Kveik

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The book "Historical Brewing Techniques" by Lars Marius Garshol.
Sigmund Gjernes holding a Kveik Ring (gjærkrans). Photo by Lars Marius Garshol.

Kveik is a dialect word for "yeast" in Norwegian ("gjær" is the common word for "yeast" in Norwegian [1]), and today specifically refers to non-purified yeast that contains multiple domesticated (not wild) strains of S. cerevisiae and has been reused for generations in traditional Norwegian farmhouse brewing. Originally the word was used as a verb to mean "to start" or to "begin life" [2][3] (~1 hour in).

The words "kveiken", "kveika", and "kveikja" are the dialectic definite articles for the word "kveik", which all translate to English as "the kveik" [5]. The term "kveik" does not refer to a style of beer, but only the yeast used in traditional Norwegian farmhouse brewing (Garshol has encouraged brewers brewing non-farmhouse styles with kveik to call them "X Style Beer Brewed with Kveik" or something similar; see Terminology for more information on suggested approaches to naming classic styles fermented with kveik [6]). The word "kveik" is specifically used in the western part of Norway for family-owned, non-purified yeast, while other words such as "gjester" are used by central Norwegians, "gong" is used by locals in eastern Norway, "family yeast" is used by some Lithuanian brewers, and "hemjäst" is used by locals in Gotland. The term "landrace yeast" has been proposed to refer to kveik as well as other non-kveik farmhouse yeast cultures (for example, Simonaitis) [7][8][6].

Kveik yeast are extremely diverse genetically, presenting characteristics that are not typical in other brewing yeasts [9]. Most farmhouse brewers have started buying their yeast, but some kveik cultures have been passed down from generations and inherited by modern farmhouse brewers in Norway who still use this yeast today and brew with traditional farmhouse methods. Much of the knowledge about kveik and historical farmhouse brewing in Norway has been researched and publicized by Lars Marius Garshol on his blog, Larsblog, and in the book Beer and Brewing Traditions in Norway by Odd Nordland (1969). In recent years kveik cultures have been sent to yeast labs for propagation and distribution to brewers around the world [10]. The use of kveik is one of the many traditional methods still used by a few farmhouse brewers and homebrewers in Norway, along with other historical methods such as infusing the mash or boil with juniper (Juniperus communis [11]), not filtering, using short fermentations to achieve low carbonation, the use of wood-fired copper or iron kettles, and sometimes not boiling the wort (Raw Ale) [12]. Kveik can also be used effectively to ferment a wide range of non-farmhouse styles, such as New England IPA and English beer styles, as well as cider, mead, and mash/wash for distillation.

Farmhouse yeasts from other countries such as Lithuania and Russia have been found to be both genetically different and express different fermentation profiles than the kveik yeasts of Norway, and are therefore not referred to as "kveik". See the Farmhouse Yeasts in Other Countries page.

For a comprehensive list of kveik and other landrace farmhouse yeasts, see the Farmhouse Yeast Registry maintained by Lars Garshol.

"I see this is about to become a myth, so just to clear things up: kveik is not a style of beer. It's farmhouse yeast." ~ Lars Marius Garshol, December 29, 2016 [6]

Brief History and Description of Kveik

Brief History

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 genetic 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 before being re-used in a new batch of beer (the process of re-using yeast from batch to batch is known as "backslopping" in brewing[13]). 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. If the kveik went sour or died, brewers would borrow kveik from their neighbors, which was another way of preserving kveik through the centuries. Kveik was sometimes also used to ferment bread. It has been proposed by Preiss et al. (2018) that this treatment has produced yeast strains that are genetically distinct phenotypically from other domesticated yeast strains used in industrial brewing in Europe [14].

Farmers seemed to have different preferences for top or bottom collecting their kveik for storage [10]. Kveik was stored in many ways. It was often stored in bottles with water or in a well. It was also dried on straw rings, on linen, or pieces of wood with holes drilled through them called "yeast logs". Often ashes were used to help dry the kveik quickly, or in the case of yeast logs, were lowered into the fermentation vessel to collect the yeast and then rolled in flour and allowed to dry for a few minutes, then dipped again to repeat the process. The log was then hung to dry. Although dried kveik was said to last for months or maybe longer, fresh kveik was always preferred and often given away to those who needed new kveik (moldy kveik was thrown away) [10].

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 of kveik has mostly disappeared in recent times. Today kveik remains in the districts of Hardanger, Voss, Sogn, Nordfjord, and Sunnmøre, at least. Kveik is only used by homebrewers who still brew in the traditional methods of Norwegian farmhouse brewing, although the recent spreading of kveik throughout the world has led to a resurgence in its usage to make various types of beer, including non-farmhouse style beers [15].

Thanks to efforts by Lars Marius Garshol and Håken Hveem, and Norwegian farmhouse brewers Svein Rivenes, Sigmund Gjernes, Bjarne Muri, Terje Raftevold, and others, kveik has been made commercially available to brewers around the world. Much of the analysis has been performed by the National Collection of Yeast Cultures (NCYC) and Escarpment Laboratories. See also the Farmhouse Yeast Registry being maintained by Lars Marius Garshol.

See also:

Terminology

Yeast Lab Analysis

 
Diagram of types of yeast versus traditional farmhouse styles by Richard Preiss [8].
 
The dried kveik samples (Stordal) showed much better viability/cell health (less granulated/wrinkly appearance) than the liquid samples (eg Hornidal). However, some of the liquid samples were pretty healthy too (Voss). Source Richard Preiss of Escarpment Labs.

Species and Phylogeny

Analysis has also been performed at the Norwegian University of Science and Technology (NTNU) by Truls C Rasmussen, as well as Escarpment Laboratories.

In general, most of the cultures of kveik that have been analyzed contain more than one strain of S. cerevisiae. The exact number of strains that is present in a given kveik culture is difficult to analyze; generally labs with better equipment and more time can identify more strains than others. Some kveik cultures contain multiple strains of closely related strains of S. cerevisiae, while others contain a more diverse group of strains [16]. The kveik cultures with closely related strains defy what a "strain" isolate is; Richard Preiss describes these kveik cultures as being "heterogenous but related communities", meaning that there can be a lot of genetic overlap between subpopulations in a kveik culture and where one strain begins and another ends is not possible to define [19]. S. cerevisiae was the only species in all of the kveik cultures analyzed by Preiss et al. (2018). Of the 9 kveik cultures analyzed by Preiss et al. (2018), only Muri (which has since been found to be commercially available Bavarian Weizen yeast and not a landrace farmhouse yeast at all; see Landrace Yeast), Simonaitis, and Stranda contained only one strain of S. cerevisiae, while all of the others contained more than one strain of S. cerevisiae up to 9 strains in the case of Granvin (see this table from the paper). A Master's Thesis by Nadia Marlen Aasen from Norwegian University of Life Sciences isolated 4-10 strains from 4 different kveik cultures: Ørjasæter, Otterdal, Gausemel and Gamlegrua. As with Preiss (2018), the only species of yeast found was S. cerevisiae. While only yeast was found in Otterdal and Ørjasæter, the Gausemel also had two bacteria species, Acetobacter malorum and Lactobacillus plantarum, and the Gamlegrua also had L. plantarum [20].

