Challenger Approaches: Enter London III & Kveik Voss

Updated: Apr 7, 2019

Hello all, I am Jeff the Lab Guy here at O’so Brewing Co. I manage our yeast/bacteria program, and today we are going to share some cool stuff we are working on in our yeast program. In this post, we are going to keep it simple and explain the changes that we are making to the yeast in our core lineup of beer. With the intent to post more technical posts in the future, detailing specific concepts pertaining to our yeast management.

Yeast starters being prepped for pilot brews

Yeast are microorganisms that are essential to the brewing process. There are many kinds of yeast, and many have beer brewing application either alone or with bacteria to produce a myriad of different styles of beer. We primarily use brewers yeast (Saccharomyces cerevisiae for ales, pastorianus for lager) for their specific fermentation qualities to produce beer. There are many strains of Saccharomyces that behave differently such as tolerating different concentrations of alcohol, enjoying specific temperature ranges, and imparting unique fermentation derived flavor profiles which are application dependent. We also work with brettanomyces a family of highly attenuating yeast with unique derived ester and phenol profiles, with many species for specific funky applications. There are many other species that have value for flavor, or encourage coexisting fermentation with our bacteria cultures such as picha.

Happy Yeast Happy Beer

To talk about yeast, we first must start at the beginning. When brewers sparge grain, it creates a product called wort which is effectively sugar water. Yeast, and the myriad of bacteria that work with with yeast, eat up the sugars produced in the brewing process, and produce alcohol and C02 as byproducts. Although the end product of beer requires hops and specialty malts in order to come to completion, Yeast is arguably the most important ingredient, as beer does not exist without it.

Chico yeast being tested for viability. Blue cells are considered non viable. 400x

For years, we utilized Chico for all ales across all styles. Chico goes by many names (US-05, American Ale, 1056) and is the most popular choice for American brewers looking for a clean yeast with a neutral flavor profile. Chico is a workhorse that produces good quality beer without off-flavors, and when managed well we can re-pitch the yeast up to 10 generations before viability starts to fall off. In the past, we used Chico in all the our core lineup of beers and many of our big stouts. While in Hazy/Juicy IPA’s (Hop Debacle, Hop Snack, Colada-ral Damage, ect) we deviated with the use of London III which we will touch on later. While Chico is a great, all around yeast, we were not getting the flavor profile we desired in many of our beers with it favoring only the west coast IPA’s in our portfolio (Hop Dinger, Hop Whoopin).

London III was isolated from a brewery in London (go figure) and is a great choice for traditional British styles, malt forward beer and NEIPA’s due to its fruity ester profile, high flocculation (aggregates of yeast dropping out of suspension), and soft mouthfeel which enhances malt profile. London III is our choice for maltier beers (Night Rain, Rusty Red) and many of our NEIPA (Hop Debacle, Hop Debauchery, Colada-ral Damage, ect) offerings. We have experience playing with Lab pitches of London III to ferment our NEIPA’s. The additional fermentations of Night Rain and Rusty Red will allow us wort stocks for cone-to-cone pitching to manage London III where otherwise utilized in beer that is dry hopped at heavy rates early in the fermentation process making repitching off the cone untenable.

Geraniol Biotransformation Pathway via Ale and Lager Yeast ( King and Dickenson . 2003)

The benefits of London III are not limited to mouthfeel and flocculation. London III can utilize a mechanism called biotransformation used as a catch all term for when a molecule changes to another molecule mediated by or within a living organism. Our biotransformation for the purposes of our brewing application involves monoterpene alcohols derived from hops which through a series of steps is “biotransformed” from a molecule that denotes certain sensory characteristics, which are typically thought of as conserved in the hop flavor profile, into a molecule which not only denotes an entirely different sensory profile, but is preferred for a specific application which in our case is NEIPA.

9 out of 10 Hazy Bois prefer London III

With the selection of London III yeast we can add dry hops that would denote herbaceous, spicy, floral notes into molecules that smell and taste of citrus, stone fruit, tropical fruit, and deep perfume. (K. Haslbeck et al., 2018) Through this application of dry hopping during active fermentation, we can create solutions denoting fruit flavor profiles which do not exist naturally in these hop strains. This opens up hop selection, and allows us through repetition to dial in the juicy NEIPA with batch to batch consistency utilizing this yeast-hop relationship.

