Are kveik thermophilic or thermotolerant: fermentation rates part 2
Updated: Feb 3, 2021
Introduction:
This is a continuation of "Is kveik thermophilic or thermotolerant: fermentation rates part 1". Please read part 1 if you haven't yet.
The purpose of the 2nd part is to compare kveik fermentation kinetics at high temperatures (35-39ºC) and room temperature (~20-22ºC) to the fermentation kinetics of "typical" non-kveik ale yeast. In part 1, we found out that some kveik are "thermophilic" and not just thermotolerant (i.e. perform better at 35-39ºC than 22ºC). The question we're asking now is basically, are kveik faster than typical ale yeast at typical pitching temps (~22ºC)?
For me, as in part 1, the goal is not to achieve the fastest fermentation. It is a question of kinetics and evolution - are kveik distinct in activity from typical ale yeast at "mesophilic" temperatures? Some kveik have a temperature optimum at high temps (>35ºC), but are they still faster than typical ale yeast at normal pitching/fermentation temperatures?
Methods:
The methods are outlined in part 1, so read that if you haven't yet. Basically, I made 23 batches of beer, where I tracked gravity and CER (CO2 evolution rate) over time. All of the kveik batches in part 1 were a simple pilsner/vienna/munich malt grist (details in part 1) so the malt bills for those were the same. For the other 15 non-kveik batches, the malt bill was not always the same - I didn't want to drink 200+ L of the same beer.
-The mashing temp was always 65ºC
-Always mashed for 60 min at pH of ~5.45
-Always mashed out at 78ºC for 1 min prior to batch sparge
-60 min boil always
-bittering hops were always the same, but I changed the aroma hops sometimes, none of the beers were dry hopped
-I never used dextrin malts
-I always kept the batch size and volumes the same
-Starting gravity ranged from 1.044-1.052 for 14 of the 15 batches
-pitching rates were always kept standard (1 liquid pouch per 5 gallons or 1 pack 11g per 5 gallons)
-Temperature maintained using a fridge fermentation chamber for the FV coupled to an inkbird and heating pad. This allows temperature control of +/- 0.5ºC from 4ºC to 41ºC.
-For the non-kveik yeasts, I usually fermented in the middle of the manufacturer's recommended temperature range (for example, M44 West Coast has a recommended range of 18-23ºC, so I went with 21ºC).
Results:
Figure 1: Time to finish fermentation, gravity over time, CER over time for 7 yeasts incubated at around room temperature (18-22ºC)
Figure 1 shows the fermentation kinetics for 7 yeasts incubated around room temperature (18-22ºC). The left most panel is the time to finish fermentation (the cutoff to determine this is explained in part 1).
Lower time to finish fermentation = faster fermentation.
The centre panel shows the gravity trends over time, and the right panel is the CER trend over time.
A) The fastest yeast to finish fermentation at ~room temp is M15 Empire Ale from Mangrove Jack's. This yeast is an absolute monster, taking an OG of 1.050 to terminal gravity in just 40 hours at 18ºC.
Just a reminder here that the "time to finish" in this case is NOT when the fermentation hits expected FG. It is a more comprehensive measure (see part 1 for explanation) that considers metabolic activity (assessed by CER trends) and yeast "cleanup" time. So the "time to finish" is not equivalent to the time I measure the expected FG.
B) The 2nd fastest is Lallemand Nottingham ale yeast - finishing the fermentation (OG 1.046) to terminal gravity in 62 hours at 20ºC.
C) Lallemand Voss kveik is the 3rd fastest (at 22ºC) and not far behind Nottingham.
D) Omega Lutra kveik and Hornindal kveik blend are the slowest performers (22ºC), taking about 88-96 hours to finish, though Lutra kveik is not far behind M44 West Coast Ale.
Figure 2: Max gravity points per minute activity (MGPPM) and max CER (CO2 evolution rate) for 7 yeasts at around room temperature (18-22ºC)
Figure 2 is a summary of the maximum fermentation performance of 7 different yeasts at ~room temperature.