Genetically, kveik yeast strains form their own group of closely related domesticated ale strains that are a subgroup of the "Beer 1" yeasts (Belgian/Germany/UK/US yeast strains) from the Gillons/White Labs (2016) study that sequenced previously known ale strains and found them to make up two genetically related groups called "Beer 1" and "Beer 2" (see Saccharomyces History of Domestication and "A family tree for brewer's yeast" by Lars Marius Garshol). The closest related domesticated strains were 3 German hefeweizen strains; however, this relation is likely just due to both groups being hybrids rather than having any historic relation [14]. None of the kveik strains sequenced by Preiss et al. (2018) contained the STA1 gene for diastatic activity, which is expected since all of the diastatic yeasts belong to the "Beer 2" group [21].

Although whole genome sequencing of more kveik strains is needed in order to fully flesh out a family tree of kveik [22], based on the 6 strains that were analyzed, kveik strains seem to be divided into two related genetic groups, with the Simonatis Lithuanian strain and a Norwegian bread yeast falling outside of these two groups completely, which arguably categorizes them to not actually be considered "kveik". The two groups of kveik probably originated from two ancestors that were hybrids between a "Beer 1" yeast and wild yeast. Interestingly, the kveik cultures that have multiple strains have strains from both genetic groups of kveik. For example, Hornindal, Granvin, Laerdal, and Stordal Ebbergarden all contained strains from both genetic groups of kveik. Overall, their genetic diversity is wider than the genetic diversity of other "Beer 1" subgroups [14]. See this updated family diagram of yeast.

Preiss et al. (2018) also measured the fermentation characteristics of individual kveik strains in their study, the first published data in this regard for kveik. At 86°F (30°C) they found that 11 of the 24 pure strains of kveik outperformed the best control strain (WLP002) in fermentation rate. There was still a very wide range of attenuation rates between the kveik strains (60-90%). Of the 6 strains that had their DNA sequenced, all but one of the Granvin strains fermented maltotriose. All of the strains tested were POF- (meaning they did not produce significant 4-vinylguaiacol phenol). One of these Stordal Ebbegarden strains also contained a unique mutation on the FDC1 gene that results in the inability to produce phenols and has not been reported before in science. They also found that kveik strains tend to produce fatty acid esters at levels that are typical for other domesticated yeast strains, such as ethyl caproate (pineapple, tropical; threshold 0.21 ppm), ethyl caprylate (tropical, apple, cognac; threshold 0.9 ppm), and ethyl decanoate (apple; threshold 0.2 ppm). The kveik strains studied did not produce high levels of the isoamyl acetate ester (banana) and generally lower levels of the fusel alcohol isobutanol compared WLP001 and WLP002. Strangely, 5 of the 6 strains that were analyzed could form spores, which is not typical for brewers yeast [14].

The kveik strains studied by Preiss et al. (2018) displayed unique abilities as far as withstanding stress in their environment. Most of the strains at least doubled their growth at 43°C and grew to their maximum potential at 40°C, while the control strains WLP001, WLP002, and WLP029 showed limited growth at those temperatures. This demonstrates kveik's ability to withstand high-temperature fermentations. All strains tested died at 45°C [14].

Kveik strains were also demonstrated by Preiss et al. (2018) to have a higher tolerance to alcohol than some of the domesticated strains tested (WLP001, WLP002, and WLP029), as well as unique flocculation characteristics. Most of the kveik strains doubled in growth in media with 14% ABV ethanol, and about half of them doubled in growth in 16% ABV ethanol media. Half of the strains of kveik were highly flocculant, but some other strains were very poor flocculators. It is possible that since kveik is a mixed culture of several strains of yeast that the highly flocculant strains assist the others in flocculation thus diminishing for the other strains to evolve flocculation properties [14].

See also:

Sensory and Fermentation Profile

The general flavor profile of kveik yeast is ester-driven and non-phenolic, although a wide range of subtle differences can exist between strains. Kveik in its traditional form is usually a blend of closely related strains. The "Stranda" kveik was described as "lemon, nuts, grain, and straw" by Lars Marius Garshol. The "Hornindal kveik" with bacteria was described as "fruity, milky caramel, honey, and mushroom with a very unique aroma" [14].

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 [16]. 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 [16]. Despite the fast fermentation timeframe that traditional farmhouse brewers employ and the high flocculation that some kveik have, some kveik and some beer styles/brewing conditions may still require or benefit from a more traditional brewing schedule. For example, some kveik may need more time to clean up diacetyl or hydrogen sulfide, to flocculate or settle out completely, or to completely finish attenuation. Keep mind that the farmhouse beers, brewing techniques, and drinking culture differ quite a bit from modern beers, modern brewing techniques, and modern beer packaging/consumption. For example, shelf stability is generally not a concern for farmhouse brewers. Fermenting beer with kveik on the same fast time schedule and in the same ways as the traditional farmhouse beers and without making adjustments such as increased nutrients or increased conditioning time might result in less than stellar beer for modern styles [23].

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 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 [16].

Kveik cultures make identifying individual strains within them difficult because the strains are closely related and there is often not a clear distinction between "strains", nor is there a clear definition of what makes a strain truly unique within the total population of strains that are found in a single kveik culture. Richard Preiss describes kveik cultures as being "heterogenous but related communities", meaning that there can be a lot of genetic overlap between subpopulations in a kveik culture. What exactly is meant by "strain" within the context of kveik cultures has not been defined, and so discussing individual strains of kveik is an inadequate way of discussing kveik [19].

