The Search for KRISPY (clean kveik yeast)
You may have noticed some time in the last few weeks that we released a yeast called KRISPY, which is a kveik-derived blend intended for clean, crispy beers in less time than they may otherwise take with a lager or Kölsch yeast.
It's kind of an interesting story - we had originally thought that the most expressive, fruity kveik blends (such as Ebbegarden or Hornindal) would be what brewers wanted the most. However, a very clever yeast lab (Bootleg Biology) launched a yeast (Oslo) which was marketed specifically for making clean beers fast, and it took off fast.
Not wanting to steal their thunder, but still recognizing that brewers seem to really want a clean, fast, kveik yeast, we dove into our back-catalog of kveik isolates and research data to try to come up with a solution all our own.
While product development can sometimes take a long time, luckily we had notes on a number of our kveik isolates through the quick test ferments we sometimes do when we bank new yeasts. In essence what we did was scour our notes on kveik isolates for terms like "clean" or "lager-like", which helped us filter our hundreds of kveik isolates to a smaller and more manageable cohort. Thanks to feedback submitted from members of the Kveik Ring, we also had some hints that Skare Kveik had some serious potential for lager-like brews. We also had a yeast isolate from a bottle of Eik & Tid's beer, as well as the Oslo strain as controls. And trialling yeasts for lager-like beers wouldn't be complete without a lager yeast itself, so we included our Isar Lager strain, too.
| Strain Name | Origin | ITS Sequence Identity |
|---|---|---|
| Isar Lager | Commercial Strain | S. pastorianus |
| Oslo (Bootleg Biology) | Commercial Strain (Eik + Tid Brewery) | S. cerevisiae |
| Granvin 1 | Kveik Farm Culture | S. cerevisiae |
| Granvin 4 | Kveik Farm Culture | S. cerevisiae |
| Tormodgarden 2 | Kveik Farm Culture | S. cerevisiae |
| Skare 1 | Kveik Farm Culture | S. cerevisiae |
| Skare 2 | Kveik Farm Culture | S. cerevisiae |
| Eik + Tid Isolate | Bottle Dregs | S. cerevisiae |
Small-scale sensory experiment
The yeasts were propagated by inoculating one colony from a freshly grown plate (<1 week old) into 50 mL of wort. The flasks were shaken for 2 days. The flasks were then incubated at room temperature for 2 days. The flasks were cold-crashed for three days prior to decanting, cell count, and inoculation.
The wort was prepared to 1.057 SG and 25 IBU using 2-row malt and Magnum hops. 800mL of wort was dispensed into 1L glass bottles and cooled overnight. The wort was inoculated at 25 ºC to a pitching rate of 7 million cells / mL (yes, even the lager was pitched at 25 ºC and 7Mcell/mL).
Fermentation was monitored at 2 days and 8 days into fermentation, and specific gravity was recorded as well as quick flavour notes. The beers were cold crashed after 8 days total, and were packaged and carbonated by force carbonation (carbonation caps) after 6 days of cold crashing.
| Strain | SG (Day 2) | SG (Day 8) | Notes |
|---|---|---|---|
| Isar Lager | 1.028 | 1.010 | Acetaldeyhde, slight sulfur |
| Oslo | 1.026 | 1.011 | Clean, sulfur mid-ferment |
| Granvin 1 | 1.033 | 1.019 | Acetaldeyhde, clean, sulfur mid-ferment |
| Granvin 2 | 1.034 | 1.019 | Clean, sulfur mid-ferment |
| Tormodgarden 2 | 1.029 | 1.012 | Fruity, kveiky, citrus |
| Skare 1 | 1.021 | 1.012 | Clean, slightly fruity |
| Skare 2 | 1.026 | 1.014 | Clean |
| Eik + Tid Isolate | 1.024 | 1.003 | POF+, fruity |
Based on the fermentation data, the Granvin strains showed promise in terms of lager-like flavour but did not attenuate well. Interestingly, the Skare isolates fermented faster than Oslo but with a slightly higher final gravity. Note that the Eik + Tid isolate we obtained appeared to be phenolic (POF+) and diastatic, suggesting that there may be more than kveik in this brewery's house culture.
The samples were subjected to sensory analysis using quantitative descriptive analysis (QDA; what flavours are present?) and hedonics (do you like this beer?) with 11 tasters.
In terms of sensory profile, the Granvin 4 isolate seemed to be the closest to Isar, but as mentioned previously this strain underattenuated. Interestingly, we found that the two Skare isolates were quite similar to Oslo in terms of flavour profile, with none of these kveik isolates producing as much noticeable lagery sulfur to the panel, but with relatively balanced and neutral flavour profiles.
Sensory analysis results indicated that Skare 1 and Skare 2 were preferred by the panel. Given the higher preference but lower attenuation of Skare 2, we decided to try a blend of the two isolates in follow-up brews and that is how KRISPY was born.
What can I brew with KRISPY?
While we were hoping to do more in-depth testing of the blend in different styles of beer prior to launch, the ongoing Covid-19 situation made that impossible. However, we did manage to sneak in a few brews with the blend.
While KRISPY is definitely not a 1:1 match for a lager yeast, it is most definitely capable of making clean beers at elevated temperatures. In a comparative split batch American Lite Lager between 15ºC and 25ºC, we found that the 25ºC ferment was much faster (these seem to finish at about 48-72 hours), yet both beers showed a similar flavour profile. Previously we found that other kveiks like Hornindal can ferment a clean beer at cold temps (15ºC), but we had struggled to get super clean ferments at elevated temperatures with other kveiks. With KRISPY, you can let it charge ahead at 20-30ºC and yield a clean ferment in record time. It will still ferment well at higher temps, but does start to yield some tropical, ripe fruit esters above 30ºC.
KRISPY seems to reduce IBUs a bit more than most kveik, and appears to drop pH less, which may make it easier for brewers to adapt lager recipes over to the yeast. As we do more trial brews we will be able to collect and share more data on these fermentation criteria.
We're stoked to brew with KRISPY, and stoked to see what brewers come up with. Especially with the summer heat imminent, we are hoping that this product can become another useful tool for brewers who either don't have temp control or who want to be a little more eco-friendly! KRISPY can also be used to turn around clean beers quickly, which will be critical as brewers start ramping up to meet summer demand.
