How much washed yeast to use?

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Permalink Reply by Des Ross on July 7, 2014 at 10:55am

Hi Mark. After 3 days I would have thought the yeast would have mostly settled out of solution. I don't wash yeast but am lucky enough to have a dump valve on my conical to harvest yeast. I have often used over one litre of dense saved yeast in 25-50L batches and always ended up with great beer so if I was you I would definitely use the whole lot....you are only speeding up what nature does anyway! Like others I know, I have also dumped freshly brewed wort directly onto a full yeast cake from a batch I have previously kegged on the same day, again with great results. If I wasn't absolutely sure on the health of your yeast, I would also get a starter going 2-3 days before brew day, just to cover all your bases.

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Permalink Reply by Mark Weusten on July 7, 2014 at 11:09am

Thanks for that. I think it must be all yeast as it was a very clean ferment with no dry hop. Now dumping wort on a yeast cake from fresh beer, that sounds nice and efficient. I have a steam beer ready this weekend and may try this method. Mind you this was San Fran Lager yeast which I though wasnt particularly active so a starter may be wise with this....

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Permalink Reply by Damon Colbert on July 17, 2014 at 1:56pm

I find it takes some experience to learn what proportion of your slurry is yeast vs. trub.  You can usually tell by colour once you've washed it once or twice. I just make an estimate based on proportion of the particulate, whitish trub vs the creamy, darker yeast.

Trub will settle out starting almost immediately, and might take half an hour.  Whatever remains will be mostly yeast, but the older generations will flocc out sooner (i.e. hours to overnight) than younger ones (days).

In terms of knowing how much of the slurry is viable yeast, there are ways if you are scientifically inclined (though I don't know of any homebrewers who go this far).  Methyl blue staining will give you some indication of what proportion of your slurry is viable, but you'd need a microscope.  

Methods are below if you're interested in knowing more.

http://www.whitelabs.com/content/cell-countingviability-testing-0

http://eurekabrewing.wordpress.com/2012/11/18/yeast-basics-check-ye...

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Permalink Reply by Mark Weusten on July 17, 2014 at 3:11pm

Thanks Damon, I have an M44 and San Fran Lager second gen in the fridge. I think my biggest mistake was I didnt wash it in the fermenter and let settle for 30 mins before pouring the top off the trub. I would stir it up and straight into a container and chuck in the fridge for a few days before pouring off and adding water. Is that a fair comment of the correct procedure?

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Permalink Reply by JumpR on July 19, 2014 at 8:06am

Hi Mark I generally follow the procedure outlined here, which seems to have worked for me. 

Although I was a bit upset the other day upon discovering my washed yeast had frozen in the back of the fridge, thus cracking the glass jar and dropping yeasty goodness throughout the fridge!

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Permalink Reply by Mark Weusten on July 19, 2014 at 9:57am

Cheers for that article

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