dry yeast cell counts

[wort-h.o.g]

I don’t use dry yeast very much, and am using it for an apple ale this weekend- using s-04.

seems like much variability in consensus of cell count per gram of dry yeast. for my 1.050 apple ale, target pitch is 185BB. 2 packs of s-04 at 6BB (manufacturer count) would require me to pitch 31g or almost 3 packs.

are the  manufacturers estimates solid or should i use higher average cell count per gram?

Kai’s findings:

Dry Yeast - billions of cells per gram:

No one agrees on the number of yeast cells per gram in dry yeast!
    This is made more confusing because each yeast strain has different size cells and clumping tendencies.
    We put in a reasonable default of 10 billion cells per gram of dry yeast.
    Kaiser located a study which reports the following data on dry yeast ranging from 8-18 billion cells per gram:
    Yeast B cells/g
    Safale K-97 14
    Safale S-04 8
    Safbrew T-58 18
    Safbrew S-33 16
    Saflager S-23 10
    Saflager S-189 9
    Adapted from: Van Den Berg, S., & Van Landschoot, A. (2003). Practical use of dried yeasts in the brewing industry. CEREVISIA, 28(3), 25-30 (Table 1).

Mr.Malty says that dry yeast contains 20 billion cells per gram. Unfortunately we could not find a reference to a study that supports that number.
    From the manufacturers:
        Fermentis: > 6B cells/gram for US-05 and S-04.
        Danstar: > 5B cells/gram for Nottingham yeast.
        These numbers sound conservative and do not match with the study referenced above. According to our pitching calculator, with dry yeast, using the mfg’s number of 6B cells/g, to hit a pitch rate of 0.75 (M cells / ml / ° P) for a 5 gallon batch @1.050 would require 3x 11g packs!
    Link to a researcher claiming 20B, but only has an n of 1.
    Most dry yeast packs come in 5g or 11g amounts. With dry yeast, starters are typically not made because dry yeast is relatively cheap - just buy more packs to hit the target pitch rate.

[hopfenundmalz]

Good information. Thanks.

[wort-h.o.g]

@hopfenundmalz

Good information. Thanks.

good but seemingly more difficult to determine correct pitch with so much variability in starting cell count per gram of dry yeast.

[denny]

Did Kai say how big a sample he used?  How many packs of each were evaluated to make sure he wasn’t seeing an anomaly?

[denny]

@denny

Did Kai say how big a sample was used?  How many packs of each were evaluated to make sure they weren’t seeing an anomaly?

[archstanton]

I would go with the manufacturers, they have phd’s in microbiology and do cell counts for a living.
If you do then assume the manufacturers are correct, it will shatter the validity of the “pitching rate” and the liquid starter necessity. Which also just so happens to be what the manufacturers say. HMMMM

[wort-h.o.g]

@denny

@denny

Did Kai say how big a sample was used?  How many packs of each were evaluated to make sure they weren’t seeing an anomaly?

no that’s all the info. mentions manufacturer data likely conservative.

[wort-h.o.g]

@denny

Did Kai say how big a sample he used?  How many packs of each were evaluated to make sure he wasn’t seeing an anomaly?

got a feeling you’ve got experience and opinion on this- what say you good sir?  trying to make sense of the dry yeast world.

[denny]

@wort-h.o.g

@denny

Did Kai say how big a sample he used?  How many packs of each were evaluated to make sure he wasn’t seeing an anomaly?

got a feeling you’ve got experience and opinion on this- what say you good sir?  trying to make sense of the dry yeast world.

Nothing specific, but it just strikes me as strange that yeasts from the same manufacturer would vary so widely.  I dunno, maybe it’s not weird in reality.  But unless we know the sample size, I question how much validity the data has.  I mean, what if they only tested one pack of each?  That seems unlikely, but we just don’t know.

[wort-h.o.g]

@denny

@wort-h.o.g

@denny

Did Kai say how big a sample he used?  How many packs of each were evaluated to make sure he wasn’t seeing an anomaly?

got a feeling you’ve got experience and opinion on this- what say you good sir?  trying to make sense of the dry yeast world.

Nothing specific, but it just strikes me as strange that yeasts from the same manufacturer would vary so widely.  I dunno, maybe it’s not weird in reality.  But unless we know the sample size, I question how much validity the data has.  I mean, what if they only tested one pack of each?  That seems unlikely, but we just don’t know.

precisely- that’s the dilemma. mr. malty generically list every dry yeast at 20bb/gr, and im sure other calcs use some default that varies from the others. seems like 10bb/gr would be reasonable minimum expected, but hen again reason doesn’t always pan out.

[a10t2]

I’ve only done counts on US-05 (and only a few) but it runs 20 billion/gram, give or take.

