I found this today. I plugged in my recent brew and found I underpitched by 7.93 grams. Oh well, the wort seems to like it.
http://www.lallemandbrewing.com/brewers-corner/brewing-tools/
Something doesn’t seem right. Five gallons of OG 1.042 beer using Nottingham requires 18.93 grams of yeast. Yeast cells required 94.6 billion. I had always thought an 11 gram pack of yeast had more than enough cells for a low OG beer like this.
If you read the manufacturer specs it’s much less than most are lead to believe.
Posted from a previous forum -
“Some exciting work has been done on dry yeast lately. Reports are coming in of better quality, cleaner dry yeast. Personally, I really prefer the liquid yeasts, but the lure of dry yeast is strong. The biggest benefit is that it is cheap and does not require a starter. In fact, with most dry yeasts, placing them in a starter would just deplete the reserves that the yeast manufacturer worked so hard to build into the yeast. Most dry yeast has an average cell density of 20 billion cells per gram. You would need about 9.5 grams of dry yeast if you were pitching into 5.5 gallons of 1.048 wort to get the proper cell counts. (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. Until I see something different, practical experience tells me this number is correct.) For dry yeasts, just do a proper rehydration in tap water, do not do a starter.”
That Mr. Malty blurb has been floating around for a long time with very little solid background info (that I’ve seen) to back it up.
The dry yeast manufacturers are quoting numbers far below that WITH rehydration so it becomes a matter of whose opinion you trust.
Fact: A pack of dry yeast contains twice as many live cells as you need for 5 gallons of standard gravity wort.
My experience agrees with this. Dry yeast mfgrs. publish their minimum live cells per gram. The actual seems to be three to four times that.
I’ve always heard this and planned with it. I thought it was interesting when I saw the calculator results.
This whole dry yeast cell per gram thing is odd. What is the basis for 20 B/g? An old exchange between Dan Listermann and Dr. Cone, Zainasheff references that same conversation and his own cell counts (plus the cell counts of other, with no references) and Sean Terrill’s viability experiment.
I think Ockham’s Razor applies here: you have to make a ton of assumptions for 20 B/g to be true:
1.) Dr. Clayton Cone WAS NOT talking about wine Yeast.
2.) JZ’s innumerable cell counts were valid.
3.) Sean Terrill’s cell counts were valid.
4.) Dry yeast manufacturers give you 300% extra cells because they assume you won’t follow directions.
On the other hand, you do t have to make any assumptions to trust the manufacturers technical specifications.
I say this knowing that I have never count dry yeast cells, which is something I may do here soon.
I of course could be totally off base here…
So does dry yeast make beer that tastes great or less filling? ;D The debate rages on!
It would be really nice to get another data point on dry yeast (Abbaye) so I would encourage you to count if you can. Personally, I am in the dry yeast has roughly 2X cells of wet camp and think it is unwise to OCD about the cell count. What’s next, counting it for every brew???
I’m in the “trust but verify” camp. There is no industry in the world that’s going to give 300% extra of something if they don’t have to!
I’m waiting on a follow up response from Lallemand and I’ll be grabbing some Abbaye and some of their conditioning/bottling yeast as well.
I don’t have an LHBS but I’d be happy to count anything you want to ship to me. What, am I supposed to have a microscope and not play with it? 
I might take you up on that but sooo many irons in the fire. I happen to be friends of my LHBS owner so I have a shot at acquiring some for a study like this. Just like the LO2 movement, I am confident we will eventually get a better understanding of what’s going on with dry yeast. Personally I think the larger pitch rate is causing some of the “less expressive” comments we see. I think we might be better off not rehydrating and pitching direct to get cell counts in proper range. I only rehydrate for bigger beers.
There may be efficiencies in packaging or something along those lines that result in an optimum packaged size of ~11g. If dry yeast packages were 1/2 the size they are there wouldn’t be a lot in them. Who knows? Retail sales have a whole psychology to them that I care not to understand.
I’m sorry to be the guy who wanders off topic, but I bought some of the Lallemand CBC yeast a bit ago - can’t remember exactly why - and I have a question about , if you’re buying some I’m guessing you might be familiar with it. My understanding is that it is intended to be added post fermentation, at bottling or kegging. My question is, if this yeast is more attenuating than the fermentation yeast, how can one calculate the correct amount of fermentable sugars to use for priming, if you don’t know how much attenuation of the residual sugars remaining in the beer will take place? In other words, if CBC provides significantly higher attenuation than the original yeast, and you prime as you would for the original yeast, don’t you risk bottle bombs?
It doesn’t quite work like that. The yeast attenuation isn’t a factor in the calculations for priming. Priming calcs are temperature and extract based. The assumption in priming calcs is that ALL of the sugar added is fermentable so the conditioning yeast attenuation is inconsequential.
It’s my understanding that the bottling yeasts were - at least in part - selected for their ability to settle out into a tight layer on the bottom of the bottle. Not as easily disturbed as other yeasts, I guess.
+1 and to me that means high flocc’r, less attenuation, and less risk of bottle bombs.
I would have to disagree. If the original yeast is low attenuating and doesn’t ferment some types of sugars and the conditioning yeast eats those plus the added sugar, you get gushers.
The assumption is that unless you are bottling with remaining extract, or adding extract, that you are at Final Gravity when you bottle.
The yeast I referenced was Lallemand’s CBC-1 which is meant to be used with sucrose and dextrose. It does not ferment maltotriose.