Yeast harvesting tweak - Any issues?

[DJ_L3ThAL]

Hey guys/gals,

For the last year I've been blindly building my starters ~100 billion cells larger than my required pitch amount and storing that 100 billion cells for re-use. I think it may have been carniebrew who I stole that tip from (sorry can't find the original post).

It has been working great so far with no noticeable ill effect to me (my current WLP001 is on it's 3rd generation), but I was thinking about it and wondering if I was subtly putting some sort of bias/pressure on the yeast? The yeast I am re-using is only grown in a starter environment, which for me is room temperature (fluctuates 15-20C at the moment for example). From my basic yeast knowledge the yeast is still going through the growth phase fully and then settling out in the fridge back to dormant stage before harvesting (I try to allow the extra 12 hours for them to build glycogen reserves up).

So my question is, is there anything I am overlooking or anything I may be causing the yeast to do more or less of through the generations of being grown in just a starter environment? If not, this really is a convenient way for me and no faffing about rinsing slurry! :beer:

 

[Yob]

keep on keeping on

 

[JDW81]

From my reading/research you should be fine up to a point. The issue that eventually arises with reusing yeast (in a HB setting at least) is you are subtly selecting a dominant strain. From my rinsing/reusing experience the yeast reaches it's peak around 3rd generation and starts to drop off by about the 5th (I think Jamil from the BN also has had similar experiences, and speaks about it in one of his shows).

It has nothing to do with sanitation or temperature, it is simply a fact of evolution that one of those yeast lineages will thrive in that environment and start to change the flavour and fermentation profile that may be different from the culture that left the lab.

Other than that, your method looks sound.

Carry on.

JD

 

[Rocker1986]

I've also been using this method over the last few months and loving the simplicity of it. The only difference in my process is that I harvest it before I put it in the fridge to crash... does this make any real difference to it?

 

[DJ_L3ThAL]

Well you'd be harvesting more starter beer with the slurry, so per unit volume of your containet you'd get less yeast.

E.g. i use 50mL vials, typically one of these filled with settled, decanted yeast slurry gets 75% yeast solids when it fully settles out over time and is also around the 100 billion cells. With your method Id say it would settle out to being closer to 5-10% yeast solids, so like for like you would only have 10 billion cells using my vials. Not really a negative if you are using larger containers and harvesting a proportioned amount.

 

[Rocker1986]

Ahh yep, that makes sense. I'm using quart sized Mason jars to harvest after re-mixing the yeast into the 'beer'. I'd imagine the overbuild size of the starter isn't much different though, it's just that I harvest into the jar and let it settle in there, as opposed to settling it in the flask and then harvesting. I first read about this method on the Brulosophy site.

In any case, it has been working well so far and I am rather enjoying the fact that I don't have to faff about rinsing/washing it.

 

[Wilko76]

I've just started using this method as well. I thought it would be quicker and easier than rinsing yeast.
How are you guys estimating the cell count of your settled yeast slurry. I've just been using 3 billion cells per ml as a guide. But I've roughly calculated out over the last few starters that it could be as high as 4.5.
I've been using around 60 - 70 ml of settled yeast for a batch that requires 200 billion cells. Where 50ml should be enough. I only have it sitting in the fridge for a few days up to a week before I use it.
What do you guys estimate your cell count to be from settled yeast harvested from a starter? Or how much slurry do you use?
Cheers

 

[Yob]

use the My Malty slider bars on thick slurry...

 

[Wilko76]

Ok thanks Yob. So you use an estimate of 4.5. Sounds good to me. If harvesting from a starter would you set the non yeast percentage to zero?

 

[mofox1]

For the last year I've been blindly building my starters ~100 billion cells larger than my required pitch amount and storing that 100 billion cells for re-use.

<snip>

So my question is, is there anything I am overlooking or anything I may be causing the yeast to do more or less of through the generations of being grown in just a starter environment? If not, this really is a convenient way for me and no faffing about rinsing slurry!

I would have thought a starter environment is better for yeast health than a full ferment... higher temps, less stress due to lower alc concentration and quicker turn around getting healthy "young" yeast back into the fridge/freezer.

I usually follow a similar path myself, although mostly I either re-build the starter back up after pitching most of it, or the starter is specifically just for filling vials.

The only thing I've noticed is the well "washed" yeast looks at lot nicer. Usually a lot whiter, and obviously the liquid is mostly water with very little spent beer in it. My made-from-starter vials always look a bit cloudy and yellow/orange from the DME.

Just recently been wondering if I should "wash" by starters prior to storing them in vials. I've got a 2L starter of WLP023 that has just finished fermenting out, so I'll probably try it with this one and see how it goes...

 

[Rocker1986]

Hi Wilko,

Admittedly I do take a bit of a stab in the dark with this - however, what I normally do is put all my yeast starter size (inclusive of the overbuild), original cell count, production date etc. information into the Yeastcalc calculator, work out the percentage of it that my 800mL in the jar will be, and then multiply the total cell count prediction by that percentage to get my approx. cell count in the jar.

e.g. if I make a 4 litre starter for a lager yeast, steal 800mL of it then that's 20%. If it calculates that I get 640 billion cells in the 4 litres, then I end up with an estimate of about 128 billion cells in my harvested jar. I then date it and stick it in the fridge. Next time around I make another 4 litre starter, inputting all the info into the calculator, decant most of the jar then pitch all the yeast, reharvest etc. I don't know how precise it is but it's been working well for me so far.

 

[Wilko76]

Ok, that sounds easy enough. I was cold crashing, then decanting, so I was just trying to measure the settled yeast. I reckon 60 to 70 ml should be plenty for an ale.
Cheers

 

[Rocker1986]

It may be obvious from my post but I do harvest the portion of the starter while it's all mixed up on the stir plate, just to clarify that.

I tried the measuring the settled yeast method originally but I found it to be wildly inaccurate because it was bloody hard to work out how many mL I actually had in the bottom of the jar. It depends on the storage vessel of course, but I find the way I documented above to be much easier when working with Mason jars.

 

[Yob]

Put a bit of white contact on your jars, Mark and measure in 50ml increments.. That'll get you close enough to judge by eye