Kveik cultures have a wide range of fruity aromas, which is a result of above-threshold production of fatty acid esters, such as ethyl decanoate and ethyl caprylate [16]. Richard Preiss from Escarpment Laboratories shared his sensory notes after doing trial fermentations with various kveik strains/cultures. Fermentations were at 30°C in standard wort (1.050, 20IBU) with single strains, not the mixed cultures. 2/3 tasters were blind to the beers and order prior to tasting. This is a single data point on sensory information [24]:

  • Sykkylven 1 - clean, fruity, malty, rum-like. big, round, malty, slightly hot
  • Sykkylven 2 - subtle fruit, malt accented, slightly lagery-sulfury, lightly floral. medium body
  • Laerdal 2 (Laerdal 1 - data not available) - Lightly fruity, slight rubber, floral, sweet taste
  • Stranda 1 - citrus, red apple, very clean and dry, balanced
  • Stordal (framgarden) 1 - big citrus ester, slightly hot, red apple, floral, malty
  • Stordal (framgarden) 2 - red apple, slight crisp/sulfury (pleasant) lagery character, floral, slight tropical fruit, slight tartness
  • Stordal (ebbegarden) 1 - rum-like, slightly hot, medium mixed esters, round and malty
  • Stordal (ebbegarden) 2 - Christmasy, citrus, red apple, floral, clean and balanced flavour
  • Muri 1 (not related to kveik genetically; later found to be Bavarian Weizen yeast) - Earthy, herbal, sulfury, apple, pear, very slight clove, not super dry despite ridiculous attenuation (~95%)
  • Voss (Gjernes) 1 - Orange, floral, balanced flavour, good body
  • Voss (Gjernes) 2 - Cidery, floral, slight earthiness, slight orange, clean, dry
  • Hornidal 1 - Tropical, pineapple, rum-like, caramel, citrus, balanced malt/hop
  • Hornidal 2 - Floral, rose-like, sulfury, orange, rum-like, very malt accented
  • Hornidal 3 - Orange, red apple, rum-like, caramel, balanced
  • Granvin 1 - Lower intensity orange, red apple, slight pineapple, textbook “Kveiky”, balanced
  • Granvin 2 - Balanced esters, not as intense - citrus, slight (pleasant) sulfur, dry and thin
  • Granvin 3 - very muted aroma, clean flavour
  • Granvin 4 - floral (rose), honey, slight diacetyl, medium-low esters, complex but not necessarily good
  • Granvin 5 - light fruit, light floral, rubber, sweet taste.
  • Granvin 6 - fruity, floral, rum-like, citrus, slight diacetyl, balanced flavour
  • Granvin 7 - Slight fruity, very thin and astringent
  • WLP001 (control) - very fusely/hot, subtle floral note.

Note regarding Granvin strains: Preiss is still trying to sort out which Granvin yeasts are duplicates and which are unique.

Final Beer pH

Kveik also tend to finish beers at a slightly low pH than conventional ale yeast and lager yeast. In a survey of data from around 60 strains of yeast total, Escarpment Labs showed that kveik strains on average finished around 4.25 final beer pH while conventional ale/lager yeast strains finished on average around 4.50 final beer pH for the same wort. This can have an impact on the overall sensory nature of kveik. For example, a lower pH is sometimes associated with the perception of a thinner body as well as a harsher and more astringent hop character. The use of buffering minerals in the mash such as baking soda, lime, or chalk, can help adjust the pH back up if desired [25][26].

This tendency to producer slightly lower pH beers than normal brewing yeast is not universal, however. Fermentation conducted with unpurified original kveik cultures may have different results than single isolate strains. For example, Nadia Marlen Aasen's Master's thesis from Norwegian University of Life Sciences found that the same wort (Weyermann Pilsner malt, 60 minute Magnum hops at 18 IBU, and the wort soaked in 1 kg of juniper twigs per 10 liters of wort) fermented with US-05 finished between 3.8-4.0 pH, Ørjasæter kveik finished at 4.1-4.2 pH, Gamlegrua kveik finished at 4.1-4.3, and Gausemel kveik finished at 3.8-4.0 pH [20].

See also:

Pitching Rate

Pitching rates for kveik are also one of the unique things about these cultures. Kveik cultures are traditionally pitched at a very low rate, perhaps somewhere around the 1-2 million cells/mL for 15-20°P wort. However, pitching at normal ale pitching rates should not produce negative results, and brewers should experiment with the pitching rates for a given kveik strain of mixed culture and determine which pitching rates produce the most desirable results. Escarpment Labs recommends pitching 70% of normal pitching rates, but Richard Preiss reported no issues so far pitching at 25% of normal pitching rates [27]. Omega Yeast Labs recommends normal pitching rates for kveik, but reported no significant difference between under-pitching and normal pitching rates; however, reports of off-flavors might be related to extreme under-pitching and/or lack of nutrients [28][29] (~1:03:20 mins in). Oxygen should be at least in the 5-8 ppm range, although 10-12 ppm might be beneficial. 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 is 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 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 [16]. Richard Preiss recommends 180+ ppm of free amino nitrogen (FAN), along with vitamins (yeast nutrient blends offered by many yeast labs should be able to satisfy these requirements; contact the vendor to find out the specified FAN dosage and vitamin content) [30][31].

Escarpment Laboratories presented the first controlled experiment and data set for how pitching rates might affect kveik. The lab fermented their Årset blend (a selection of several strains from Årset; see this explanation from Richard Preiss), Ebbegarden (contains two strains from the original Ebbegarden), the Escarpment Labs Voss single isolate, the Escarpment Labs Raftevold's Hornindal (contains two strains from the original Raftevold Hornindal), and the Vermont ale strain which was used as the control. The strains were fermented at 20ºC (the lab would have preferred to ferment at a warmer temperature, but this was a part of a much larger fermentation experiment with many other brewing strains and they were limited due to limited temperature control equipment). The pitch tested rates were:

  1. 1 M/mL (1 million cells per mL, 10% of a typical pitch rate)
  2. 7 M/mL (7 million cells per mL, 70% of a typical pitch rate)
  3. 10 M/mL (10 million cells per mL, a typical pitch rate)

They monitored specific gravity, FAN consumption, pH change, alcohol/glycerol production, and aroma compound production (using GC-MS). All ferments were performed in triplicate. Their major findings are listed as follows:

  • A low pitching rate of 1 million cells/mL attenuated the sample slightly slower than the higher pitching rates, but all pitching rates resulted in a similar finishing gravity, including the Vermon Ale yeast. The kveik fermented faster than other brewer's yeast even at the lower fermentation temperature.
  • There were no clear trends as far as how much FAN was consumed by the kveik based on pitching rate, although Årset and Vermont Ale yeast consumed less FAN for the lowest pitching rate. They concluded that high FAN levels are recommended, especially for lower gravity wort.
  • Terminal pH was lower for Årset and Ebbegarden, and a little higher for the other strains (~4.15 versus ~4.4); however, pitching rate did not correlate to any patterns.
  • No discernible trend in over all ester production depending on pitch rate, although there were some differences depending on ester type and kveik.
  • Kveik produce more organic acids than Vermont Ale yeast, duplicating results from the previous Escarpment Labs study on kveik.
  • Årset and Ebbegarden produced citronellol at levels similar to Vermont Ale yeast, which indicates that these cultures might be capable of biotransformation similar to the Vermont Ale strain.
  • There was 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 Årset and Ebbegarden, where the trends were less clear.