London III banked for propagation

London III is a better choice then Chico for our applications in malt-forward beers and NEIPA. What about everything else? After trial batches and pilots across many yeast strains, we came to a solution that takes a new-school approach to an old school ancestral yeast - Kveik. Kveik is a Norwegian dialect word translating to “yeast” that denotes a genetically diverse group of landrace yeast. It is not a style. IT IS NOT A STYLE.

Hothead Slurry under 1000x Oil Immersion

Talking about kveik is impossible without mentioning Lars Marius Garshol, who made kveik a household name within the brewing consciousness collective. (Shoutout to Milk The Funk for mediating discourse, and compiling information) These yeasts very well may have died out without this intervention by Garshol who introduced many cultures obtained from traditional norwegian farmhouse brewers to American brewers and yeast labs. These were typically mixed cultures also containing bacteria, and the isolation of the yeast and subsequent work creating lab propagated clean pitches and introduction to commercial brewing helps to preserve the yeast for future brewing generations.

Omega Voss being tested for viability cropped from Big 2.0 400x

We are utilizing Voss Kveik from Omega Yeast Labs in all other ales that do not benefit from London III. Voss is a beast. It will ferment wort quickly and attenuates dry. It produces lovely orange citrus esters and its happy temperature range are much higher than most non-kveik sacch strains allowing us to freeride the beer in the fermentation vessel achieving temperatures of up to 98F getting increased orange ester production for fruity ales like Big O, without off flavors. If we want less ester presence we can simply ferment at 68F like we would Chico for a longer fermentation that results in a cleaner profile. Since these yeasts were isolated from mixed cultures, we know they play well with bacteria and can handle low pH, and produces favorable esters complimenting the tart lacto flavor profile making Voss a great choice for kettle soured ales. Voss flocs so hard, making it a candidate for a wide range of styles from NEIPA, dry hopped witbier, kettle sour/wild ale, and whatever Big O is. It's truly a fantastic yeast to work with from both a brewing, and yeast management perspective.

Sampling all the new yeast

We understand this is a lot of change between switching yeast strains, and moving into cans. Bear with us. We promise this entire endeavor will make our beer better than ever. We are excited for the new challenges and opportunities to produce and package quality beer that both excites us, and makes us proud to continue this tradition of freestyle brewing.

We can’t wait to share more! -Jeff The Lab Guy

TLDR: We’ve done plenty of testing and made the decision to switch yeasts on many of our beers. This will result in better flavor profiles and flavors, along with better mouthfeel. Please bear with us as we make these changes!

*If you are interested in Kveik history, or traditional use I highly recommend checking out Larsblog on beer, and the Milk the Funk wiki on Kveik. Both are excellent resources which act as a wealth of information on the topic to brewers and enthusiasts alike. Kveik will be covered heavily in future posts.

Shoutout to Danny B, and Mark S. for help editing as well as the entire O'so team for making these endeavors a reality!


King, A. J. and Dickinson, J. (2003), Biotransformation of hop aroma terpenoids by ale and lager yeasts. FEMS Yeast Research, 3: 53-62. doi:10.1111/j.1567-1364.2003.tb00138.x

Korbinian Haslbeck, Stefan Bub, Kristina Kamp, Maximilian Michel, Martin Zarnkow, Mathias Hutzler and Mehmet Coelhan, The influence of brewing yeast strains on monoterpene alcohols and esters contributing to the citrus flavour of beer, Journal of the Institute of Brewing, 124, 4, (403-415), (2018)

Lars Garshol on, "kveik-what does it mean?"

Milk The Funk wiki 2019, ‘Kveik’, viewed 02, March 2019 <>

Takoi, K. , Itoga, Y. , Koie, K. , Kosugi, T. , Shimase, M. , Katayama, Y. , Nakayama, Y. and Watari, J. (2010), The Contribution of Geraniol Metabolism to the Citrus Flavour of Beer: Synergy of Geraniol and β‐Citronellol Under Coexistence with Excess Linalool. Journal of the Institute of Brewing, 116: 251-260. doi:10.1002/j.2050-0416.2010.tb00428.x


O'so Brewing Company

3028 Village Park Dr

Plover, WI


(715) 254-2163

Copyright © 2020 O'so Brewing Company LLC