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Harvested Yeast - Good to Use?

Hello. I’m sure it’s been asked before, but want to ask again.

I have ~4-5 oz of some Hothead kveik yeast I harvested 8-10 months ago. It’s been sealed and in the frig. I was thinking of using it, but was curious if it would still be good.

My plan for now is to clean it up a bit by pouring off the liquid then adding some water and repeating until it looks ‘clean’. Next I was going to take an oz or so and making a starter with it. If the starter ‘grows’ I can assume all is good to use in an upcoming batch.

Last of all how does one estimate the number of cells? Is there a rule of thumb for no. of cells by volume?

Does my logic make sense?

Don’t clean the yeast there’s nothing to gain from that but stress for the yeast. IMO. Pour off the top liquid if you want. Making a starter is your biggest guarantee that it will take off when you pitch but really I think you will be fine pitching that particular yeast as is because it’s a surviver


Agreed about cleaning the yeast when I started I did but stopped and don’t see it making a difference. As far as a starter not necessary either because you have more than enough cells. Slurry is approximately 1 billion cells/ml. What you can do is activate the yeast slurry and pitch at high krausen and you will have 0 lag time and also know if it’s viable which it probably is if you stored it properly

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At eight months, I would definitely do a vitality/activation starter as these gentleman have suggested. Look into the shaken not stirred yeast starter process. Very easy and as stated above, it takes right off.

For a while i did wash the yeast. But for the last 2 brews i did. Just collected the yeast. Did store them in the fridge. When i did create a starter. I pour of a bit of the top layer. And created a starter. Must say. It took of like a rocket after. Pitching. Indeed good question. How many yeast cells are availble. After reusing your yeast. ?

I agree with you have enough yeast in the slurry but also about a starter. I always make a new starter with saved yeast. If it goes then you know its viable and you can smell it to see if it’s OK. Better to use a little DME and an extra day than risk the whole batch.


For a 5 gallon batch with that yeast I’d probably do a 500ml starter around 6-7pm the evening before I brew then pitch the whole thing at or near high K.

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