How did I kill my yeast?

I brewed a 3 gallon batch of Weizenbock yesterday. Anticipating an OG around 1.080, I decided to build a starter from my smack pack of Wyeast 3638. I took the yeast out of the refrigerator at around noon on Saturday and broke the nutrient package before leaving the house to visit a friend. Unfortunately, the visit lasted much longer than expected. When I got home, the package had swelled fully but I wasn't ready with the wort for the starter. So I put the yeast back into the refrigerator in its still-sealed package and quickly boiled 3/4 liter of water with about 3 oz of DME. I then put the flask into the refrigerator as well, with the intent of pitching the yeast into the starter before going to sleep.

So of course, my first thought on waking the next morning was "Oh crap, I forgot to pitch the yeast." I quickly removed everything from the fridge, sprayed the smack pack with some StarSan, gave it a good shake and then added it to the flask. But after six hours on the stir plate, there was still no visible activity in the starter.

By that time, I'd finished boiling and cooling the wort, and it turned out that I had an OG of only 1.067. I decided that there was nothing to be gained by waiting any longer for the starter, particularly given the lower gravity of the wort -- so I did.

It's now been almost 20 hours, and there's no sign of activity in the fermenter. While I know it's possible that I haven't waited long enough, the lack of activity in the starter makes me thing that I've probably killed the yeast. My previous starters (admittedly, with other strains) have all reacted much more quickly.

Could I be wrong about that?

And if not, what's likely to be the mistake I made that killed the yeast? I'm assuming, of course, that the swelling of the smack pack was sufficient evidence of the yeast's previous viability.

 

I say wait it out. I have not used that precise strain, but I do make a wheat/rye beer regularly that I bounce back and forth between the white labs hefeweizen, American hefeweizen, and the safale dry wheat yeast (06 I think). All 3 of those, even the rehydrated dry yeast, start significantly slower than more "standard" ale strains. I once pitched a liter starter of the American strain at high krausen an still had about 16-18 hours lag on a 1.048 beer.

I even bought a pack of dry yeast on the way home from work that day, only to arrive at the house to find the beer chugging along nicely.

If you kept your process clean, you should not have any issues. It's been my experience that wheat yeasts are slow starters. At 1.067, you may just need to wait a bit longer.

 

Even with the lack of activity in the starter, the odds are good that your yeast is fine. You are panicking way too soon. RDWHAHB.

 

One other thing I finally did to ease my worry, buy a pH meter. Acidity becomes more acidic during fermentation. I take a pH reading going into the fermenter. If I am worried that there is something amiss a few hours or even a day later, I take a small sample with a sanitized wine thief and measure pH again

A measurable drop in pH means the yeast are working, even if I can't see them.

 

When you put the yeast and the starter wort in the refrigerator you put the yeast to sleep. Since you did not wait for the starter to warm up and ferment you essentially pitched just the smack-pack while those yeast cells were dormant.

Even with the lower gravity of 1.067 you needed a fairly large starter.

Your yeast now need to reproduce to cell counts sufficient to ferment the wort before they will get into full fermentation mode.

I would not be surprised for this one to take 2-4 days to kick off.

I would also say that you did not kill the yeast. So patience is needed in this case.

 

Patience wins the day! I just got home to find a monster krausen in the fermenter.

 

Never underestimate the power of RDWHAHB.

I'm happy for you and your beer. Cheers!

 

Yeast is yeast. Its like a weed in other controlled environments.