# Dry Yeast Cell Count



## dabre4 (13/9/12)

I am going to do a high gravity brew this weekend (OG = 1.106). I normally use liquid yeast and build up starters according to the calculated viability of the pack by the manufactured date. For this brew I am going to use S05 as I figured it will be easier and cheaper to get the required pitching rates then from liquid yeasts. I have a bit of confusion about the number of "viable" cells there are in a pack of dry yeast. In the past, and going by Mr Malty, I have figured that there are around 20 billion yeast cells per gram of dry yeast, so in a 11.5 g pack around 230 billion cells. However, I found the spec sheet on S05 from the fermentis website, see here. This states that there are 6 x 10^9 (6 billion) cells per gram. This would mean there are only around 69 billion cells in a 11.5 gram pack, that's much less then the supposed 100 billion in a fresh pack of liquid yeast. So what is correct? What fermentis are quoting seems too low, as too my knowledge the 11.5 g packs of dry yeast are meant to have much more yeast then the liquid. Unless of course I am reading this wrong. 

Cheers


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## [email protected] (13/9/12)

I am not sure about exact cell counts. I would think what you end up with would have a lot to do with how you prepare and pitch your dry yeast, also how old the pack is and how it has been stored.

For a beer that big, personally i would be looking at 1.5 to 2g of dry yeast / L rehydrated according to fermentis instructions.


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## MHB (13/9/12)

Personally I would trust the manufacturer, what incentive is there for them to quote a number 2/3 or more lower than is actually in the pack?
Realistically that will be a minimum number for a packet at the end of its shelf life, under recommended storage conditions. From my reading dry yeast will lose about 20% of its viability/year at 20oC and only about 4% at 4oC, so very young very well looked after yeast could be giving a cell count in the order of around 1*10^10 (10*10^9 or 10 Billion) still half of what Jamil says he sees.
If you look at the tech sheets for both Danstar and Mauri (the other two makers of dry yeast widely available in Australia) you will see cell counts compatible with those made by Fermentis.
This is just one of the reasons I view Mr Malty and the Yeast Book with just a touch of caution (well outright scepticism in places)
For a beer that big I would be thinking Active Starter rather than just about the pitch rate
Mark

I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration I will not.........
m


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## dabre4 (13/9/12)

Interesting. I wonder where this perceived 20 billion/g has come from. I've already bought the packs, if I knew they were only 69 billion per pack I would have just got some 1056 and built it up in a starter. Lesson learnt.


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## Wolfy (13/9/12)

MHB said:


> I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration; I will not talk about yeast rehydration I will not.........
> m


Maybe the manufacturer quoted numbers assume you will sprinkle the yeast directly, while MrMalty's calculations assume you will hydrate, then going on JZ/JP's assertion that 1/2 the cells die when sprinkled directly, you end up with the same number of viable cells in both situations. 

But as *MHB *said, there is no reason or logic for the manufacturer to seriously under-estimate the number of yeast cells they provide in a packet, and one would assume they have a good idea of what they put into what they make.


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## felten (13/9/12)

The best way to get an answer dry yeast part of the mr. malty calculator is to contact Jamil and ask him. A lot of people use the calc verbatim, and if they were underpitching by 3/4 I would have thought it would have been brought up by now.

IIRC he measured the cell count himself and confirmed the number with other people who had done measurements as well to arrive at 20 billion per gram.

http://www.mrmalty.com/pitching.php#s3


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## dabre4 (13/9/12)

Cheers. So according to Jamil:

"Recently there have been other numbers mentioned for cells/gram of dry yeast and folks have asked me why I believe there are 20 billion cells. I've actually done cell counts on dry yeast and they're always 20 billion per gram +/- less than a billion. Dr. Clayton Cone has also stated that there are 20 billion per gram, and other folks I trust tell me that 20 billion is correct."

Based in this I will go on assuming they are 20 billion/g. Still, I can't see any sense in the manufacture grossly underestimating the amount if yeast per pack. It must be to cover their arse in the cases where their yeast is mistreated and not re-hydrated correctly. In saying that though Wyeast claim 100 billion and I know for a fact that even fresh packs don't have that many viable cells.


