Kveik is getting a lot of attention at the moment and rightly so. Is it wonder yeast or just a very special organism?
Here at MyBrewbot we thought we would have a look at what goes on in the fermentation fridge after you’ve pitched. We found some interesting results.
Pitching at the right temperature is important if you don’t have direct heat on the fermentation vessel
Once fermentation has started Kveik, left to its own devices, will send the temperature sky high. It consumes glucose at an astonishing rate and produces loads of heat
A good cooling system is imperative. In our experiment we measured heating/cooling/off pulses and found that 95% of the time the fermentation fridge was in cooling mode.
Here are some charts with data collected from MyBrewbot.
Note that after pitching, although the wort was at the target temperature, heating was required over the first 24 hours. The sooner the yeast kicks off, the less heat is required.
You can also see that at a set temperature of 30C there was a long period where few applications of either heat or cooling were needed.
However, a few heat pulses were needed to bring the wort up to temperature when we increased the set temperature to 33C. In my view just switching cooling off would have had the same result in much the same time as by this stage the yeast is generating its own heat.
Once the set temperature was reached the fermentation fridge was mostly in cooling mode.
We didn’t set a hysteresis level in the MyBrewbot controller but I think that in future I would set one at .5C. My expectation would be that even less heat would be required.
Now let’s look at what was happening in the fermentation fridge.
An ambient temperature probe was set up in a 1 litre bottle of water to measure the interior temperature of the fridge and to get some idea of the work (heat) going on.
What this chart tells us that even small pulses of heat (where the cooling is switched off) result in rapid and large variations in the ambient temperature of the fridge. The range is quite astonishing!
On average the ambient temperature swings more than 10C from a low of 30C to a high of 42C. Yet you can almost count the number of heat pulses on your fingers (and toes). The Kveik is consuming glucose and generating heat (and alcohol) at a rapid rate.
It would be interesting to see just how high the Kveik would take the temperature left to its own devices and what the finished product would taste like. Maybe that’s the next experiment!
This last chart looks at the fermentation itself in terms of the specific gravity. The original wort had a starting SG of 1061 and it had dropped to 1015 in 6 days. Pretty quick! And it’s still dropping. We are aiming for 1010 and we reckon we should be there by the weekend.
All in all a very different yeast. It operates at very high temperatures. Generates heat at an astonishing rate and requires a good cooling system. But as with all beers the proof is in the drinking and we are going to be very interested in the results of this one.