Author Topic: Wyeast MFg Date July 1st  (Read 212 times)

Offline levm38

  • 1st Kit
  • *
  • Posts: 4
Wyeast MFg Date July 1st
« on: August 24, 2020, 10:32:45 AM »
Hello

I just got one Wyeast Yeast and it says Mfg July 1st 2020.

How much percentage is lost per month? is there a calculator for this?  PLease note its a Smack Pack.


Thanks

Offline 4dogbrewer

  • Cellarman
  • **
  • Posts: 31

Offline levm38

  • 1st Kit
  • *
  • Posts: 4
Re: Wyeast MFg Date July 1st
« Reply #2 on: August 24, 2020, 12:28:56 PM »
what does it mean Mfg + 0.5 ??

so the viability of my yeast is 64% only! 54 days old :(

Offline goose

  • Brewmaster
  • *****
  • Posts: 832
Re: Wyeast MFg Date July 1st
« Reply #3 on: August 24, 2020, 01:37:12 PM »
I used to get all hung up on viability numbers (predicted by brewing software) with various yeasts that I have used.  I don't worry about that anymore.  Obviously I try to use it by the manufacturer's "best by date" as a precaution.  However, if you make a starter, you will be fine.  I have had some yeast that was almost three months old, made a starter, and had active fermentation in about 4-6 hours.  Denny posted a while back that he made a beer with a yeast that was 2.5 years old just to see what would happen and it came out fine.
With dry yeast they can be a year or so old and they will still be fine.  And no, I do not rehydrate them
Goose Steingass
Wooster, OH
Society of Akron Area Zymurgists (SAAZ)
Wayne County Brew Club
Mansfield Brew Club
BJCP Certified
AHA Governing Committee Member

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 22925
  • Noti OR [1991.4, 287.6deg] AR
    • Dennybrew
Re: Wyeast MFg Date July 1st
« Reply #4 on: August 24, 2020, 01:40:13 PM »
Hello

I just got one Wyeast Yeast and it says Mfg July 1st 2020.

How much percentage is lost per month? is there a calculator for this?  PLease note its a Smack Pack.


Thanks

Not enough to worry about in that short time.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 22925
  • Noti OR [1991.4, 287.6deg] AR
    • Dennybrew
Re: Wyeast MFg Date July 1st
« Reply #5 on: August 24, 2020, 01:41:21 PM »
I used to get all hung up on viability numbers (predicted by brewing software) with various yeasts that I have used.  I don't worry about that anymore.  Obviously I try to use it by the manufacturer's "best by date" as a precaution.  However, if you make a starter, you will be fine.  I have had some yeast that was almost three months old, made a starter, and had active fermentation in about 4-6 hours.  Denny posted a while back that he made a beer with a yeast that was 2.5 years old just to see what would happen and it came out fine.
With dry yeast they can be a year or so old and they will still be fine.  And no, I do not rehydrate them

Like Mark has pointed out many times, it's about yeast health, not cell count.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline Megary

  • Brewer
  • ****
  • Posts: 330
Re: Wyeast MFg Date July 1st
« Reply #6 on: August 24, 2020, 01:43:08 PM »
I used a 6-7 month old smack pack of WY1450 that the calculators told me had 0% viability.  It fermented just fine.

I would say that if you smack the pack and it blows up, your'e good to go.

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 22925
  • Noti OR [1991.4, 287.6deg] AR
    • Dennybrew
Re: Wyeast MFg Date July 1st
« Reply #7 on: August 24, 2020, 01:45:40 PM »
I used a 6-7 month old smack pack of WY1450 that the calculators told me had 0% viability.  It fermented just fine.

I would say that if you smack the pack and it blows up, your'e good to go.

Yep.  That's the purpose of a smack pack.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline Steve Ruch

  • Senior Brewmaster
  • ******
  • Posts: 1353
Re: Wyeast MFg Date July 1st
« Reply #8 on: August 24, 2020, 05:48:18 PM »
I used to get all hung up on viability numbers (predicted by brewing software) with various yeasts that I have used.  I don't worry about that anymore.  Obviously I try to use it by the manufacturer's "best by date" as a precaution.  However, if you make a starter, you will be fine.  I have had some yeast that was almost three months old, made a starter, and had active fermentation in about 4-6 hours.  Denny posted a while back that he made a beer with a yeast that was 2.5 years old just to see what would happen and it came out fine.
With dry yeast they can be a year or so old and they will still be fine.  And no, I do not rehydrate them
I just fermented a mild with Munton's yeast dated 11/16 that turned out fine. I didn't rehydrate or aerate.
Crescent City, CA

I love to go swimmin'
with hairy old women

Offline Randall Miller

  • 1st Kit
  • *
  • Posts: 5
Re: Wyeast MFg Date July 1st
« Reply #9 on: September 01, 2020, 12:57:45 AM »
I use the starter calculator in Beersmith.  I understand that this calculator uses a combination of the following to calculate the needed starter size:
- Mfg date of of the liquid yeast.
-Brew date
-OG
- May be some other factors

I believe that the software estimates that the viable yeast cells diminish by about 20% per month. 

I plan ahead so my LHBS can have available Wyeast packs that have been manufactured within 2 months of my brew day.  So far, this has worked well for me.

Offline Saccharomyces

  • Brewer
  • ****
  • Posts: 381
Re: Wyeast MFg Date July 1st
« Reply #10 on: September 01, 2020, 06:55:01 AM »
Please throw the yeast cell calculators out with the trash, as they are next to worthless. There is absolutely no way to calculate the viability of a yeast culture and anyone who tells you that you can does not know what he/she is talking about. Yeast cultures are a heck of a lot more robust than most brewers believe. My whole beef with brewing software is that it attempts to achieve a level of precision that does represent reality. The only way to determine viability is to count viable cells using a microscope and a hemocytometer.

In practice, it is never a good idea to pitch a liquid culture that is more than a week or two old without first making a starter. Making a starter is not so much about increasing cell count, as it is about increasing cell health. The yeast biomass grows at a rate of 2^n, where the symbol “^” denotes raised to power of; therefore, it does not take very long for for a small number of yeast cells to become a very large number of yeast cells. What is important is sanitation because bacteria also grows exponentially and its replication period is 1/3rd that of yeast; therefore, the bacteria biomass grows by a factor of 8 every time the yeast cell count doubles.