slurry as a new ingredient

[KernelCrush]

Trying to figure the best way to add a yeast slurry as a new ingredient. I must be doing something wrong or failing to account for something.   I added the ingredient as a Culture, changed cells per pack to 2.4B so my recipe would read in ml of slurry.  I go to the Yeast Starter Tool and enter the data and it gives me the slurry needed in liters.  Then I go to the Starter tab and enter that value in ml and it calculates almost 20% cells more than I need according to the Yeast Starter Tool.  All  my dates are correct. 

[drb1215]

Just a thought...Is the Original Gravity in the Yeast Starter Tool the same as the recipe you are building?

-Dan

[KernelCrush]

Yes it is.  Thanks

[KernelCrush]

attached is what i am seeing.   The viability is calculating differently. but that doesnt appear to be the difference between 432 ml shown in the starter tab and 520 ml shown in the starter tool 

[drb1215]

I think I have figured out where the difference is coming from...It's the brew house (total) efficiency that is throwing off the number.  Playing around with it a bit, it looks like the Yeast Starter Tool will give you a results based on approx. 70% BHE.  If you set your BHE (total) to 70% in your recipe the numbers will line up.

-Dan

[KernelCrush]

Thanks for looking at it.  Mine was set at 72%.  I changed it to 70%  and it dropped the ml to 420 from 432 in the tab.  tool is still at 520.

[drb1215]

It looks like numbers calculated for a recipe take your brewing setup into account, where the tool does not know about it.  Also, did you notice that your yeast viability in your top 2 screen shots don't match?

-Dan

[KernelCrush]

Yes I did.  i adjusted the viability to match and it dropped the tool number down to 510 ml.

[KernelCrush]

Interesting to note that Mister Malty splits the difference at 471

[KernelCrush]

The starter tab within the recipe does not factor in the non yeast slurry % while the starter tool does factor it in.  If you zero out this % in Yeast Starter Options the numbers match.  Still gonna go with Mr Malty.

[Pirate Point Brewer]

Being a simple guy, I used Mr. Malty to determine the approximate "Billions of cells" per ounce of slurry based on the typical thickness of the slurry. I use an average value of 60.5 billion cells per ounce. In my ingredients file, I set up "1 Packet" of slurry as follows,

<Name> = "Nottingham - slurry 60.25 Billion/oz"        <Cells per pack> = "60.5"      <Package date> = "Date of slurry harvest"

When designing a recipe I add "1 pack" of my slurry to the recipe. Looking at the starter tab I can see that a brew may need say 336.9 billion cells. Just below this I can see the aged value of viable cells per pack (or ounce) is 59.3 billion/oz. Then I can either use a calculator to divided 336.9/53.9=6.25 oz, or just look down the Starter tab to "Yeast packs to use if No Starter" in this case it indicates 6.

Since after much reading, I subscribe to the "More yeast makes better beer than Less yeast" theory, I pitch whatever is larger and easy to measure. Because I store my harvested slurries in canning jars, 8 oz is an easy measure. So I pitch at lest 8 ozs from the jar.

This method is not as mathematically precise as many described but I'm not convinced it has to be.  It has been very reliable and easy for me to implement and given over 130 successful brews to date.

[KernelCrush]

Thanks for making me take a fresh look at this (and making my head hurt more than it already does this Jan 1).  I blindly plugged in 2.4B cells/ml, but I now see  that that figure doesn't include the 15% non yeast percentage, which adjusts this number down to 2.04B cells/ml.  This 2.04 figure makes it all work like you did only in ml.  Beersmith only gives us one decimal place so it rounds to 2.0, but who's counting? 

Not arguing with your success rate at all, but when you set up your slurry ingredient and are inserting the viability date do you use the actual date harvested?  I have always used the floc date assuming that's when viability starts to decline.  This alters the count pretty dramatically with just 1 week between the 2 dates.

[Pirate Point Brewer]

Sorry for your headache!!  That's what you get for drinking someone else's!!   

As I said, I'm a simple guy so I don't try to make things more complicated than necessary. My brews rarely (never ) stay in the primary more than two weeks.
Therefor the difference between floc date vs harvest date is a few days ... maybe a week. I don't think this time difference is significant. I use harvest date as I believe viability starts decreasing most significantly once the yeast is uncovered from the beer.

The real headache here is that the rate at which the viability declines is significantly variable based on brewer technique, consistency of process, method of storage,  and etc. So I don't pretend to predict any success beyond my own.  I'm a bit of a stickler with myself on consistent processes and techniques. That way I do the same things wrong the same way every time. This gets baked into my overall process and somewhere in that I compensate for those wrong things  and get beer!

The real concept of my reply was to show a simple way to allow BS to do the heavy number lifting brew to brew. Then just accept the answer as a guideline. Without a lab the numbers are all fiction anyway, just like IBU. If you are consistent with your processes and techniques they will guide you toward making your beer the way you want it!

Happy New Year All!

Preston