For the full details of this study, including the full data results, see the Escarpment Labs blog page and the associated MTF post.

See also:

Temperature and Growth Rate

While very warm fermentation temperatures have an impact on the speed of potentially attenuation of kveik, temperatures on the higher end of the scale can have a slightly negative impact on the growth rate of some kveik cultures. Aasen's Master's thesis reported that for all three kveik cultures tested (Ørjasæter, Gamlegrua, and Gausemel) the growth rate was slightly higher when incubated at 22°C and/or 30°C compared to being incubated at 37°C. The cultures tended to reach peak cell growth at around day 2 or 3, and then experienced a slight decline until day 7, with this decline after day 2 or 3 being slightly steeper at the hotter incubation temperature of 37°C. The warmer incubation temperature of 37°C did not result in faster growth than the cooler temperatures of 22°C and/or 30°C. Therefore, for optimal growth of kveik for starters or yeast labs, a temperature of 22°C or 30°C might be optimal for some kveik cultures [20].

Temperature and Attenuation

Higher fermentation temperature seems to not have a large impact on final gravity and attenuation. Aasen's Master's thesis reported statistically insignificant or minimal differences in finishing gravities at different fermentation temperatures for the three kveik cultures tested (Ørjasæter, Gamlegrua, and Gausemel):

Yeast/Kveik [20] Temp (°C) Original Gravity Final Gravity
Gamlegrua 30 1.076 1.017
37 1.076 1.018
Gausemel 30 1.076 1.015
37 1.076 1.017
Ørjasæter 30 1.076 1.015
37 1.076 1.019

Temperature and Aromatic and Sensory Compounds

Just as with other strains of Saccharomyces cerevisiae used in fermentation, the fermentation temperature can have a significant effect on the different aromatic and flavor compounds produced by kveik Aasen's Master's thesis looked at fermenting three different full culture kveiks, Gamlegrua, Gausemel and Ørjasæter, and US-05 as a control. She tested three different fermentation temperatures, 22°C, 30°C, and 37°C. In general, after 7 days of incubation time, all of the yeasts had higher levels of the esters ethyl acetate, isoamyl acetate,and ethyl hexanoate at the 22°C or 30°C, and nearly half the amounts of esters at 37°C. These were esters were also measured at day 2, and at that time they were much higher in the 37°C fermentation, suggesting that prolonged exposure to the warmer temperature may have dissipated these esters. Ethyl octanoate tended to have slightly higher amounts at 22°C or 30°C, but the differences between the different fermentation temperatures were smaller, and in the case of the Gausemel kveik there was no significant different at all for this ester [20].

Other Sensory Data

Various Interesting MTF Threads

Lactic Acid Bacteria and Wild Yeast Contaminations

Some of the kveik cultures that are not isolated cultures have reportedly been contaminated with lactic acid bacteria. These contaminations probably occurred during handling of the yeast at some point. See Justin Amaral's statements regarding this issue. The lactic acid bacteria found in contaminated kveik cultures can be inhibited by ~10 IBU [32]. Traditionally, if contaminating microorganisms start having an impact on the flavor of the beer, the brewer would throw away their kveik and borrow a fresh culture from a neighbor [16].

See also:

Juniper Antimicrobial Effect

Juniper twigs partially inhibit Lactobacillus growth. Juniper needles, ripe berries, and unripe berries have little to no significant impact [20]. See Lactobacillus "Other Plant Type Tolerance" for more information.

Kveik Ring/Kveikstokk and Drying

 
Kveikstokk with yeast slurry on it. Images provided by Antonio Golia ("Homebrew Condor").

As Norwegian farmhouse brewers only brew 2-3 times per year, kveik has adapted to being dried and stored for long periods of time in-between usage, which is unique among most domesticated yeast [16]. Storing the kveik in a dried form allows the yeast to survive longer than if it is kept as a wet slurry, and might help prevent contaminants from surviving. Kveik was often dried on parchment paper and kept in bags in the freezer. Wooden carvings known as a "kveik ring" or a "kveikstokk" were also sometimes used to store dried kveik, although this might be an older practice compared to drying kveik on parchment paper. Using a kveik ring or kveikstokk is simple: drag the kveik ring (more broadly known as a "twisted torus" [33], or more specifically called a "gjærkrans" or "yeast wreath" in Norwegian when used for yeast [34]) or kveikstokk through the krausen of a fermenting beer, and then hang the ring/kveikstokk to dry. On the next batch, the ring/kveikstokk is dunked into wort to reactivate the yeast [35]. Note that not all yeast reacts well to drying. Kveik has this exceptional ability. For example, Brettanomyces is known to not be tolerant of drying/desiccation [36].

Drying Instructions

Using Dried Kveik and Viability Over Time

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. 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 [16][37].

See also:

History and Crafting How To's

Kveik Rings for Sale

Commercial Availability

This is a summary of commercially available kveik cultures. See the above descriptions, the Farmhouse Yeast Registry, and the vendor's website for more information about the cultures. Most are single strain isolates, while some contain multiple strains or the native "unpurified" mixed cultures (this is of interest to some brewers, especially Norwegian brewers, because single isolates potentially perform differently than original cultures with multiple strains and as such will be denoted in the Notes column). Note that strain information can be misleading because the nature of kveik cultures make talking about individual strains difficult due to the strains being closely related yet diverse. Richard Preiss describes kveik cultures as being "heterogenous but related communities", meaning that there can be a lot of genetic overlap between subpopulations in a kveik culture and where one strain begins and another ends has yet to be defined (see Recent Lab Analysis above) [19]. Additionally, it is legal and quite common for yeast labs to culture strains from another yeast lab and brand them as their own, thus many single isolates are likely to be duplicates of whichever lab initially isolated them (this is unverifiable unless the yeast lab in question shares how they obtained their isolate or independent DNA sequencing is done; we include such information when it is available to us). Commercially available non-kveik landrace farmhouse yeast are listed on the Landrace Yeast page.

