# Harvesting commercial yeast and pitching correct amount.



## eMPTy (16/4/15)

Hey guys,

So there are plenty of threads both here and elsewhere covering pitching sufficient viable yeast to a new beer for many obvious reasons.

What I could not find much on however was estimating the viability or cell count of yeast harvested from commercial bottle dregs. I've never tried harvesting yeast before and am having a bit of a go with it, possibly with an eye on using it in my next brew. Only thing is, this is a belgian style yeast and i'm looking at potentially pitching into a high OG. I realise that'll mean a large starter, what I have no ability to estimate is how large given I cannot accurately estimate yeast viability or original cell count. 

Any assistance or thoughts would be greatly appreciated.


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## gap (16/4/15)

Can you be sure the yeast in the bottle is the yeast used to actually ferment the beer??
Some Breweries use a different yeast to bottle condition their beer.
Also if the beer you are harvesting the yeast from is a high Alcohol beer the yeast, even if it is the original yeast, may well be stuffed and not viable to reculture.

These are some of the unknowns in trying to reculture yeast.


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## eMPTy (16/4/15)

gap said:


> Can you be sure the yeast in the bottle is the yeast used to actually ferment the beer??
> Some Breweries use a different yeast to bottle condition their beer.
> Also if the beer you are harvesting the yeast from is a high Alcohol beer the yeast, even if it is the original yeast, may well be stuffed and not viable to reculture.
> 
> These are some of the unknowns in trying to reculture yeast.


As far as i am aware it is the correct strain, although i am not sure i have found 100% confirmation. It is a La Trappe yeast.

How would you decide if it was viable to reculture? I have built up starters from about 100ml to 1L over almost one week and the yeast appears to have grown substantially. That said, i have yet to cold crash and pour off the top stuff, simply poured each new wort amount on top. As such i've not seen exactly how much yeast has grown.

You're right in identifying the unknowns, I guess I was just hoping there would be some info out there on trying to minimise their impact.


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## Midnight Brew (16/4/15)

This might help. When you buy a wyeast smack pack there is 100 billion cells in about 25ml of yeast. That is ofcourse pure fresh healthy yeast. So each ml is 4billion cells if it was manufactured that day. 

For your culturing I'd be safe and round down to say 2.5 or 3 billion cells per ml. So what you could do is decant into a measurement jar to get a rough estimation. Don't forget there may be some break material in you starter that flocs with the yeast.

If you have a microscope that's the most accurate way.


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## manticle (16/4/15)

If you are certain it is La trappe, buy the freshest example you can find of their lowest abv beer and build from that. Without using a microscope to count cells though, you are really only guessing as to what cell count you have. You can use calculators to get a possible indication - Mr malty, brewersfriend.com etc have a couple.


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## eMPTy (16/4/15)

manticle said:


> If you are certain it is La trappe, buy the freshest example you can find of their lowest abv beer and build from that. Without using a microscope to count cells though, you are really only guessing as to what cell count you have. You can use calculators to get a possible indication - Mr malty, brewersfriend.com etc have a couple.


I've had a look at some of those calculators. I think I may just use the yeast i have built up so far with maybe 3-4L or wort and the rest buy a wyeast.

As for buying their lowest abv beer, wouldn't their different beers use slightly different strains?


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## manticle (16/4/15)

Most of the trappists use a single strain (within each brewery). Some breweries have historically shared some of their yeast with other breweries when needed.


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## manticle (16/4/15)

If you follow one of the threads on building up a starter from a slant, that will likely be as close as you get. Slants are usually made from virgin yeast whereas you have slutty, town bike stuff (if it's that quad yeast you spoke of in another thread) so who knows what genetic drift the surviving yeast cells might be prone to but worth a crack for fun.


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## eMPTy (16/4/15)

That was my thought. Worth a crack. Will do a small amount with the harvested yeast, bought a wyeast pack for the rest.


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