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## hoppy2B (13/9/12)

Yeast nutrition would have to be way more important than pitching rate.


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## manticle (13/9/12)

Please elaborate.


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## hoppy2B (13/9/12)

If you're going for esters for the purpose of creating a brew worth aging then low pitch rate is actually meant to be better. The actual type of esters you are producing is also dependent on the quality of the nutrient available.
I'd be selecting something other than us05.


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## hoppy2B (13/9/12)

Or in lay terms, you can't make good beer from shit wort using good yeast. :lol:


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## MHB (13/9/12)

Beginning to wonder if I am the only one who sees something wrong with the guy who co-authored a book with a manufacturer of liquid yeast being totally at odds with the three big manufacturers (all much bigger than Whitelabs) and their paid professional yeast experts.
Considering the scant mention of dry yeast given in Yeast: The Practical Guide to Beer Fermentation (Brewing Elements) you would be left in no doubt as to the bias of the authors.
And yet we are asked to take Jamils word for how many yeasts are in a packet and the best way to handle that yeast.
Like I said isnt anyone just a little cynical arent there any faint tinkling of alarm bells in the distance?
The idea that you must rehydrate yeast reference Chris White/Jamil
That half your yeast will die if you dont same/same
That you get 3-4 times as many yeast cells as the maker claims think about it.
I guess if you use dry yeast and you follow Mr Maltys advice and dont get the results you wanted you should have brought a liquid culture in the first place dont worry you will know better next time seriously?

I both use and sell both dry and liquid cultures, both have their place but I never bother with Mr Malty, I really think he cant count and I am quite capable of working out from the manufacturers cell counts how much yeast I need in a brew.
Mark


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## Wolfy (14/9/12)

@*Doog* we don't really get 'fresh' packs of yeast here, we only get those that are shipped internationally that are often weeks or months past being 'fresh'.

@*MHB*, I think dried yeast gets mentioned once or twice in the 'Yeast' book, one is in a small little box at the bottom of the page - it's hard not to notice the bias. 

However, every yeast information .pdf file I have downloaded from Danstar/Fermentis (I've never had need to visit/review Mauri's website/documentation) outlines detailed rehydration procedures and either cell count and/or pitching quantity information - which one would presume should be trusted.


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## MHB (14/9/12)

I am trying to avoid getting into another discussion about rehydration but will repeat what I have said many times in the past namely Follow the manufacturers instructions, exactly.
The advice offered by many here and in other media very rarely goes anywhere near being complete and is often at odds with what the maker recommends. Please note that Fermentis dont just recommend rehydration, equal weight is given to just sprinkling into the wort (with recommended temperatures), they offer two equally effective alternatives.

I did a bit more reading last night, from what I can gather if you want a real viable yeast count you dilute a sample plate it out and count the colonies, this is I suspect how the manufacturers reach the number they state. It is pretty well known that at least half of the cells die during freeze drying, they probably rehydrate pretty well and look just like live cells under a microscope they are still dead.
Put that with Jamils cell count and the back of an envelope numbers posted above, its quite possible that if you rehydrate some dry yeast and do a quick count you are seeing 20Billion cells, just not 20Billion live ones.
Mark


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## hoppy2B (14/9/12)

I wouldn't be overly fanatical about following the instructions from yeast manufacturers. Its in their interest to tell you to chuck out a packet of yeast if more than 7 days have elapsed since you opened it. That way you go out and buy more yeast. The same thing with pitching rates etc. Not saying that you shouldn't pitch a good amount of yeast, just that all their instructions seem to be aimed at getting you to use as much of their yeast as possible. :angry:


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## Yob (14/9/12)

hoppy2B said:


> Yeast nutrition would have to be way more important than pitching rate.






hoppy2B said:


> Not saying that you shouldn't pitch a good amount of yeast



ummm. Yeah you did





Nice one Roxo


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## hoppy2B (14/9/12)

