Yeast starter, how many cells do I have?

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willyroyale

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I had a packet of white labs Bavarian weizen wlp-351. It was past the the stated use by date by a month so I thought I'd follow the advice here and elsewhere about making a starter and harvesting, nothing to lose really (except some DME and time).

The packet contained 40g of product (I assume some wort/liquid from the manuf packaging process.

Step 1- pitch to a 500ml wort ~1.040, shaking the flask occasionally for 24-36hrs, popped it in the fridge,

After about a week (I was away from home) I then decanted off practically all the clear liquid. The slurry was rather solid, and weighed approx 54g.

Second step- pitched into 800ml wort didn't account for boil off and hydrometer) ~1.035. Still shaking it. Awaiting results.

I've used calculators on brewers friend and brulosophy which have guided me but my questions are: can I assume that the increase in mass is a sign of success? Would this be an expected increase in weight for a Very low viability yeast? I assume all the solid matter is not yeast?

I brew small batches of 10l though plan on using this (and another low viability packet of white lbs San Diego) in different high OG worts.

incidentally I'm building a stir plate to help in future.

Apologies if my assumption wrong/questions foolish. Trying to understand a complex issue. I tried counting the cells but lost count after 3,078,385 :lol:

Cheers.
 
DME also has a small amount of solids that settle to the bottom, so some of the mass probably comes from it. A good way to know that everything is fine is to taste some of the decanted liquid.
 
I had a packet of white labs Bavarian weizen wlp-351. It was past the the stated use by date by a month so I thought I'd follow the advice here and elsewhere about making a starter and harvesting, nothing to lose really (except some DME and time).

The packet contained 40g of product (I assume some wort/liquid from the manuf packaging process.

Step 1- pitch to a 500ml wort ~1.040, shaking the flask occasionally for 24-36hrs, popped it in the fridge,

After about a week (I was away from home) I then decanted off practically all the clear liquid. The slurry was rather solid, and weighed approx 54g.

Second step- pitched into 800ml wort didn't account for boil off and hydrometer) ~1.035. Still shaking it. Awaiting results.

I've used calculators on brewers friend and brulosophy which have guided me but my questions are: can I assume that the increase in mass is a sign of success? Would this be an expected increase in weight for a Very low viability yeast? I assume all the solid matter is not yeast?

I brew small batches of 10l though plan on using this (and another low viability packet of white lbs San Diego) in different high OG worts.

incidentally I'm building a stir plate to help in future.

Apologies if my assumption wrong/questions foolish. Trying to understand a complex issue. I tried counting the cells but lost count after 3,078,385 :lol:

Cheers.

Hi, if your cells are low viability that is what you will get,,, a slow grinding ferment, regarding the fallout, yes you will get a small amount dropped out from DME but for my pennies worth would suggest that that is most of your yeast cells dead and dropped out. How did the trial jar go, did it ferment proper (vigorous) in the end, if that's the case I would use them, if not you wont be able to recover a good ferment. If you want to get really carried away the way to check viability would be to use something like Fluorescent Stain (I have never used them) but I guess that would be too expensive for us home brewers.
Regards
 
You're probably good. Hard to say exactly how many cell you'll have unless you can estimate starting numbers. I use the spreadsheet version of the site linked below as I have started over-building my starters by 100 billion cells and keeping that for the next batch, which I'll also over build by the same amount.

The guys at basic brewing radio have resurrected yeast that was something like 3 years out of date by stepping it up in starters from 250mls.

Good luck.

http://www.brewunited.com/yeast_calculator.php
 
thanks for the advice.

The trouble I have is what assumptions to make when over - growing/ stepping up a yeast starter.

Brewersfriend and other calculators make assumptions that can be adjusted. However, when I read that I should pitch 1l of yeast starter that means nothing unless I know the approx cell count in that 1l.

I plan to step this 4 times, then split off 75/25 for pitching and storing then try out on a batch.

The exercise for me isnt so much of saving the expense of this white labs sachet, more a learning experience of over-growing yeast starters and having a selection in the fridge Fir future use.

Cheers.
 
The spresheet I linked should help, the pack of yeast has at least 100 billion cells when packaged which is you initial cell count (first entry in the 2nd row). Then as you have white labs yeast the manufacture date is 4 months before the use by date on the packet (according to the help button). That will let the sheet work out your viable cell count.

I just saw that you said the pack was a month past best before date, so I just did an estimate based on 5 month old yeast and got 32 billion cells initially. I've run the numbers you stated above and after the 2nd starter (800ml at 1.035) you should have around 147 billion cells.

Personally I'd now pitch that into 1.5 L of starter wort and you'll get around 240 billion cells assuming manual shaking and a 1.035 wort. If you keep 600 mls then that should have around 100 billion cells for rebuilding the next batch.

I've just built a stir plate as it makes like so much easier, if your yeast gets old and you're shaking manually it's always gonna take 2 starters or more.

Good luck, hope this helps.
 

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