Estimating Cell Count - Home Brew Forums
Home Brew Forums > Home Brewing Beer > Fermentation & Yeast > Estimating Cell Count

Reply
 
Thread Tools
Old 02-02-2013, 01:02 AM   #1
beerluvva
Recipes 
 
Jan 2013
Posts: 94
Liked 4 Times on 3 Posts



I'm pondering washing the yeast from a batch that I'm bottling tonight. I intend to make a starter with it for my next batch. But my question is: with yeast harvested from a given fermentation, and then run through a starter, how do you know with any kind of accuracy how many cells you are working with, and therefore if you're overpitching/underpitching to the next batch ? Or is it more of a try it, and if it works, repeat... type of process ?



 
Reply With Quote
Old 02-02-2013, 01:11 AM   #2
ACbrewer
HBT_LIFETIMESUPPORTER.png
Recipes 
 
Jan 2011
Fredericksburg, VA
Posts: 1,684
Liked 118 Times on 105 Posts


to really know you need some specialized equipment.
A microscope, and there is a special plate to put the yeast sample on, which puts a grid in the view for you, then you put on a measured amount of yeast slury - something like a drop, but it is very specific in size, like a micro liter (.001 ml) - ok, I probably have that size wrong. with it on the grid, you can count the cells. After geting a count (1500) in .001 ml, then you know you have 1500,000 per ml etc etc.

After that I've got now idea how to figure it from a batch of starter by eyeballing it. A brewer at work makes a judgement by the kerousan ... if he gets a high one for that style yeast, he repitches, if it is low, he buys new.



 
Reply With Quote
Old 02-02-2013, 01:16 AM   #3
ResumeMan
HBT_SUPPORTER.png
 
ResumeMan's Avatar
Recipes 
 
Nov 2011
Oakland, CA
Posts: 471
Liked 28 Times on 27 Posts


Well the answer is...you don't know with any decent accuracy, really. But then again, the amount of yeast needed for a batch is also known only to a broad estimation.

The best approach is probably to plug the amount of slurry you have into the MrMalty yeast calculator for slurry, making your best guess as to the parameters like yeast% and such. Then use that number in your starter calc either on MrMalty or YeastCalc.com. And then maybe adjust your starter amounts upward a bit, since it's generally accepted that it's better to overpitch a bit than to underpitch.

But really, without instruments it's a seat-of-the-pants type situation.
__________________
I am not drunk! I am by nature a loud, friendly, clumsy person!

 
Reply With Quote
Old 02-02-2013, 02:08 AM   #4
tagz
Recipes 
 
Jan 2008
Posts: 1,913
Liked 252 Times on 174 Posts


I think I read recently that one of the labs says a standard slurry of 40-60% yeast will have 1.2 billion per ml. Then you can calculate a loss in viability as it gets older. You should check out woodland brewing blog; he has viability numbers. Generally storage is better than the yeast calcs will indicate.

 
Reply With Quote
Reply
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Estimating cell count krahm Fermentation & Yeast 5 06-09-2012 02:07 AM
Is there a cell count database? BVilleggiante Fermentation & Yeast 3 06-04-2012 04:36 PM
Cell Count zrule Fermentation & Yeast 4 04-11-2012 09:56 PM
I know target cell count, but... Saccharomycetaceae Fermentation & Yeast 5 11-09-2011 02:43 PM


Forum Jump