I'd rather pitch a smaller than average amount of yeast into a great wort than pitch a 'scientifically' calculated amount of yeast into a shit wort. :lol:


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## MHB (14/9/12)

I think the point of brewing is to pitch the right amount of yeast into the best wort I can make!
When did making crap wort come into the discussion, just looking up this page Im seeing something like 5 totally irrelevant OT posts by Hoppy2B intruding into an otherwise interesting discussion.
Mark


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## hoppy2B (14/9/12)

You're entitled to your opinion MHB..... I don't agree with it. :lol:


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## manticle (14/9/12)

Your opinion, based on something tangible like your experience or research or a combination of both, clearly outlined and explained would be very welcome.

The problem is that you seem to make statements, phrased as being factual, that have little _obvious_ basis in either of those.

If you have some justification for statements such as 



> Yeast nutrition would have to be way more important than pitching rate.



OR



> If you're going for esters for the purpose of creating a brew worth aging then low pitch rate is actually meant to be better. The actual type of esters you are producing is also dependent on the quality of the nutrient available.



then let people know. Who says it's meant to be better? Why is it meant to be better? I've heard of low pitch creating esters but not about a blanket 'better for aging beers'. I age a few beers - I'd like to know who said so and why.

Not saying you're wrong - I just have no reason to think you're right and you're not giving me any.

This is a place where people (most people hopefully, myself included) learn new things. I can speak only for myself but I see people learning best from those who seem to know what they're talking about and are happy to share their knowledge and resources.


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## dabre4 (14/9/12)

> Yeast nutrition would have to be way more important than pitching rate.



Don't really agree with that, I will be adding yeast nutrient as it is an important addition with high gravity brews, but I'd say that pitching an ample amount of yeast is more important. 

I know when counting cells with a hemocytometer (I'm assuming Jamil's method for counting) you can use methylene blue to "stain" dead or weak cells. Whether he did this or not during cell counts I can't say. If he was on White Labs side and was trying to damage the name of dry yeast, why the hell would he be saying that dry yeast packs have more viable cells then liquid, I would have thought he'd point at that they have less if that was the case. 

I found this article which backs up what Jamil is claiming. This seems to suggest that dry yeast are very fragile and that during the re-hydrating stage (with the sprinkle method or re-hydrating separately) the cell walls are very weak, and that it takes up to 30 min for the yeast to build up their walls using the inbuilt glycogen and trehalose provided by the manufacture before they are strong enough to perform fermentation. As others have mentioned perhaps the manufacturer assumes that during this stage around 60 % of the cells will not be viable and only 40% will be good for fermentation. This bring the 20billion cells/g back into range the manufactures claim of 6 billion cell/g. 

I get the feeling their is a bit of truth to both sides. I think Jamil and others who conduct cells count are in fact counting cells that won't be viable. I also think the manufacture assumes that under worst case conditions after re-hydration their will be at least 6 billion/g. 

Another point is that the S05 packs claim their is enough yeast to ferment 20 - 30 liters. Let assume the best case scenario, a 20L low gravity brew with an OG of 1.035, the recommended pitching rate is around 130 billion. Let say more realistically a 24 L batch with an OG of 1.052, the recommended pitching rate is around 230 billion. A worst case scenario (within reason), a 30 L batch with an OG 1.060, the recommended pitching rate is around 330 billion. How can they claim their are only 69 billion viable cells in a pack (6 billion/g x 11.5g) and then claim you can pitch it in 20 - 30 L? Now if we assume their are 230 billion in a pack (20 billion/g x 11.5g), as Jamil and others claim, this seems to match the 20 - 30 L recommended volume by the dry yeast manufacturer. I would like to trust the manufacturer, but what they are claiming, to me, doesn't quite match up.


