Estimates of rinsed yeast population/Density

Australia & New Zealand Homebrewing Forum

Help Support Australia & New Zealand Homebrewing Forum:

Joined
17/4/22
Messages
157
Reaction score
31
Location
Greater Brisbane
IMG_20220516_163000.jpg


Here is some notingham yeast I havested and I'm trying to work out my pitch rate for my next brew, but I'm unsure on the yeast count.
Some sites say 1 billion cells per ml some 1.5 and one site even says 4 billion if thick and condensed which is it?
Obviously I know this is just a guess and I'm also not factoring viability but thier is so much speculation and opinions on this topic also this would be logarithmic and not linear etc.
 

MHB

Well-Known Member
Joined
1/10/05
Messages
6,794
Reaction score
4,249
Location
Newcastle
Lacking anything like enough information the "Standard" rule of thumb is that 0.5L will give you 15Million cells/mL in 1HL (Hectolitre).
That is for very fresh yeast from the cone of a CCV. The trub would have been dropped once or twice before the yeast for repitching was collected. Meaning pretty clean yeast and in really good condition
Standard assumptions are that yeast kept under water is to be used in a couple of days, under wort (~1.020-30) within a week or two if kept very cold... Call it well looked after.

Applying the standard pitching rate for Ale yeast 0.6-1Million cells/mL/oP
If you are pitching into a 1.050 wort (12.5oP) that was say 25L, and chose to pitch at say 1*10^6 cells/mL
You need
1*10^6 X 25,000 X 12.5 = 312,500,000,000 cells (3.125*10^11) (312.5 Billion)

From the standard 500ml will give you 100L (100,000mL) at 15million/ml.
500mL = 100,000 X 15*10^6 = 1.5*10^11/500 = 3*10^9 cells/mL
As you need 3.125*10^11
3.125*10^11/3*10^9 = 104mL
That’s at the top end of the ale pitching range

Nice in theory, I would be much more inclined to make a starter, I don’t really trust yeast that’s been stored for any length of time both from a hygiene point and yeast population/vitality to.
If you acid washed one of your slabs, then pitched it into a well aerated starter I suspect you would get better and more consistent results.
Mark

PS
Just doing the numbers of the top of my head, if I have made any obvious mistakes someone will point them out, i'm sure.
M
 
Joined
17/4/22
Messages
157
Reaction score
31
Location
Greater Brisbane
Lacking anything like enough information the "Standard" rule of thumb is that 0.5L will give you 15Million cells/mL in 1HL (Hectolitre).
That is for very fresh yeast from the cone of a CCV. The trub would have been dropped once or twice before the yeast for repitching was collected. Meaning pretty clean yeast and in really good condition
Standard assumptions are that yeast kept under water is to be used in a couple of days, under wort (~1.020-30) within a week or two if kept very cold... Call it well looked after.

Applying the standard pitching rate for Ale yeast 0.6-1Million cells/mL/oP
If you are pitching into a 1.050 wort (12.5oP) that was say 25L, and chose to pitch at say 1*10^6 cells/mL
You need
1*10^6 X 25,000 X 12.5 = 312,500,000,000 cells (3.125*10^11) (312.5 Billion)

From the standard 500ml will give you 100L (100,000mL) at 15million/ml.
500mL = 100,000 X 15*10^6 = 1.5*10^11/500 = 3*10^9 cells/mL
As you need 3.125*10^11
3.125*10^11/3*10^9 = 104mL
That’s at the top end of the ale pitching range

Nice in theory, I would be much more inclined to make a starter, I don’t really trust yeast that’s been stored for any length of time both from a hygiene point and yeast population/vitality to.
If you acid washed one of your slabs, then pitched it into a well aerated starter I suspect you would get better and more consistent results.
Mark

PS
Just doing the numbers of the top of my head, if I have made any obvious mistakes someone will point them out, i'm sure.
M
I'm thinking about a starter and your pretty spot on with the pitching rate (according to calc 285billon) but I'm trying to find a ball park estimate for the yeast per ml in solution
 

MHB

Well-Known Member
Joined
1/10/05
Messages
6,794
Reaction score
4,249
Location
Newcastle
From above
"From the standard 500ml will give you 100L (100,000mL) at 15million/ml.
500mL = 100,000 X 15*10^6 = 1.5*10^11/500 = 3*10^9 cells/mL"

Thats 3 Billion c/mL in a fresh ckean well compacted slurry.
How yours measures up is a very open question but its way better to over pitch than to under pitch (within reason).
Mark
 
Last edited:
Joined
17/4/22
Messages
157
Reaction score
31
Location
Greater Brisbane
Fron above
"From the standard 500ml will give you 100L (100,000mL) at 15million/ml.
500mL = 100,000 X 15*10^6 = 1.5*10^11/500 = 3*10^9 cells/mL"

Thats 3 Billion c/mL in a fresh ckean well compacted slurry.
How yours measures up is a very open question but its way better to over pitch than to under pitch (within reason).
Mark
Thanks mark
 

Latest posts

Top