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General Category => Yeast and Fermentation => Topic started by: Saccharomyces on December 10, 2021, 03:23:49 pm

Title: Wyeast Expiration Dates are Conservative
Post by: Saccharomyces on December 10, 2021, 03:23:49 pm
This package of Wyeast expired on June 20, 2021.  I smacked the smack pack a couple of days ago.   These photos should be enough proof that Wyeast expiration dates are conservative on average.


(https://i.imgur.com/988fjRJ.jpg)

(https://i.imgur.com/Huita1z.jpg)
Title: Re: Wyeast Expiration Dates are Conservative
Post by: brewthru on December 10, 2021, 03:35:28 pm
Last December I had a completely different experience. My pack of California Common expired in October. For numerous reasons I didn't get around to using until late December. Noted the pack didn’t swell. I thought "No, big deal. I'll make a starter.". I make a small starter using the yeast. I didn’t see any activity. Stepped up to a larger stater. Still no activity. OK, “Jim, it’s dead!”. Went to a local HBS and purchased a new pack of California Common liquid yeast.
Title: Re: Wyeast Expiration Dates are Conservative
Post by: Saccharomyces on December 10, 2021, 03:47:04 pm
Last December I had a completely different experience. My pack of California Common expired in October. For numerous reasons I didn't get around to using until late December. Noted the pack didn’t swell. I thought "No, big deal. I'll make a starter.". I make a small starter using the yeast. I didn’t see any activity. Stepped up to a larger stater. Still no activity. OK, “Jim, it’s dead!”. Went to a local HBS and purchased a new pack of California Common liquid yeast.

If a smack pack does not swell, it is not viable. That is usually a sign of poor handling, usually between Wyeast and a LHBS.  However, a lot of LBHS are not adept when it comes to handling yeast correctly. It could be a case where the culture was shipped during the warm months.  In that case, all bets are off.  I avoid purchasing liquid cultures that were shipped after the beginning of April.   That rule does not guarantee viability, but it lowers the chance of getting a culture that prematurely ages.  What I know is that if a culture is shipped during the cool months and is immediately refrigerated upon receipt and kept refrigerated until used, its shelf life is much longer than what is printed on the pack.
Title: Re: Wyeast Expiration Dates are Conservative
Post by: brewthru on December 10, 2021, 04:40:06 pm
I'm trying to learn the proper handling and that’s why I’m asking the following.

You purchase all liquid yeast prior to the end of April? Am I correctly understanding? How long are these good?

What about the insulated/chilled packs some online retailers offer for shipping the liquid yeast? These these work or not? I guess not, based on the April deadline.
Title: Re: Wyeast Expiration Dates are Conservative
Post by: Richard on December 10, 2021, 05:29:05 pm
An ice pack will work for a day or two, depending on the temperature of the truck it is in. In the winter you might not need one. In the summer you might get fast enough shipping that the ice pack will do, maybe not. I have had bad experiences with shipping liquid yeast so I will only get it from my local store, where I know it has been handled well. I shop at the Los Altos MoreBeer, which gets a truck delivery from their warehouse every Friday. It is only a few hour drive and everything that needs to be refrigerated is kept cold during the trip. I have never had a problem with the liquid yeast I get from them.
Title: Re: Wyeast Expiration Dates are Conservative
Post by: RC on December 10, 2021, 06:21:36 pm
To me, it's also proof that the smackpack is rather useful for confirming viability and more than just a gimmick.
Title: Re: Wyeast Expiration Dates are Conservative
Post by: Saccharomyces on December 11, 2021, 11:43:11 am
To me, it's also proof that the smackpack is rather useful for confirming viability and more than just a gimmick.

Absolutely! It also makes waking up a commercially produced liquid yeast culture an aseptic process.   The culture is out of quiescence when it is pitched into starter medium.  That is not true with liquid cultures from other propagators.