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## Nick JD (14/9/12)

Doog said:


> Don't really agree with that, I will be adding yeast nutrient as it is an important addition with high gravity brews, but I'd say that pitching an ample amount of yeast is more important.
> 
> I know when counting cells with a hemocytometer (I'm assuming Jamil's method for counting) you can use methylene blue to "stain" dead or weak cells. Whether he did this or not during cell counts I can't say. If he was on White Labs side and was trying to damage the name of dry yeast, why the hell would he be saying that dry yeast packs have more viable cells then liquid, I would have thought he'd point at that they have less if that was the case.
> 
> ...



Great post.


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## sama (14/9/12)

as a guide mr malty and those fellas pitching rates seem to work,dosent it? well does for me..great info provided tho.


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## bigfridge (15/9/12)

Doog said:


> I found this article which backs up what Jamil is claiming. This seems to suggest that dry yeast are very fragile and that during the re-hydrating stage (with the sprinkle method or re-hydrating separately) the cell walls are very weak, and that it takes up to 30 min for the yeast to build up their walls using the inbuilt glycogen and trehalose provided by the manufacture before they are strong enough to perform fermentation.



I had the pleaseure of chatting about yeast with Dr Cone in the HBD Fortnight of Yeast (was it really way back in 2003 !) and the information about re-hydration was first paosted as part of this serries of questions.

There is no doubt that this procedure give optimal results with the Danstar yeasts. But as a followup (it may have been Wes Smith who posted it) this does not apply to all yeast manuafturers equally. Fermentis use a different manuafcturing process which is why they recommend to 

"Re-hydrate the dry yeast into yeast cream in a stirred vessel prior to pitching. Sprinkle the dry yeast in 10 times its own weight of sterile water or wort at 23C 3C. Once the expected weight of dry yeast is reconstituted into cream by this method (this takes about 15 to 30 minutes), maintain a gentle stirring for another 30 minutes. Then pitch the resultant cream into the fermentation vessel.
Alternatively, pitch dry yeast directly in the fermentation vessel providing the temperature of the wort is above 20C. Progressively sprinkle the dry yeast into the wort ensuring the yeast covers all the surface of wort available in order to avoid clumps. Leave for 30 minutes and then mix the wort e.g. using aeration."

As MHB says follow the manufacturers directions - contrary to popular beleif they would much rather that you continue to buy yeast due to getting good results.



Doog said:


> I know when counting cells with a hemocytometer (I'm assuming Jamil's method for counting) you can use methylene blue to "stain" dead or weak cells.
> 
> ...
> 
> I get the feeling their is a bit of truth to both sides. I think Jamil and others who conduct cells count are in fact counting cells that won't be viable. I also think the manufacture assumes that under worst case conditions after re-hydration their will be at least 6 billion/g.



I don't have a reference handy, but I believe that methylene blue has been discredited as it also stains the glycogen in healthy cell walls. I can probably look up some stuff later if ya'all ask nicely.

HTH,

Dave


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## dabre4 (15/9/12)

Cheers Dave.

I think your right about methelyne blue, I've also read something about it only being effective for finding up to 10 to 20% if unviable cells, probably related to what your saying.


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## felten (15/9/12)

MHB said:


> Beginning to wonder if I am the only one who sees something wrong with the guy who co-authored a book with a manufacturer of liquid yeast being totally at odds with the three big manufacturers (all much bigger than Whitelabs) and their paid professional yeast experts.
> Considering the scant mention of dry yeast given in Yeast: The Practical Guide to Beer Fermentation (Brewing Elements) you would be left in no doubt as to the bias of the authors.
> And yet we are asked to take Jamils word for how many yeasts are in a packet and the best way to handle that yeast.
> Like I said isn’t anyone just a little cynical aren’t there any faint tinkling of alarm bells in the distance?
> ...


What a crock... You sound a little too much like NickJD with the conspiracy BS. 

