White Labs and manufacture date

[Erik the Anglophile]

So, I have two pure pitch packs of whitelabs yeast, and I am looking around at brewersfriends starter calculator to get a sense of what starter I need to make for my 2 coming brews. The first I'm about to use has an expiring date of april 24, the other may 6. I've been googling around and the info is a bit conflicting. Do I backtrack 4 or 6 months to get the manufacture date to calculate the starters on?

 

[VikeMan]

I think they are currently using 6 months after manufacture as the best buy date. But I can't swear to that, or that it's that way for all strains. You can get information about the lot # your particular pack came from at this link:

White Labs Lot # Info

The info at that link doesn't actually list a manufacture date, but it does show a "QC Release Date" which I think is basically the same thing, or close enough.

Why the h*ll they can't just put the date on the package? Beats me.

 

[jdauria]

If you use the link Vikeman posted, put in the lot number, ou will get the date to use as the "package" date and it will show the cell count per mL at the test date...take that cell count number and multiply by 40 (by 35 if it's a vial and not a pure pack) to get the number of cells, in millions, that was in the yeast pack as of test date....sometimes it's over 100 million, sometimes it's under. Then put that date and that cell count in a yeast calculator. Also White Labs claims that their testing shows that their pure packs degrade at a much lower rate than yeast calculators say. If you check this link out, they say at 6 months, they are looking at 71.59% viability, but a yeast calculator will most likely tell you viability is zero after 6 months. Upholding Innovation & Quality: The PurePitch® Shelf Life | White Labs

 

[Erik the Anglophile]

I think they are currently using 6 months after manufacture as the best buy date. But I can't swear to that, or that it's that way for all strains. You can get information about the lot # your particular pack came from at this link:

White Labs Lot # Info

The info at that link doesn't actually list a manufacture date, but it does show a "QC Release Date" which I think is basically the same thing, or close enough.

Why the h*ll they can't just put the date on the package? Beats me.

I found a qc date that seems reasonable to assume is pretty close to mfg date. Not putting the mfg date on the yeast pack is a bit retarded, yes.

 

[Erik the Anglophile]

If you use the link Vikeman posted, put in the lot number, ou will get the date to use as the "package" date and it will show the cell count per mL at the test date...take that cell count number and multiply by 40 (by 35 if it's a vial and not a pure pack) to get the number of cells, in millions, that was in the yeast pack as of test date....sometimes it's over 100 million, sometimes it's under. Then put that date and that cell count in a yeast calculator. Also White Labs claims that their testing shows that their pure packs degrade at a much lower rate than yeast calculators say. If you check this link out, they say at 6 months, they are looking at 71.59% viability, but a yeast calculator will most likely tell you viability is zero after 6 months. Upholding Innovation & Quality: The PurePitch® Shelf Life | White Labs

That's probably under absolutely optimal storage conditions right? Not what your average homebrewer can accomplish in their kitchen fridge. I guess it's safest to count on a fair degree of degradation in viability?

 

[VikeMan]

That's probably under absolutely optimal storage conditions right? Not what your average homebrewer can accomplish in their kitchen fridge. I guess it's safest to count on a fair degree of degradation in viability?

I would certainly look at their viability data as absolute best case.

 

[Holden Caulfield]

If you check this link out, they say at 6 months, they are looking at 71.59% viability, but a yeast calculator will most likely tell you viability is zero after 6 months. Upholding Innovation & Quality: The PurePitch® Shelf Life | White Labs

Just doubling down on noting the significance of White Labs packaging. Yeast calculators viability calculations are substantially lower than what White Labs claims about their new packaging which was introduced in 2017.

Amazingly, I have only found one study that actually evaluated White Labs new packaging claims. Below is a link to a study that compared the viability of White Labs versus Wyeast packaging. Spoiler - White Labs new packaging delivers what they claim.

https://ashevillebrewers.com/blogs/news/yeast-viability-looking-at-expired-yeast

 

[Erik the Anglophile]

Hmm, I might try and make the starter a bit smaller than brewersfriend suggest. If I should end up with a bit too much yeasties,that's no big deal right?
As I understand it, to over pitch in any amounts that might affect the beer negatively, as a homebrewer, requires a rather extreme overpitch.

 

[VikeMan]

Hmm, I might try and make the starter a bit smaller than brewersfriend suggest. If I should end up with a bit too much yeasties,that's no big deal right?
As I understand it, to over pitch in any amounts that might affect the beer negatively, as a homebrewer, requires a rather extreme overpitch.

In general, I'd say it's better to overpitch than under pitch, but I still think it's important to target the ideal rate, whatever that means for the brewer and the beer. i.e. I think it can be an oversimplification to think in binary terms of "small overpitch ok, big overpitch bad." Like most things in brewing, there's a continuum.

I looked at the Brewer's Friend calculator and it doesn't seem to have any kind of override for viability %. But I suppose you could just fudge the age input to hit the viability you think you have.

 

[jdauria]

That's probably under absolutely optimal storage conditions right? Not what your average homebrewer can accomplish in their kitchen fridge. I guess it's safest to count on a fair degree of degradation in viability?

True, doubt it will the same, but can assume it's also not 0% after 6 months as most yeast calculators would say.

 

[Holden Caulfield]

I looked at the Brewer's Friend calculator and it doesn't seem to have any kind of override for viability %.

The yeast calculator below allows for viability. It is very simple to use and allows for selecting different models for growth factors that were developed by Zainasheff and Troester and Chris White. Link and snapshot below. Can't vouch for accuracy, all I can say is that my beers turn out quite tasty.

http://yeastcalculator.com/

 

[jdauria]

I looked at the Brewer's Friend calculator and it doesn't seem to have any kind of override for viability %. But I suppose you could just fudge the age input to hit the viability you think you have.

Under part two, on the calculator, you can just manually enter in a starting cell count rather than have it calculate from step 1, that would work the same I guess if you calculate viability yourself.

 

[Erik the Anglophile]

I'll calculate on about 50% viability, that should put me in the ballpark if whitelabs viability improvements are to be somewhat trusted.

 

[VikeMan]

True, doubt it will the same, but can assume it's also not 0% after 6 months as most yeast calculators would say.

I don't know why any calculators would estimate 0% at 6 months. BrewCipher, e.g. estimates 28% at 180 days (using the default death rate, which itself is user adjustable).

 

[jdauria]

I don't know why any calculators would estimate 0% at 6 months. BrewCipher, e.g. estimates 28% at 180 days (using the default death rate, which itself is user adjustable).

I know it's one thing that some yeast calculators are not great at. If you scroll down on Brewer's Friend one, they give the logic that liquid yeast dies off at a 21% rate per month, or 0.7% per day, so that they say it has zero viable cells at about 4.75 months.

 

[VikeMan]

I know it's one thing that some yeast calculators are not great at. If you scroll down on Brewer's Friend one, they give the logic that liquid yeast dies off at a 21% rate per month, or 0.7% per day, so that they say it has zero viable cells at about 4.75 months.

BrewCipher also defaults to 0.7% per day. But it's 0.7% of the remaining cells rather than of the original total. The logic is that it's not at all uncommon to cultivate yeast from very old sources, so there is obviously a decrease in numeric deaths per day as you go along. Conceptually, it's similar to a "half life."

 

[Erik the Anglophile]

Did some reading around, and the viability counter for their yeast seems to be somewhat reliable. I'll go with what it lists -10% to account for less than optimal handling procedures during transport etc. Hopefully it will end up somewhat right.