ABV <ref name="garshol_preiss_mbaa">[https://www.mbaa.com/publications/tq/tqPastIssues/2018/Pages/TQ-55-4-1211-01.aspx How to Brew with Kveik. Lars Marius Garshol and Richard Preiss. MBAA Technical Quarterly, 2018 Q4.]</ref>. [http://www.omegayeast.com/ Omega Yeast Labs] describes their two isolates (Voss and HotHead) as being non-phenolic, fruity, and complimenting American citrus hops. They also note that the yeast has a very high temperature range (~68-98°F or ~20-37°C), attenuates high, tends to flocculate well, and also tends to ferment faster at the mid to high temperature ranges, while producing similar ester profiles throughout the entire temperature range. Other kveik cultures generally produce subdued aromas below 20°C (68°F); different kveik cultures react differently at different fermentation temperatures <ref name="garshol_preiss_mbaa" />.
Pitching rates for kveik are also one of the unique things about these cultures. In general, pitching at typical ale pitching rates produce subdued esters. In order to express the yeast fermentation profile more, kveik cultures are traditionally pitched at a very low rate, perhaps somewhere around the 1-2 million cells/mL for 15-20°P wort. Brewers should experiment with the pitching rates for a given kveik strain of mixed culture, and determine which pitching rates produce desirable results. Oxygen should be at least in the 5-8 ppm range, although 10-12 ppm might be beneficial. [[Kveik#Kveik_Ring.2FKveikstokk_and_Drying|Dried kveik cultures]] have a cell density of around 9-18 billion cells per gram of dried yeast (Fermentis has around 31 billion cells per gram by comparison), and so pitching as little as 10 grams of dried kveik into 100L of wort could be fine. Dried kveik is generally rehydrated in first runnings for about 2-4 hours before pitching into the main batch(lautering in traditional farmhouse brewing can take a long time), with a [http://www.garshol.priv.no/blog/367.html yeast scream] being traditional to ward off evil spirits. Kveik cultures are heavily dependent on nutrients, and wort that is lower than 1.050 can benefit from doubling nutrient additions <ref name="garshol_preiss_mbaa" />.
Kveik mixed cultures tend to be very flocculant, even though only about 48% of the individual strains are highly flocculant (it is thought that high flocculating strains help the lower flocculating strains to flocculate). Top-harvested kveik form a thick krausen and tends to float on top of liquid even when stored in the fridge, while bottom-harvested kveik tends to form a thin layer of krausen (see the [http://www.garshol.priv.no/download/farmhouse/kveik.html Farmhouse yeast registry] to see which kveik cultures are top vs bottom harvested; the listed harvesting method should be continued so as to continue to select for the correct strains). Harvested kveik can be stored in the refrigerator as a slurry, and survive 1-2 years (a starter should be made after about 6 months of cold storage). Attenuation ranges from 60-90% for single strains, but for mixed cultures, the attenuation is usually on the higher side <ref name="garshol_preiss_mbaa" />.

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