The Great Bottle Opener Giveaway

Home Brew Forums > Home Brewing Beer > Fermentation & Yeast > dry yeast cell counts and viability

Reply
 
LinkBack Thread Tools
Old 05-06-2014, 07:46 PM   #1
stickyfinger
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2009
Location: Poughkeepsie, NY
Posts: 8
Default dry yeast cell counts and viability

Hi, I am going to repost a thread I started at theelectricbrewery.com, just to get some more feedback. (I'm not sure how many people use the other forum.)...

I've been thinking about dry yeast lately, and I've been using the mrmalty.com calculator to determine pitch rates for liquid and dry yeast. Jamil says on his site that dry yeast has 20 billion cells/gram. I've been talking to someone from Fermentis about their dry yeast, because I kept reading that they guarantee 6 billion cells/gram up to two years from production (expiration date.)

I've reaped some very interesting information from the person at Fermentis, if it is all true. I assume this would only apply to Fermentis yeast, though, it MAY apply to other dry yeast.

1) The viability of dry yeast stored in the fridge (+4 degrees C) or the freezer (-4 degrees C) is the SAME.

2) There will be a minimum of 6 billion viable cells per gram up to the best before date on the package of yeast.

3) A 10% loss of viability over the two year storage (if the yeast is stored correctly) would be considered extremely high by Fermentis. So, you are looking at 90%+ viability over the entire useful life of the yeast sachet.

4) Fermentis does not see "any difference" in performance of the yeast with a 10% difference in viability (not sure what they have fermented, but probably a wide range of gravities, etc.)

5) Using the classic methylene blue method for measuring viability in active dry yeast cells will result in very inaccurate results, as they have disorganized membranes and lower capability for pumping out the stain (this would seem to indicate to me that the yeast count would be in fact much higher than results determined using the methylene blue method.)

That is basically the summation of the interesting information I have gleaned. Has anyone (besides Jamil) recently done a methylene blue yeast viability test on a package of dry yeast? If not, maybe I will take it upon myself to do that a few times to see what kinds of counts I am getting and then see if I can use another method appropriate for dry yeast and see what that gives. I had assumed I could just rehydrate the yeast and then do a test on the yeast once it is in good shape with the methylene blue test. I should confirm with Fermentis if this is appropriate.

I specifically asked Fermentis how many cells should be in the sachet, and they keep saying 6 billion, but they never really confirmed that number. they said "if we give you 6 billion cells per gram", so maybe they in fact are giving 20 billion per gram but don't want to say any more than 6 billion for liability or bad storage or something?

I don't have enough experience with dry yeast to know whether the 6 billion number even makes sense in terms of the degree of attenuation experienced with the yeast.

I know some of you probably don't care much what the counts are, but I am just curious and would like to pitch consistently.

__________________
stickyfinger is offline
 
Reply With Quote Quick reply to this message
Old 05-06-2014, 08:09 PM   #2
boydster
Don't act like you're not impressed.
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
boydster's Avatar
Recipes 
 
Join Date: Apr 2013
Location: , Maine
Posts: 2,407
Liked 577 Times on 399 Posts
Likes Given: 453

Default

Regarding cell counts:
http://seanterrill.com/2011/04/01/dry-yeast-viability/
http://seanterrill.com/2011/07/29/dr...lity-take-two/

Regarding yeast's ability to regulate chemicals going in/out of the cell after proper hydration (as done in the experiments above), plus other valuable nuggets of information:
http://koehlerbeer.wordpress.com/200...-clayton-cone/

__________________

Check out these cool kits at Know How Brews & Foods!

Big Jim Walker IIPA
Allagash-ishhh White Ale
Happy Hoppy Blonde Ale

boydster is offline
 
Reply With Quote Quick reply to this message
Old 05-06-2014, 11:43 PM   #3
stickyfinger
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2009
Location: Poughkeepsie, NY
Posts: 8
Default

Thanks for the links, boydster. I was just looking at sean's site when i got your reply! he has a ton of really fantastic data on his site, very impressive. it's good to put some science into homebrewing once itn awhile. That us-05 viability test is pretty damning for the Fermentis conversation I had. i wonder what is up? It fits perfectly with Jamil's advice. I guess for now I'll keep going with the pitching rate calculator and assume that the yeast is 20 billion cells/gram at packaging. I should really test some packs for myself.

__________________
stickyfinger is offline
 
Reply With Quote Quick reply to this message
Old 05-07-2014, 01:07 AM   #4
boydster
Don't act like you're not impressed.
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
boydster's Avatar
Recipes 
 
Join Date: Apr 2013
Location: , Maine
Posts: 2,407
Liked 577 Times on 399 Posts
Likes Given: 453

Default

Another HBT member had posted that a Fermentis rep told them that each packet leaves the production line with an average of 150 billion cells. I've been using that as my baseline guesstimate when using their products. Frankly, though, most times I don't think that difference would be noticeable. If you need 150 billion cells but pitch 200 billion, or vice versa, or need 175 billion and pitch one full packet, I don't think you would notice a difference in the end product due to pitch rate in those circumstances. What was interesting to me about Sean Terrill's experiment was that the viability of the yeast hydrated in water exactly correlated with the expected viability due to the age of the yeast - in other words, he essentially showed that he was able to get almost 100% of the yeast that was still expected to be alive to survive the hydration process by using water instead of wort.

From what I understand, that 6 billion is just a guaranteed minimum, meaning if you had a packet of yeast that was about to expire and it had been stored at room temp, they can still promise that 6 billion cells per gram will be alive.

Happy brewing!

__________________

Check out these cool kits at Know How Brews & Foods!

Big Jim Walker IIPA
Allagash-ishhh White Ale
Happy Hoppy Blonde Ale

boydster is offline
 
Reply With Quote Quick reply to this message
Old 05-07-2014, 02:38 AM   #5
stickyfinger
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2009
Location: Poughkeepsie, NY
Posts: 8
Default

I think you're right about the 6 billion being a minimum. I'm starting to think that is what they are doing with that. I was also impressed with sean's experiment showing that the viability was pretty predictable. It's nice to see that someone took the time to test whether water rehydration or just sprinkling on the wort is better. It seems fairly conclusive that water rehydration is superior, though, some people seem to prefer beer with more off-flavors.

I'm mostly concerned about lager pitching. The proof is in the pudding though. I'll see how my most recent attempt with dry yeast works. I found some Saflager W-34/70 that had an expiration of 9/14. Using the pitching rate calculator, i found that I needed 3 packs per 5 gallon batch. I pitched that much, and we'll see how the beer ferments. If it turns out well, then I will be satisfied. I think ales are more forgiving, but when you get into lagers you need to be more careful maybe. I haven't made too many lagers, mainly due to the pain of getting enough yeast. I will be really stoked if the W-34/70 gives a good lager, as I can just pitch more packs instead of having to make big or step-starters or brew 2 beers in a row to get enough yeast.

__________________
stickyfinger is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Dry yeast viable cell counts angrybits Fermentation & Yeast 7 05-09-2013 03:21 AM
Lab testing for slurry cell counts and viability WoodlandBrew Fermentation & Yeast 8 12-19-2012 12:37 PM
Yeast cell counts jmf143 Fermentation & Yeast 6 08-14-2010 10:30 AM
Regarding Yeast Cell Counts and Bottling Pelikan Bottling/Kegging 5 11-28-2008 12:26 PM
Yeast Cell Counts: Dry vs. Liquid Cistercian General Techniques 9 10-25-2008 01:32 PM