Dr. Clayton Cone, who I believe is the head of the lallemand yeast lab, has made statements about the cell count per gram, and pitching death rate that agree with what Jamil/Chris White are saying.

ref; http://koehlerbeer.com/2008/06/07/rehydrat...r-clayton-cone/



Dr. Cone said:


> Each gram of Active Dry Yeast contains about 20 billion live yeast cells. If you slightly damage the cells, they have a remarkable ability to recover in the rich wort. If you kill 60% of the cell you still have 8 billion cells per gram that can go on to do the job at a slower rate.



ed: no offense intended Nick, or Mark


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## Nick JD (15/9/12)

felten said:


> What a crock... You sound a little too much like NickJD with the conspiracy BS.



Comparing Mark's comments to mine is probably the biggest insult you could make to him, and the biggest compliment you could make to me. I'd think you were even cooler if you weren't from the CIA and your name wasn't a toiletpaper brand. One should never trust toiletpaper - I'm pretty sure that's how they get the probe in all of us.


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## Batz (15/9/12)

It been an interesting thread with some good information being posted.

Thanks to the posters who have contributed. Lets let everyone have their say without getting personal with shit slinging hey? Believe me I get my share of this these days and I believe it's cowardly.


Now me?

I use dry yeast on occasions and I sprinkle it on the wort, works for every time for me. How many yeast cells are in there, really I don't give a Tinkers Cuss as long as it works.

I do like to learn the science behind this stuff though.

Now be nice possums

Batz


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## MHB (16/9/12)

It has nothing to do with conspiracy theory, I was simply trying to highlight the circular nature of the discussion; the point that a book that purports to be the final word on yeast for home brewers basically ignores dry yeast isnt acceptable.
I suspect that more than 85%+ of home brew made is produced with dry yeast; I would have had a little more respect for Yeast if they had put in a chapter on dry yeast, even if it was a chapter on why they hate it. The expression to dam with faint praise comes to mind.

The biggest problem I have is that people are sighting Mr Malty/Jamil/The Yeast Book as the reference for almost all discussion regarding rehydrating, pitching, making starters, harvesting... most anything related to yeast (both wet and dry); yet the calculations that Mr Malty bases his work on are at best very suspect, I cant find or think of any reason why all the Dry yeast manufacturers would site Viable Cell Counts 1/3-1/4 of what Jamil reports, nor can I understand why because Jamil says it, it carries more weight than the manufacturer (sorry but that really is nonsensical).
The same type of discussion about how much dry yeast to use, when Fermentis say a packet of (e.g. US-05) is sufficient for 20-25L of wort, people disagree because Jamil says its not enough... the same guy who gives the subject of dry yeast scant attention in his book - I think you can see why I find the whole discussion somewhat bemusing.

Personally any respect I had for Jamil (and I believe he has done a lot of good work) and Chris White (again a maker of fine products that work well) has been largely eroded by the yeast book and things like demonstrating that half the cells are killed by sprinkling into a wort, when we can be fairly sure half of them were dead in the packet ok being generous, put it down to the American view that Hype is the only way to sell your message.
Personally I would like a simple clear explanation of why one choose wet or dry yeast, the relative merits of each, even a bald statement that the author has a personal preference to the treatment dry yeast has been given.

Like I said its not a conspiracy theory, a bit of indignation, a touch of disappointment and not a little contempt.
Im working my way through The Yeast in the Brewery; hard work and very challenging but a thoroughly professional approach to the subject, it just looks at what breweries do, why and the best way to get the results we are aiming for.
Mark


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## Wolfy (16/9/12)

MHB said:


> Im working my way through The Yeast in the Brewery; hard work and very challenging but a thoroughly professional approach to the subject, it just looks at what breweries do, why and the best way to get the results we are aiming for.


Looks interesting ... and expensive.


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## MHB (16/9/12)

And one of those books that makes me regret not doing a lot more study when I had the chance, how does it go youth is wasted on the young.

This thread has sent me off doing a lot of other reading as many of the better threads here do, I dont want anyone to think I have anything but the highest regard for the work of Dr Cone, he is one of the world experts on yeast, there was one discussion on another forum that I thought summed it up pretty well; basically that yeast experts are very good at telling you about yeast health which is their only concern, which is a very different subject to brewing with yeast, for that you need to talk to brewers.
Mark


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