Kveik Registry Num Yeast Lab Package Notes
Sigmund Gjernes's Voss 1 Omega Yeast Labs Voss Kveik OYL-061 Single strain isolate. Omega Yeast Labs and The Yeast Bay independently isolated one of the strains from the Voss Kveik. It is not known if these are the same strains, or which NCYC strain they correspond to. However, they are thought to be similar in their flavor profile [38].
Sigmund Gjernes's Voss 1 The Yeast Bay Sigmund's Voss Kveik (WLP4045 from White Labs) Single strain isolate. Potentially the same as the Omega Yeast Labs Voss strain; see the Sigmund Gjernes's Voss entry for Omega Yeast Labs Voss Kveik OYL-061 above [38].
Sigmund Gjernes's Voss 1 Mainiacal Yeast The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Sigmund Gjernes's Voss 1 Escarpment Laboratories Voss Kveik Single strain isolate.
Sigmund Gjernes's Voss 1 Sleight Beer Lab Gebo Nordic Yeast Pitch Single strain isolate; sold dried.
Sigmund Gjernes's Voss 1 Imperial Yeast Loki A single strain isolate; likely to be the same isolate as the Omega Voss Kveik OYL-061 isolate [39].
Sigmund Gjernes's Voss 1 East Coast Yeast ECY43 Nordic Farmhouse Single strain isolate.
Sigmund Gjernes's Voss 1 Fermentum Mobile (Poland) FM53 Voss kveik Single strain isolate.
Sigmund Gjernes's Voss [40] 1 Inland Island Yeast Laboratories INIS-441 Norwegian Farmhouse Single strain isolate
Sigmund Gjernes's Voss 1 Community Cultures Yeast Lab The Fruity Norwegian (formerly called "Kveik", and "The Fruity Norwegian" was formerly the brand name for a different unknown kveik culture that the company removed from market [41]) Single strain isolate
Sigmund Gjernes's Voss 1 Propagate Lab MIP-340 Voss Kveik Isolate Single strain isolate.
Sigmund Gjernes's Voss 1 Yeastlab (Brazil) YLB1010 - Kveik 01 Single strain isolate [42].
Sigmund Gjernes's Voss 1 Lallemand Brewing Voss Kveik Ale Yeast Single strain isolate [43]. See this MTF comment from a Lallemand representative regarding cell counts in this product.
Rivenes 2 Mainiacal Yeast Dried Kveik - Rivenes Dried format. Rivenes has the classic orange character that many Kveik has. It does have one Lactobacillus strain in the mix, but is intolerant of 10 IBU. This Lactobacillus complements the orange notes [44].
Stein Langlo's Stranda 3 Omega Yeast Labs HotHead Ale OYL-057 Single strain isolate (only one strain was revived by NCYC).
Stein Langlo's Stranda 3 Mainiacal Yeast Dried Kveik - Stranda The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Stein Langlo's Stranda 3 Propagate Lab Stranda Single Isolate Single strain isolate (only one strain was revived by NCYC).
Terje Raftevold's Hornindal 5 Escarpment Laboratories Hornindal Kveik Blend Two strains isolated from the original culture.
Terje Raftevold's Hornindal 5 Escarpment Laboratories July 2020: Hornindal Farm Kveik The full, unpurified (no microbes isolated or removed) culture; contains lactic acid bacteria. Potentially a one-time release under the lab's monthly "Kveik Ring" kveik release [45]
Terje Raftevold's Hornindal 5 Mainiacal Yeast The full, unpurified (no microbes isolated or removed) culture; contains lactic acid bacteria. Limited availability.
Terje Raftevold's Hornindal 5 Omega Yeast Labs Hornindal Kveik Original culture, but "purified" to remove the lactic acid bacteria.
Terje Raftevold's Hornindal 5 Omega Yeast Labs OYL-071 Lutra™ Kveik Single isolate from the original Hornindal kveik; characterized as being a "shockingly clean" strain [46][47].
Terje Raftevold's Hornindal 5 Propagate Lab MIP-342 Kveik Hornindal The full, unpurified (no microbes isolated or removed) culture.
Terje Raftevold's Hornindal [48] 5 Bio4 (Brazil) SY081 Norwegian Kveik Single strain isolate [49].
Terje Raftevold's Hornindal 5 The Yeast Bay Hornindal Kveik Single isolate; characterized as "stone fruit and tropical esters".
Terje Raftevold's Hornindal 5 Imperial Yeast A46 Bartleby Single isolate; characterized as "pineapple, apricot and peach aromas".
Lærdal 6 Mainiacal Yeast Dried Kveik - Laerdal The full, unpurified (no microbes isolated or removed) culture; contains lactic acid bacteria. Sold dried. Limited availability.
Lærdal 6 Escarpment Laboratories Lærdal Kveik Single strain isolate. Potentially a one-time release under the lab's monthly "Kveik Ring" kveik release [45].
Hans Haugse's Granvin 7 Mainiacal Yeast The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Sigurd Johan Saure's Tormodgarden 8 kveiktraining.com Dried kveik #8 Tormodgarden / Saure Sold by the farmhouse directly by Saure. 1 plastic bag containing approximately 15 grams of dried kveik #8 ("#8" refers to the Farmhouse Yeast Registry number). There might be some residue of the brown paper used for drying, but Saure says that it will not affect the fermentation, its all been sanitized before drying the kveik [50].
Sigurd Johan Saure's Tormodgarden 8 Escarpment Laboratories Tormodgarden Kveik Potentially a one-time release under the lab's monthly "Kveik Ring" kveik release [45].
Ebbegarden, Stordal 9 Sleight Beer Lab Ehwaz Nordic Single strain isolate; sold dried.
Ebbegarden, Stordal 9 Escarpment Laboratories Ebbegarden Kveik Blend Two strains isolated from Ebbegarden [51].
Ebbegarden, Stordal 9 Mainiacal Yeast Dried Kveik - Ebbegarden The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Ebbegarden, Stordal 9 Propagate Lab MIP-343 Kveik Ebbegarden
Framgarden, Stordal 10 Mainiacal Yeast The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Framgarden, Stordal 10 Sleight Beer Lab Fehu Nordic Single strain isolate.
Framgarden, Stordal 10 Propagate Lab MIP-344 Kveik Framgarden
Framgarden, Stordal 10 The Yeast Bay Framgarden Kveik Single isolate; described as "melon and cantaloupe esters".
Framgarden, Stordal 10 Escarpment Laboratories Framgarden Kveik Blend of multiple isolates from the original Framgarden [52]. Potentially a one-time release under the lab's monthly "Kveik Ring" kveik release [45].
Framgarden, Stordal 10 Imperial Yeast A36 POG Single isolate; described as "tropical fruit aromas".
Lida 11 Mainiacal Yeast Dried Kveik - Lida The full, unpurified (no microbes isolated or removed) culture with a strain of Lactobacillus. Limited availability.
Lida 11 The Yeast Bay Lida Kveik Single isolate; characterized as "apricot, stone fruit, and white grape esters".
Lida 11 Propagate Lab MIP-355 Kveik Lida
Årset 13 Mainiacal Yeast Dried Kveik - Årset The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Årset 13 Escarpment Laboratories Årset Kveik Blend Contains multiple inter-related strains; see this explanation from Richard Preiss. Sold as sourced by Jakob Årset, on the farm Årset in Eidsdal, Norway. The overall flavour profile is similar to the Hornindal Kveik Blend, but this blend exhibits a broad temperature range (we have heard of sub-15ºC) and tolerates acidic wort quite well.
Nornes 15 Mainiacal Yeast Dried Kveik - Nornes The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Nornes 15 Propagate Lab MIP-345 Kveik Nornes
Midtbust, Stordal 17 Mainiacal Yeast Dried Kveik - Midtbust The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Midtbust, Stordal 17 The Yeast Bay Midtbust Kveik Single isolate; characterized as "restrained ester profile".
Midtbust, Stordal 17 Propagate Lab MIP-347 Kveik Midtbust
Nystein 19 Mainiacal Yeast Dried Kveik - Nystein The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Espe 20 Mainiacal Yeast Dried Kveik - Espe The full, unpurified (no microbes isolated or removed) culture. Contains Lactobacillus reportedly tolerant of up to 9 IBU. Described as spice rum/cognac character along with apricot and peach notes. Recommended fermented on the cooler side between 60-85°F. Limited availability.
Espe 20 Omega Yeast Labs OYL-090 Espe Kveik Single strain isolate.
Tomasgard 21 Mainiacal Yeast Dried Kveik - Tomasgard The full, unpurified (no microbes isolated or removed) culture, including a hop tolerant Lactobacillus. Limited availability.
Stalljen 22 LevTeck (Brazil) Seljeset Kveik The full, unpurified (no microbes isolated or removed) culture [53].
Stalljen 22 Escarpment Laboratories Seljeset Kveik Four isolates from the original culture. Reportedly one of the fastest fermenting kviek. Potentially a one-time release under the lab's monthly "Kveik Ring" kveik release [45].
Stalljen 22 Propagate Lab MIP-348 Kveik Stalljen
Halvorsgard 28 Escarpment Laboratories Halvorsgard Two isolates from the original kveik. Contains POF+ trains, strong fruity aromas wiht a light "baking spice". Potentially a one-time release under the lab's monthly "Kveik Ring" kveik release [45].
Ner-Saure 31 Mainiacal Yeast Dried Kveik - Ner-Saure Dried format. Characterized as having a burnt citrus character and fresh baked bread notes. This culture also has a Lactobacillus in that that is a bit more tolerant around 12 IBU [54].
Wollsæter 35 Mainiacal Yeast The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Aurland 38 Propagate Lab MIP-341 Kveik Auland The full, unpurified (no microbes isolated or removed) culture. May contain bacteria.
Aurland 38 Mainiacal Yeast Dried Farmhouse - Auland The full, unpurified (no microbes isolated or removed) culture. Potentially POF+, and contains a species of Candida.
Skare 41 Mainiacal Yeast Dried Kveik - Skare The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Skare 41 Escarpment Laboratories Skare kveik Pronounced "scar-uh". Blend of 3 isolated strains from skare kveik. Potentially a one-time release under the lab's monthly "Kveik Ring" kveik release [45]
Opshaug 43 Mainiacal Yeast Dried Kveik - Opshaug The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Opshaug 43 White Labs WLP518 Single strain isolate [55].
Opshaug 43 Propagate Lab MIP-352 Osphaug
Jordal 44 Mainiacal Yeast Farmhouse - Jordal The full, unpurified (no microbes isolated or removed) culture. Limited availability. It contains a mix of 3 Saccharomyces cerevisiae strains and 2 hop intolerant (tolerates 9-10 IBU) Lactobacillus strains.
Hovden 48 Mainiacal Yeast Dried Kveik - Hovden The full, unpurified (no microbes isolated or removed) culture. Limited availability.
Ebbegarden, Framgarden, Lida, Raftevold gård, and Wollsæter (blend) Mainiacal Yeast Kveik the World Blend Kveik blend dedicated to the late William Holden who created the Kornolfetsival to showcase kveik and helped trade kveik with brewrs outside of Norway. Each selected kveik was collected by William Holden. A portion of the proceeds from each sale will go to William's family. Contains hop intolerant strains of Lactobacillus (5-10 IBU will inhibit sour flavor).
Hornindal, Voss, Ebbegarden, and Årset (blend) Escarpment Laboratories Kveik The World Blend Different than the Mainiacal culture of the same name. This was a promotional blend that was handed out for free at HomebrewCon 2019, but the company might hand it out again at future events [56].
Unknown Bootleg Biology OSLO Single strain isolate. Isolated from Eld & Tid's house culture which is a mix of multiple kveik cultures from Hornindal (thus the exact original kveik that this isolate comes from is not known) [57]. See this MTF thread on speculating which kveik this isolate could be from. It has been confirmed via ITS sequencing that this strain is within the kveik family but not which kveik culture it comes from [58].

