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.

Comparison of trypan-blue stained dead versus alive yeast
Dead kveik (left, blue) versus living kveik (right)

Drying Kveik – Viability at 2 Months

dyring kveik - trypan blue staining at 2 months
Trypan blue staining at 2 months. Click for full size.

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)!

6 thoughts on “Drying Kveik – Part 3 (2 Months)

  • May 10, 2019 at 12:26 PM

    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.

    • May 13, 2019 at 12:31 PM

      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.

      • May 13, 2019 at 12:34 PM

        Thanks. Will let you know how it works out.

  • April 26, 2019 at 3:30 AM

    What is the assumed pitch rate? From what little I know an acceptable kveik pitch rate is much different than ‘regular’ yeast.

    • April 26, 2019 at 12:13 PM

      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.


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