Author Topic: Yeast "Best By" date vs "Package Date" in Beersmith  (Read 6982 times)

Offline OldGoat

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Yeast "Best By" date vs "Package Date" in Beersmith
« on: March 12, 2020, 10:30:33 AM »
I have been using Beersmith for MANY years now and am currently on the latest version (BS3).  Over the last couple of years I have seen that yeast labs have gone from stamping the packaging date on the yeast to instead stamping the "Best By" date.  However, as far as I can tell, BS only has the option of entering the packaging date.  Has anyone figured out the correct way to enter the date that will make the most sense.  With that question out there, I do admit that I don't pay a LOT of attention to that date unless it is very expired.  I make a starter for pretty much every beer I brew and rarely have an issue.   Also, I wonder if anyone knows if a fix is in work to allow us to enter the "Best By" date...

Offline BOB357

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #1 on: March 12, 2020, 07:09:45 PM »
It appears the BeerSmith ages yeast based on the packaging date. IIRC, that would be 90 days before the best by date for liquid yeasts and 2 years for dry. Several yeast manufacturers have stretched out the age they consider their yeasts as still being pitchable for a standard batch. Since the pitching rate and starter tool doesn't specify brand names, we can assume the aging is still calculated in the same manner as in earlier versions.

This way of aging would favor erring on the side of over pitching in most cases. I'd rather this than the opposite, especially since most of us don't know how the yeasts were handled and stored before they came into our hands. Many homebrewers believe that vitality is much more important than cell count and report good results using vitality or SNS (shaken not stirred) starters. Likely the same reason some yeast manufacturers have stretched out the acceptable ageor their ueasts, maybe improving something in their process allowing them to assure acceptable viability/vitality for a longer time. We can only hope.

Bob

Offline Kevin58

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #2 on: March 13, 2020, 06:45:44 AM »
Quote
IIRC, that would be 90 days before the best by date for liquid yeasts

I heard a podcast either from Denny and Drew or Marshall Schott where they mentioned that Imperial says their yeast viability is 4 months or longer.
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Offline Oginme

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #3 on: March 13, 2020, 07:07:14 AM »
One of the several reasons I have tended to stay away from White Labs when using liquid yeast.  There is no clear indication on the web site as to the relationship between 'best by' date and manufacturing date.  The best info I have seen is that they label packets as 6 months for home brew sized packets and 3 months for commercial pitches.  This comes from someone on another forum who works at White Labs in a question on this very same issue.  Not quite sure why the difference, though they may seem to think that home brewers are less sensitive to under pitching due to the smaller batch sizes.
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Offline merfizle

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #4 on: March 13, 2020, 07:53:00 AM »
I don't use White Labs for that reason plus due to the fact it doesn't really contain the advertised amount of yeast.
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Offline Oginme

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #5 on: March 13, 2020, 08:12:52 AM »
I don't use White Labs for that reason plus due to the fact it doesn't really contain the advertised amount of yeast.

While I cannot say that specifically, the packages I tested for cell count were all at the very minimum of acceptable cell counts.  I only counted three packets of the pure pitch, but ended up with an average of 102 B cells in the packet with the highest being 104 Billion.  I have never counted a Wyeast smack pack (9 samples) at less than 106 Billion cells.
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Offline mister2

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #6 on: August 25, 2020, 11:17:47 AM »
I just purchased a packet of Wyeast that shows a best before date of 2-15-2021.  It was suggested above that the manufacture date is 90 days prior to the Best Before date which would put it around 11-15-2020, but that date has not come yet (today is 8-25-2020), so the 90 day rule doesn't work out if I understood BOB357's post correctly.  Does anyone have more accurate info on Wyeast manufacture dates based on the Best Before date?

Offline enkamania

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #7 on: August 25, 2020, 11:34:33 AM »
For White Labs, go to https://classic.yeastman.com/Login/Public/Report/PublicLabQCResult.aspx and put in the lot #, it will give you the QC release date and othe information.

Offline Oginme

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #8 on: August 25, 2020, 11:42:53 AM »
You would need to query Wyeast on that.  So far, I have not purchased a packet which does not have the manufacturing date printed on it.  I am certainly sorry they followed White Labs and switched the designation, but I can sort of understand some of the thinking behind it.

I have found that the yeast calculators (including the one in BeerSmith) over estimates the loss of cell viability in the liquid yeast packages.  Case in point, I picked up a packet of WY1272 for use last Sunday which had a manufactured on July 16, 2020.  By the yeast calculator in BeerSmith it gave me a viability of 71.2%.  I counted around 98%+ viable cells (109 Billion cells total)when I opened up the packet to add it to a starter wort last Thursday.  Add to that the fact that they typically add more than the 100 billion cells (from all of my counting) and they are projecting that a properly stored package of yeast would have approximately 100 billion viable cells after 3 months or so after manufacture. 