See also:

Unknown Bootleg Biology AURORA Single strain isolate. Isolated from one of the kveik cultures from Hornindal (the specific kveik culture from Hornindal, of which there are a few, is unknown to Bootleg Biology) [57].
Unknown Imperial Yeast A44 Kveiking A blend of three isolated strains. The origin of the three strains is proprietary [59].
Unknown (blend) Mainiacal Yeast Dried Kveik Blend - Juggernaut A blend of 6 different Saccharomyces cerevisiae strains isolated from 6 different kveik. Limited availability.
Unknown (blend) Mainiacal Yeast Dried Kveik Blend - Berserker A blend of 3 different Saccharomyces cerevisiae strains isolated from 3 different kveik. Limited availability.
Unknown Propagate Lab MIP-354 Oslo Most likely the same as the Bootleg Biology OSLO.
Unknown WHC Lab (Ireland) Ubbe Clean "lager-like" taste and aroma. Single strain isolated from the Hornindal region in Norway [60]. This is reported to be the same strain as Bootleg Biology's OSLO product [61].
Unknown WHC Lab (Ireland) Bjorn Single strain isolate from the Hornindal region in Norway. Characterized as fruity [60].
Unknown WHC Lab (Ireland) Lagertha Single strain isolate from the Stranda region in Norway [60]. Editor's note: this is likely the same strain as Omega HotHead.
Unknown WHC Lab (Ireland) Odin Lightly fruity; ferments in the lower 20's °C [60]. Most likely a single strain isolate.
Unknown WHC Lab (Ireland) Ragnar Single strain isolate from the Voss region in Norway [60]. Editor's note: this is likely the same strain as Omega Voss.
Unknown WHC Lab (Ireland) Valkryie A yeast strain isolated from a kviek isolate from Ebbegarden region in Norway (most likely #9 on the registry [60].