The left panel is maximum gravity points per minute activity (MGPPM) - the fastest rate of gravity decline (i.e. sugar fermentation).
Higher MGPPM = faster fermentation.
The right panel is the maximum CO2 evolution rate (CER). Both of these measures are instantaneous measures of fermentation activity/performance and correlate very well together.
Higher max CER = faster fermentation.
E) At ~room temperature (18-22ºC) M15 Empire Ale and M31 Belgian Tripel have the highest MGPPM and the highest max CER - indicating both have the highest peak fermentation activity.
F) Lutra, Hornindal, and Voss kveik are all in the middle of the pack at 22ºC
You may notice at this point that Voss, Hornindal, and Lutra at 22ºC have higher peak activity (in MGPPM and max CER) than M44 West Coast or Nottingham, but finish slower. This is because the tail end of the fermentation for the kveik at 22ºC is much longer; so even though their peak activity is higher it takes longer for them to finish up the fermentation at the end.
Figure 3: Time to finish fermentation, max CER, and max gravity points per minute activity (MGPPM), for 11 yeasts incubated at various temperatures (12-37ºC)
Figure 3 shows the time to finish fermentation, maximum peak CER activity, and maximum peak gravity points per minute consumption for 11 different yeasts (ten S. cerevisiae and one S. pastorianus - Fermentis Saflager w-34/70). The yeast type is indicated on the x-axis and the colours of the points correspond to the fermentation temperature.
Lower time to finish fermentation = faster fermentation
Higher max CER = faster fermentation
Higher MGPPM = faster fermentation
G) The absolute fastest fermentation was achieved by Lallemand Voss kveik at 37ºC (finishing in 32.5 hours).
-Voss is much slower at 22ºC but still performs similar to M44 West Coast Ale.
H) Omega Hornindal blend is the third fastest, but also only at 35ºC.
-Hornindal is much slower (taking 96 hours to finish) at 22ºC and somewhat slower than other typical ale yeasts at lower temperatures.
I) Omega Lutra kveik does not show exceptional kinetics, at high or low temperature. Lutra takes about the same amount of time to finish (at both 22ºC and 35ºC) as Saflager w-34/70 by Fermentis (fermented at 16ºC).
-As stated in part 1, Lutra shows signs of stress at 35ºC and is better fermented at 22ºC.
J) M36 Liberty Bell is a relatively slow ale yeast, taking a long time to finish fermentation and it has the lowest max CER.
K) The peak sugar consumption (in maximum gravity points per minute, MGPPM) is very very high for Hornindal blend, Voss, M15 Empire Ale, and M31 Belgian Tripel (a diastaticus variant)
-Hornindal and Voss kinetics and activity are very high only at 35-37ºC
L) M31 Belgian Tripel is slow because it is a diastaticus variant and the tail end of the fermentation is reaaaaally slow (see Figure 1, centre panel).
Conclusions:
-Voss and Hornindal have very high activity and exhibit fast fermentations but only at 35-37ºC
-Voss performs OK at 22ºC compared to typical ale yeasts
-Hornindal is best fermented warm - it's slow at 22ºC
-Overall fermentation kinetics of the tested kveik are not unrivalled
-Omega Lutra is best fermented cool (22ºC)
-M15 Empire Ale is a beast
-I don't see a point in using Omega Lutra for pseudo-pilsners unless you don't have temp control. w-34/70 is as fast at 16ºC as Lutra is at 22ºC
Awards:
Fastest: Voss at 37ºC
Fastest non-kveik: M15 Empire ale at 18ºC (!!!)
Fastest kveik: Voss at 37ºC
Honourable mention: Nottingham and M44 West Coast Ale at ~22ºC
Slowest ale: Hornindal at 22ºC
Slowest: Saflager w-34/70 at 12ºC