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Offline mister2

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #9 on: August 25, 2020, 12:27:02 PM »
According to my HBS owner, Wyeast just switched over to using the "Best If Used By" date as opposed to the date of manufacture.  He will speak with his Wyeast rep and get clarification on the actual date of manufacture, but he thinks it is 6 months prior to the Best If Used By date.  This info is not on the Wyeast web site under their FAQ section, and commoners such as myself don't have access to their customer service unless you are a retail or commercial customer.  I'll report back if/when I get the answer.

Offline BOB357

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #10 on: August 25, 2020, 12:35:28 PM »
I just purchased a packet of Wyeast that shows a best before date of 2-15-2021.  It was suggested above that the manufacture date is 90 days prior to the Best Before date which would put it around 11-15-2020, but that date has not come yet (today is 8-25-2020), so the 90 day rule doesn't work out if I understood BOB357's post correctly.  Does anyone have more accurate info on Wyeast manufacture dates based on the Best Before date?

My statement, see below, was in regards to how BeerSmith ages yeasts and has nothing to do with how the various manufacturers do it.

"It appears that BeerSmith ages yeast based on the packaging date. IIRC, that would be 90 days before the best by date for liquid yeasts and 2 years for dry. Several yeast manufacturers have stretched out the age they consider their yeasts as still being pitchable for a standard batch. Since the pitching rate and starter tool doesn't specify brand names, we can assume the aging is still calculated in the same manner as in earlier versions."

Bob

Offline mister2

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #11 on: August 25, 2020, 02:53:33 PM »
Based on your comment...

"It appears that BeerSmith ages yeast based on the packaging date. IIRC, that would be 90 days before the best by date for liquid yeasts and 2 years for dry. "



...that sounds to me that you are indicating the packaging date is "90 days before the best by date for liquid yeasts", but I must be misunderstanding. 

Since the packaging date is the important factor, I would just like to be able to determine exactly what it is so that BS calculates its viability correctly.  I see others also have this same question but have not seen any guidance on the recent change specific to Wyeast.

Offline BOB357

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #12 on: August 25, 2020, 03:46:51 PM »
Exactly, how BeerSmith calculates the aging has no correlation to how various manufacturers age it. Are you aware of a pitch rate calculator that is aligned with the different ways individual manufacturers do and keep up with all of the changes?
Bob

Offline CheersToGreatBeers

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #13 on: August 31, 2020, 06:43:45 PM »
I have been using Wyeast Smack Packs for a number of years.  To calculate starter sizes, I enter the Wyeast "Mfd Date" into Beersmith.  I understand that the viable cells reduce by approximately 20% each month after the "Mfg Date".

I picked up 3 packs of Wyeast from my LHBS on 8/22/2020.   They included the "Best if Used By Dates" of:
2/15/2021
2/19/2021
2/28/2021

I was previously told on a forum and by my LHBS to count back 6 months to learn the Mf'd date.

For these 3 packs, counting 6 months back,  to learn the Mfd date, they would be:
8/15/2020
8/19/2020
8/28/2020

Since 2 of the calculated "MFd" dates are within one week of picking up the yeast and 1 date is after I picked-up the yeast, it is clear that counting back 6 months from the "Best if Used By Date" does not work.

I have follow-up inquiry to my LHBS.

Offline Oginme

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Re: Yeast "Best By" date vs "Package Date" in Beersmith
« Reply #14 on: September 01, 2020, 05:57:50 AM »
I understand that the viable cells reduce by approximately 20% each month after the "Mfg Date".


This is where you are mistaken.  While this may have been the case 14+ years ago when most of the yeast calculators we use today were developed, the world does not remain static.  Like all manufacturers, the yeast companies have made process improvements and lengthened the shelf life, viability, and survival rates of the liquid yeasts.  This really throws all the calculators out the window when it comes to predicting the number if viable cells based upon manufacturing dates. 

If you look back at my last post, I had a cell count of 109 billion cells with a viability of 98% (rounding down) which would give me 106.8 billion viable cells in the package at 5 weeks old.  Projecting this out, at 6 months (26 weeks) the viability would have dropped around 10%.  This would equate to 98 billion cells in the package.  Given my counting variability of +/- 3 billion cells and assuming that commercial packages are all the same, I would contend that they plan on at least 100 billion cells at the best buy date on the package. 

I also would suggest that the use by dates are calculated to the particular strain, which is why you may get different ranges based upon each strain.   

The starter calculators are highly variable in their predictions versus your actual results since everyone will make a starter just a little bit differently (volume variations, DME variations, access to O2, time on stir plate, rate of agitation, etc).  Unless you are performing yeast cell counts at the time of pitching, you really do not know how many cells you are actually tossing into the fermenter.

Basically, I have gone away from using the viability the yeast starter calculators predict and, since I have the equipment, do my own cell counts when I need to ensure a given pitch rate.  My recommendation would be to use the "best if used by" dates as the manufacturing date and assume that you have around 100 billion cells at that point or anytime leading up to that date.

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