Landrace Yeast In Other Countries

There are farmhouse yeasts in other countries and Norway that have survived for generations, similar to kveik, but are genetically distinct from kveik. Since the term "kveik" refers to just Norwegian farmhouse yeast, the term "landrace yeast" has been proposed to refer to farmhouse yeasts as a category of yeast. Non-kveik landrace yeast includes yeasts from Lithuania and Russia such as Simonaitis, Rima, and Jovaru Alus, as well as the Norwegian farmhouse yeast Muri which is not genetically related to any kveik strains.

See Landrace Yeast for more information and commercially available cultures.

Specific Kveik Culture Information

See the Farmhouse Yeast Registry maintained by Lars Garshol for more complete and updated information on individual kveik cultures.

Sigmund Gjernes's Voss Kveik

The NCYC found that a sample of Sigmund Gjernes's kveik was made up of three strains of S. cerevisiae. No bacterial contamination was found. DNA fingerprinting found the strains to be closely related [62]. See Larsblog Kveik analysis report for more information.

Tips For Use

Ebbegarden, Stordal

This kveik comes from Jens Aage Øvrebust, and was collected by William Holden. Jens originally brewed raw ale, but started boiling the wort because his beer became sour now and then. Pitch at 28C, harvest yeast from the top after a couple of days. Prefers not to let the yeast go over 30. Usually ferments 4-6 days. Sent to NCYC and NTNU, but no results yet. Jens usually ferments down to an SG of 1010, because he doesn't want the beer sweet. He says the yeast has always been in the valley as far as he knows.

Appears to have an unusual relationship with hops, so beware that this yeast may accentuate the hop bitterness in your beers. Jens says he only dry-hops himself. Richard Preiss from Escarpment Laboratories reported that sensory data on how bitter beer tastes with Ebbegarden kveik versus other yeast strains (Hornindal kveik and Conan strain) is that it produces a slightly more bitter beer, but the effect is not big [64].

Relevant Larsblog Posts and MTF Content

MTF "The Podcast"

Kveik

Raw Ale

  • Raw ale - Definition of "raw ale", and the methods used to brew it in historical and traditional farmhouse brewing.

Norwegian Farmhouse Ale (Maltøl)

Farmhouse Ale in Other Countries

Kornølfestival

There is an annual festival created by the late William Holden celebrating the cultural traditions of European farmhouse brewing called the Kornølfestival. The festival is held in Hornindal, Norway in October with bus and hotel accommodations for visiting attendees.

  • Chop n Brew interview with Lars Marius Garshol and Stig Jarle Seljeset about the festival:

Videos

  • Traditional farmhouse malting and brewing, from Aurland, Sogn (audio is in Norwegian, but the imagery is still worthwhile if you do not understand Norwegian):
  • Brewing with the elusive Hornindal-strain, done old school, no boiling, 2 days fermenting:
  • Ivar A. Geithung making farmhouse ale at Vasstrond'e Småbryggjarlaug in Voss, Norway:
  • RåØl (Raw Beer) Brewday with John Palmer at EIK og TID:
  • Presentation by Lars Marius Garshol (in Norwegian):
  • Omega Yeast Labs presentation on farmhouse brewing and using kveik:
  • Presentation on kveik with Lance Shaner from Omega Yeast Labs, Damian Fagan, co-founder of Almanac Beer Co, and Chris Cohen:
  • First ever North America presentation on kveik and farmhouse ales by Lars Marius Garshol at Burnt City Brewing in Chicago, 2019:
  • Norwegian farmhouse brewer Ivar Geithung documents the brewing and fermentation of a traditional farmhouse brew that takes inspiration from other areas (Chop and Brew video; part 1 and 2):