[wort-h.o.g]

@a10t2

I’ve only done counts on US-05 (and only a few) but it runs 20 billion/gram, give or take.

and manufacturer list 6BB/gr for US-05…go figure.

so perhaps experience can weigh in here. for avg 1.050 ale with target of approx 185-200BB- a.) have you pitched 1 pack with good results or where there signs of under pitching, or b) have you pitched 2 or 3 packs with good results or where there signs of over pitching.

[ynotbrusum]

34/70 pitches fine in 5 gallons of sub 1.050 wort at lager temps, but I rehydrate

[morticaixavier]

@wort-h.o.g

@a10t2

I’ve only done counts on US-05 (and only a few) but it runs 20 billion/gram, give or take.

and manufacturer list 6BB/gr for US-05…go figure.

so perhaps experience can weigh in here. for avg 1.050 ale with target of approx 185-200BB- a.) have you pitched 1 pack with good results or where there signs of under pitching, or b) have you pitched 2 or 3 packs with good results or where there signs of over pitching.

one packet (11 grams) in 1.050 is just fine. I’d even go one packet in 5 gallons of 1.070 and not worry about it.

I suspect the manufacturers estimate low in order to prevent complains. of course they also say 200b cells per packet which, by the way is just about 20b/gram

[wort-h.o.g]

@morticaixavier

@wort-h.o.g

@a10t2

I’ve only done counts on US-05 (and only a few) but it runs 20 billion/gram, give or take.

and manufacturer list 6BB/gr for US-05…go figure.

so perhaps experience can weigh in here. for avg 1.050 ale with target of approx 185-200BB- a.) have you pitched 1 pack with good results or where there signs of under pitching, or b) have you pitched 2 or 3 packs with good results or where there signs of over pitching.

one packet (11 grams) in 1.050 is just fine. I’d even go one packet in 5 gallons of 1.070 and not worry about it.

I suspect the manufacturers estimate low in order to prevent complains. of course they also say 200b cells per packet which, by the way is just about 20b/gram

So your experience is that one packet isn’t under pitching? Just asking because 6b/gr is a long way off from 20b/g

[jonhughey_att.net (HoosierBrew)]

@morticaixavier

one packet (11 grams) in 1.050 is just fine. I’d even go one packet in 5 gallons of 1.070 and not worry about it.

+1. I prefer liquid cultures but have used dry yeast many times for short notice brewing.  When I get up around 1.075-ish I’ll use 2 packets. Up to that point 1 has worked perfectly fine for me.

[wort-h.o.g]

@morticaixavier

one packet (11 grams) in 1.050 is just fine. I’d even go one packet in 5 gallons of 1.070 and not worry about it.

+1. I prefer liquid cultures but have used dry yeast many times for short notice brewing.  When I get up around 1.075-ish I’ll use 2 packets. Up to that point 1 has worked perfectly fine for me.

awesome guys thanks for the info-good timing as in an hour i will be pitching the rehydrated yeast.

[morticaixavier]

@wort-h.o.g

@morticaixavier

@wort-h.o.g

@a10t2

I’ve only done counts on US-05 (and only a few) but it runs 20 billion/gram, give or take.

and manufacturer list 6BB/gr for US-05…go figure.

so perhaps experience can weigh in here. for avg 1.050 ale with target of approx 185-200BB- a.) have you pitched 1 pack with good results or where there signs of under pitching, or b) have you pitched 2 or 3 packs with good results or where there signs of over pitching.

one packet (11 grams) in 1.050 is just fine. I’d even go one packet in 5 gallons of 1.070 and not worry about it.

I suspect the manufacturers estimate low in order to prevent complains. of course they also say 200b cells per packet which, by the way is just about 20b/gram

So your experience is that one packet isn’t under pitching? Just asking because 6b/gr is a long way off from 20b/g

that has been my experience. I have been dinged in competition for too few esters pitching 1 packet of us-05 into 5 gallons of 1.065 IPA

[system]

@denny

Nothing specific, but it just strikes me as strange that yeasts from the same manufacturer would vary so widely.

The cell count per gram delta is due to yeast cell size.

[system]

@wort-h.o.g

So your experience is that one packet isn’t under pitching? Just asking because 6b/gr is a long way off from 20b/g

You are reading the specification incorrectly.  The number listed is the lower bound, not the upper bound or actual cell count.  For those who have studied computer science (comp sci), think of the number as Ω(cell_count_per_gram), not O(cell_count_per_gram) or Ɵ(cell_count_per_gram).  Comp sci types can also think of yeast cell growth as O(2ⁿ).  I know that comparing yeast cell counts to asymptotic growth rates is a weird analogy, but hopefully it helps a few forum readers.