Underpitched Wyeast 1272 - How to determine cell count?

[foodplusbeer]

I brewed 5.25 gallons Amarillo/Citra IPA with an OG of 1.062. A week after fermenting it tastes and smells very belgiany (lots of fruity esters and phenols). I used Wyeast 1272 and it doesn’t taste bad per se, it's just not what it should be (I've brewed with this yeast before and love it). I guess I now have a Belgian IPA on my hands. The question is, to what can I attribute this flavor from? I'm guessing pitching rates, but I'd like some help with the calculations... Here's the information I've accumulated.

Used 50ml Wyeast 1272 slurry harvested on 1/29/2012, 10% viability according to Mr. Malty

Used 2C water, .5C LDME (about 2 oz) to make starter (Fermented at 68 degrees, yeast was very active, good krausen)

After 24 hours, pitched starter into 75 degree wort, put ale pail in 65 degree basement

Mr Malty Says I needed 226 Billion Cells (1038ml slurry)​

Given this information, how can I calculate how much yeast I actually pitched? If 1038ml is 226 Billion cells then my sample had 10.9 billion cells [EDIT!] (Viable Cells) [/EDIT]. How many viable cells would I have had after making the starter?

Question 2 - If I had harvested the yeast from this batch, would this yeast continue to put out the Belgian characteristics if I used a proper pitching rate, or are the esters solely a biproduct of underpitching?

 

[duboman]

You don't state the fermentation temperature but that could be the cause of your issues if you fermented at the higher end of tolerance.

It is virtually impossible to count cells unless you have a microscope and a lot of time. There is a way to determine the approximate count by calculating the weight of the yeast based upon the weight of a known quantity of packaged yeast like a White Labs vial.

In other words if you have the know quantity in a new vial and can weigh it then you can approximate a similar sample of your own yeast and get an approximate count from that. This is actually discussed in the book "Yeast" by Chris White and Jamil and is the general way it's done.

 

[duboman]

I wanted to add/edit my last comment: If you take a new vial of White labs yeast you know that there are approximately 1B cells in there. If you take the vial and shake everything up into suspension you can then measure the amount of slurry in ml and this will give you an idea of how many cells there are per ml.

According to White labs, before shaking into suspension there are approximately 1B cells per 14ml. The vial volume is 46ml and they are filled to 35ml so in 35ml of slurry there are 1B cells which means there is 21ml of actual liquid.

Kinda confusing, hope this helps you figure this out or an idea of how.

 

[foodplusbeer]

Thanks for the input duboman, I get what you're saying with the weight, but is there anyway to approximate how many cells I would have had after making the starter? Assuming I started with 1.9 Billion viable cells and created a starter with 2oz dme and 2 cups water.

To answer your question, I'm not sure what the fermentation temperature was inside the bucket. I just know that I pitched at 75, and the bucket was in a room at 65. Temperature range for Wyeast 1272 is 60-72.

 

[LLBeanJ]

Try yeastcalc.com. I think you'll find what you're looking for there.

 

[dstar26t]

If you use the default slurry concentration on the pitching rate calculator, there are at most 110 Billion cells in 50 mL of slurry that is 100% viable. 10% is 11 Billion. Putting that 11B into a 473 mL (2 cup) starter will get you an innoculation rate of 23 million cells/mL which should get you 1.9 doublings or 32 Billion cells. That is a fraction of what you needed, no wonder it threw off undesirable esters. Do not re-use the yeast from this batch, it was seriously stressed from that pitching rate.

Nate

 

[foodplusbeer]

Wasn't planning on reusing it, was just curious about the properties of lots of yeast after lots of stress/reproductions.

YeastCalc.com is awesome, and gets me a similar result as DSTAR26T. However it shows viability as 21% and 1.61 doublings to get 60 Billion cells at finish.

So I pitched somewhere between 12% and 25% of what I should have. Still hoping it turns out to be a decent Belgian India Pale Ale! I am going to save my dry hops for another brew though. No need to waste those too...

Thanks for the help!

 

[Gregscsu]

My math puts you around 50 billion pitched into the fermenter

 

[beenjammin]

it seems like using a slurry with only 10% viability wouldn't be worth it. is it generally ok to use a slurry in such a state, assuming you do the steps to rinse the yeast and grow them the proper rates?

 

[dstar26t]

Wasn't planning on reusing it, was just curious about the properties of lots of yeast after lots of stress/reproductions.

YeastCalc.com is awesome, and gets me a similar result as DSTAR26T. However it shows viability as 21% and 1.61 doublings to get 60 Billion cells at finish.

So I pitched somewhere between 12% and 25% of what I should have. Still hoping it turns out to be a decent Belgian India Pale Ale! I am going to save my dry hops for another brew though. No need to waste those too...

Thanks for the help!

My numbers were for a simple starter, no stir plate. Stir plate would get you double the growth, so 53 Billion cells.

Pitching yeast that's sat around for that long is not a good habit to get into. If you have to use it, you need to feed it fresh wort every few weeks. All that handling means a higher risk of contamination so better to start with a new pitch.

 

[foodplusbeer]

To follow up on this, the beer came out great! It scored a 38 at a local competition. The final result did have a very fruity taste but there was nothing unusual about it. Wyeast 1272 tends to end up being fruitier, and I also dry hopped with 2 oz each of amarillo and citra, so no suprise there. I guess it was just green beer. I'll post the recipe soon.