See Also

Additional Articles on MTF Wiki

External Resources

References

  1. ↑ Bab.la Dictionary. Retrieved 01/21/2016.
  2. ↑ Ivar Geithung. Chop And Brew Youtube video. 09/21/2019. Retrieved 09/24/2019.
  3. ↑ [https://www.crowdcast.io/e/n2kbq0af Lars Marius Garshol. Presentation for Brewers Association. May 2020. Retrieved 05/18/2020
  4. ↑ <Lars Marius Garhol and Stig Bernsten. Milk The Funk Faecbook group thread on how to pronounce 'kveik'. 05/14/2019.
  5. ↑ Sveinung Marvik and Lars Marius Garshol. Kveik Facebook group. 01/03/2018.
  6. ↑ 6.0 6.1 6.2 Lars Marius Garshol. Milk The Funk Facebook group reply on the meaning of the word "kveik". 12/29/2016.
  7. ↑ "Kveik" - what does it mean?. Lars Garshol. Larsblog. 10/29/2017. Retrieved 10/29/2017.
  8. ↑ 8.0 8.1 Richard Preiss. Milk The Funk Facebook group thread on kveik. 06/19/2018.
  9. ↑ "Analysis of farmhouse yeast (kveik)." Larsblog. Lars Marius Garshol. 09/06/2016. Retrieved 09/06/2016.
  10. ↑ 10.0 10.1 10.2 Kveik: Norwegian farmhouse yeast. Larsblog. 11/07/2013. Retrieved 01/14/2016.
  11. ↑ Lars Marius Garshol. "The juniper mystery". Larsblog blog. 02/02/2017. Retrieved 12/13/2018.
  12. ↑ Maltøl, or Norwegian farmhouse ale. Larsblog. 10/11/2016. Retrieved 01/14/2016.
  13. ↑ The Microbiology of Malting and Brewing. Nicholas A. Bokulich, Charles W. Bamforth. 2013. DOI: 10.1128/MMBR.00060-12.
  14. ↑ 14.0 14.1 14.2 14.3 14.4 14.5 14.6 Traditional Norwegian Kveik Are a Genetically Distinct Group of Domesticated Saccharomyces cerevisiae Brewing Yeasts. Richard Preiss, Caroline Tyrawa, George van der Merwe, Kristoffer Krogerus, Lars Marius Garshol. 2018.
  15. ↑ Norwegian farmhouse ale. Larsblog. 10/27/2013. Retrieved 01/14/2016.
  16. ↑ 16.0 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 How to Brew with Kveik. Lars Marius Garshol and Richard Preiss. MBAA Technical Quarterly, 2018 Q4.
  17. ↑ Varying opinions from MTF members, including Norwegians. Milk The Funk Facebook group chat about putting 'kveik' and where it is from on beer labels for mixed fermentation sour beers. 01/28/2019.
  18. ↑ Lars Marius Garshol. Kveik facebook group thread on kveik terminology. 11/03/2018.
  19. ↑ 19.0 19.1 19.2 Richard Preiss and Lars Garshol. Milk The Funk post about the subtle differences in strains in some kveik cultures. 04/04/2019.
  20. ↑ 20.0 20.1 20.2 20.3 20.4 20.5 Nadia Marlen Aasen. Growth, metabolism and beer brewing with kveik. Master's Thesis. Norwegian University of Life Sciences. 2020.
  21. ↑ Richard Preiss. Milk The Funk Facebook thread on kveik and the STA1 gene. 01/03/2018.
  22. ↑ Richard Preiss. Milk The Funk Facebook group comment about the two families of kveik yeast. 09/13/2018.
  23. ↑ Richard Preiss, Ingo Janssen, and Dan Pixley. Milk The Funk Facebook group on not treating kveik as "super yeast". 07/24/2019.
  24. ↑ Sensory data on kveik strains shared by Richard Preiss on MTF. 09/15/2016.
  25. ↑ Richard Preiss. Escarpment Labs blog post, "Crispy brewing with kveik: mind the pH gap." 11/26/2019. Retrieved 11/26/2019.
  26. ↑ Richard Preiss. Milk The Funk Facebook thread on kveik resulting in a lower pH for final beer. 11/26/2019.
  27. ↑ Richard Preiss. Milk The Funk Facebook thread on Escarpment Labs recommended kveik pitching rates. 07/27/2019.
  28. ↑ Adi Hastings. Milk The Funk Facebook thread on under-pitching kveik and potential off-flavors. 07/27/2019.
  29. ↑ Mark Schwarz. "Norwegian Kveik Strains and More with Omega Co-Founder Mark Schwarz" at Texas Brewing Inc. 05/14/2019. Retrieved 07/27/2019.
  30. ↑ Richard Preiss. Milk The Funk Facebook post on FAN requirements for kveik. 06/30/2019.
  31. ↑ Richard Preiss. Milk The Funk Facebook group thread on vitamin requirements for kveik. 08/03/2019.
  32. ↑ Justin Amaral. Milk The Funk Facebook group thread about lactic acid bacteria in kveik cultures and sensitivity to IBU. 06/05/2018.
  33. ↑ "Scandinavian Yeast Rings - the curious case of the Twisted Torus". Susan Verberg. 2019.
  34. ↑ Lars Marius Garshol. Twitter feed. 04/16/2019.
  35. ↑ Lars Marius garshol. Milk The Funk Facebook group post about using a kveik ring. 2017.
  36. ↑ Justin Amaral. Milk The Funk Facebook group post on kveikstokk and drying Brettanomyces. 08/16/2018.
  37. ↑ Dr. Bryan Heit. Sui Generis Blog post about dried kveik viability over time. 08/28/2019.
  38. ↑ 38.0 38.1 Conversation with Lance Shaner and Lars Marius Garshol on MTF. 01/04/2016.
  39. ↑ Imperial Yeast. Facebook post on Imperial Yeast Facebook page. Retrieved 07/12/2019.
  40. ↑ Private correspondence with Inland Island sales staff by Dan Pixley. 04/05/2019.
  41. ↑ Mara Louise Young. Milk The Funk Facebook thread on Community Cultures Kveik cultures. 10/21/2019.
  42. ↑ Yeastlab (Brazil) website. Retrieved 10/18/2019.
  43. ↑ Robert Percival. Twitter. 11/06/2019. Retrieved 11/24/2019.
  44. ↑ "Dried Kveik - Rivenes". Mainiacal Yeast website. Retrieved 10/25/2020.
  45. ↑ 45.0 45.1 45.2 45.3 45.4 45.5 45.6 Escarpment Labs website, 09/10/2019. Retrieved 09/10/2019.
  46. ↑ Omega Labs website. "Announcing Lutra™ Kveik, A Shockingly Clean Kveik." Retrieved 06/14/2020.
  47. ↑ Omega Labs Facebook page comment on Lutra source kveik. 10/14/2020.
  48. ↑ Breno B Jorge. Correspondance with Bio4 staff; reported in Milk The Funk Facebook group. 10/22/2019.
  49. ↑ Bio4 website. Retreived 10/18/2019.
  50. ↑ Kveik Training website. Retrieved 11/10/2019.
  51. ↑ Chris Saunders. Milk The Funk Facebook post on Escarpment Labs Ebbegarden. 04/04/2019.
  52. ↑ Private correspondence with Richard Preiss by Dan Pixley. 05/27/2020.
  53. ↑ LevTeck website. Retrieved 10/18/2019.
  54. ↑ "Dried Kveik - Ner-Saure". Mainiacal Yeast website. Retrieved 10/25/2020.
  55. ↑ Allen Stone. Image of a White Labs poster. 04/14/2019.
  56. ↑ Richard Preiss. Milk The Funk Facebook thread on Escparment Labs "Kveik the World blend". 08/20/2019.
  57. ↑ 57.0 57.1 Jeff Mello. Personal correspondence with Dan Pixley. 03/07/2019.
  58. ↑ Richard Preiss. Milk The Funk post on ITS sequencing OSLO. 08/-02/2019.
  59. ↑ Imperial Yeast Facebook post. 06/27/2019.
  60. ↑ 60.0 60.1 60.2 60.3 60.4 60.5 WHC website. Retrieved 08/02/2019.
  61. ↑ Correspondance with Philip Nutt. Milk The Funk Facebook group post on WHC Labs' Ebbe kveik strain. 01/14/2020.
  62. ↑ Analysis of Sigmund Gjernes Voss yeast sample for Lars Marius Garshol, RÆLINGEN NORWAY. September 2014. Retrieved 01/20/2016.
  63. ↑ Lars Marius Garshol and Richard Preiss on Voss alcohol tolerance. Milk The Funk Facebook group. 08/04/2017.
  64. ↑ Richard Preiss. Milk The Funk Facebook group thread on the bitterness produced by Ebbegarden kveik. 12/04/2018.
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