Drying Kveik – Part 3 (2 Months)
Two months ago I began an experiment in drying Kveik yeast for future use. At the 1 month time-point the dried kveik showed excellent viability. We’re now two months into the experiment, so its time for another viability test.
This test is straight-forward, I dried out some kveik slurry from a black IPA I made a few months ago using a cheap home dehydrator. The dried slurry is then stored in a home freezer, in a ziplock bag. Each month I take a small amount out, rehydrate it for 10 minutes in water, and then use a trypan blue stain to assess viability.
Drying Kveik – Viability at 2 Months
Viability continues to decrease at a slow rate. Viability is now at 84-88%, which is on-par with the ~8% drop in viability I observed last month.
Also consistent with last month, the yeast should decrease to 50% viability after 6 months of storage. I would guess that a 50% viability would be enough to pitch this yeast directly, without a starter. For storage longer than 6 months a starter is needed.
I don’t have enough data to calculate a maximum usable lifetime (e.g. ~1% viability). But I can make a rough estimate, based on the assumption of a 6 month half-life. If this is correct, the usable lifetime is about 39 months (3 years and 3 months)!
Hi Bryan:
Wondering what you think about my kveik drying plan. We will have several kveik culture starters from an experiment checking the aroma/taste profile we get from different kveik. Will have at least 100 ml starter left. Thinking of putting a slurry of all six on parchment papers on a slide warmer (we can control temp to 100 F) in a laminar flow hood with the air flow running. Thin layer should dry iI would think.
Roy
I think that would work very well. IMO (unsupported by evidence) a controlled and slower drying should preserve viability better than an uncontrolled, overly warm drying.
Thanks. Will let you know how it works out.
What is the assumed pitch rate? From what little I know an acceptable kveik pitch rate is much different than ‘regular’ yeast.
I’ve not worked that out yet, all I’ve done at this point is rehydrate small fragments (perhaps 0.5 cm x 0.5 cm x 0.2 cm) in water for 10 minutes and then stain the cells for viability.
I think the concensus is a “teaspoon per 5 gallons” of the dried slurry, but I’ve got no idea how many cells that works out to. In my home brewery I use very small starters (300 ml) for 20L of kveik up to 1.065 OG, and its worked well. I’ll double that for higher gravity beers.