[gav]

Just opened 2 packs of WLP500 with a Best By date of 4/15/20 (mfg date 10/17/19, 86% viability per my calcs), and both liquid packs were med-dark brown. I'm used to seeing a creamy white or off/white yeast slurry, and I'm concerned that the yeast might be dead, or partially dead.
Just pitched a 2L starter with Light Pilsner DME, and the starter wort is brown. There was no funky smell when packs were opened and pitched, but no yeasty smell either.

I just got off the phone with WL, and they say this is normal, as they sometimes switch out their propagation wort from DME to grain-based and vice-versa. Seems a little weird to me, as I assumed labs separate yeast from propagation starter before release, just as many homebrewers do with water after harvesting.

I've heard from a local pro brewer that large yeast mfgrs sometimes dump bad batches on the Homebrew market - though WL seems to be pretty upstanding. They have dropped the mfg date on their packaging (very common these days in food-and-wine packaging) - really bugs me with packaged craft beers (don't get me started on coffee roast dates!) - but they are very transparent about the mfg (QC) date if you take the trouble to enter the printed Lot# on their yeastman.com website (QC link)
I'm going to wait to see if the starter takes off, but I have no reliable means to get a cell count for pitching if the starting viable cell count was off. WL said they stand by their product and offer a replacement guarantee if it is defective, but I hate to ruin a whole batch finding out.

Any thoughts?

[denny]

You got the answer from White Labs.  What the brewer told you is not based on fact.

[BrewBama]

Did the starter perform well?


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[ynotbrusum]

I find it hard to believe that any yeast lab would "dump" defective product into the homebrew market.  I would believe that handling and shipping could render a yeast package unusable.

[denny]

I find it hard to believe that any yeast lab would "dump" defective product into the homebrew market.  I would believe that handling and shipping could render a yeast package unusable.

I can tell you with 99.9% certainty that doesn't happen.  We get the same products that everyone else does.

[hopfenundmalz]

Define a bad batch of yeast.

Many smaller breweries will propagate from a pack or two if they have time. They have plenty of wort.

[tommymorris]

I've heard from a local pro brewer that large yeast mfgrs sometimes dump bad batches on the Homebrew market

Any thoughts?

No business would do this. They would ruin their reputation.

[gav]

Reporting back. After 24 hrs (starter on a stir plate at 69 deg room temp, 2 packs of WLP500 in 2L of 1.036 wort), there is and was NO signs of fermentation. Gravity reading is still 1.036 one day later. This yeast is dead as a doornail.
I'm going to chuck it and go find myself some new yeast.

edit: After speaking with my LHBS, I'm going to let this sit in the fridge for 12 hrs, and then visually examine the volume of the yeast slurry after it settles out. According to the vendor, gravity does not need to drop for cell multiplication.

[gav]

Final report Day 3. After 24 hrs in the refrigerator, there is no yeast cake in the bottom of the flask. Wort is a bit lighter after settling, but not clear. The very thin layer of yeast when viewed from the bottom is dark brown and much darker than the wort.
This lot of yeast is definitely not healthy, if not dead.
I've followed the same best practices for making a starter I've used successfully multiple brews. My first dud.

Anyone have an opinion on the statement "starter gravity does not need to fall in order for yeast cells to multiply"?

My understanding is that during replication in an aerobic environment, yeast converts O2 and sugar to CO2 and H2O, as opposed to converting sugar to CO2 and C2H5OH (ethanol) during anaerobic fermentation. Even if the starter activity was purely aerobic, it looks to me that sugar depletion (without alcohol creation) would still lower the gravity.

[denny]

Final report Day 3. After 24 hrs in the refrigerator, there is no yeast cake in the bottom of the flask. Wort is a bit lighter after settling, but not clear. The very thin layer of yeast when viewed from the bottom is dark brown and much darker than the wort.
This lot of yeast is definitely not healthy, if not dead.
I've followed the same best practices for making a starter I've used successfully multiple brews. My first dud.

Anyone have an opinion on the statement "starter gravity does not need to fall in order for yeast cells to multiply"?

My understanding is that during replication in an aerobic environment, yeast converts O2 and sugar to CO2 and H2O, as opposed to converting sugar to CO2 and C2H5OH (ethanol) during anaerobic fermentation. Even if the starter activity was purely aerobic, it looks to me that sugar depletion (without alcohol creation) would still lower the gravity.

Of course the gravity will fall as the yeast multiplies

[BrewBama]

Sorry to hear about your negative experience.

This is an example of one of the reasons I went with dry yeast exclusively: Zero frustration. I experienced DOA liquid yeast one too many times.


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