Yeast not active

[Brewer #356985]

Hi,
I started a brew session last weekend and pitched a yeast that wont get started. Yesterday i pitched in new yeast that is active and working. I control the gravity with a tilt and I can see that it´s changing but very slowly. Normally the gravity drops fast in the beginning and in the end more slowly. Should I be worried for the slow progress or just wait and see what happens? I am brewing a lager with Wyeast Bohemian Lager 2124 yeast. I should also mention that i ferment under pressure.
/Martin

 

[Sandy Feet]

How much did you pitch and at what temperature? Lagers need a BIG pitch. If you pitch big, AND the yeast is healthy and not out of date, they will start fast. If not, they won't.
What is the expiration date on the yeast?

 

[BarbarianBrewer]

In addition to the questions that @Sandy Feet asked, what was the OG and volume of the beer? I would recommend using a yeast pitching calculator to see approximately how much yeast you need. You don't need to be spot on; just in the ball park. I used the calculator & entered in typical values for a lager. I selected a 100B/pack liquid yeast that was 2 months old. (Age is much more important for liquid yeast than dry). You can see below that the calculator guesses that only 60% of the yeast are healthy. It also shows that if I pitch that yeast into 6 gallons of 1.048 OG wort that I'm only pitching 15% of the desired amount of yeast. So this would call for either additional packs of yeast or a yeast starter. Also, for liquid yeast you need to oxygenate the wort prior to pitching.

As long as you have fermentation activity going now, I'd let it ride and see what you get in the end.

 

[Brewer #356985]

Thanks for reply.
I pitched in two of those at about 20 C. The thing is that the activator in the bags did not work. Usually the bag swells up after a few hours but that did not happen this time.
I had 40 l wort going in to fermentation so I had no choice but pitching it in. I got new yeast that worked and now the fermentation is ongoing but slowly. Due to the fact that i am fermenting under pressure i was not able to oxygenate the wort during pitching the yeast. The OG was at 1.056.
I have made many brews but this is the first time this happens

 

[Bigbre04]

20c is high for that yeast(i would think). I generally run my lagers(apex Augustinian/munich Lager/Mexican lager) down at 14c. I also pressure ferment most lagers to avoid the off flavors from warm fermentation(14c is technically at the high end of the range for most of those yeasties).

Lagers even with big pitches and good yeast can be a little sluggish to start.

If the bag didnt puff up, i would assume the yeast was bad??? i use dry so someone else would know more then i on that.

 

[Dave Y]

If the bag didnt puff up, i would assume the yeast was bad??? i use dry so someone else would know more then i on that.

yup, that's what I was thinking.

Liquid yeast doesn't last as long and I think is a bit less robust in shipping, etc. Even if the best by date was still a few months off, you never know if that yeast got stuck over a weekend in a UPS truck during a heat wave.

You've got it moving, but like @Bigbre04 said, that temp could be a bit high. IF you can get the temp lower it may actually speed up just a bit once the yeast is in "its happy place".

Good job rescuing it.

Due to the fact that i am fermenting under pressure i was not able to oxygenate the wort during pitching the yeast

Why?
You had to bleed off the pressure to put the yeast in, right? If this happens to me; scratch that, the last time this happened to me it was a lager too and I grabbed a spare packed of dry lager yeast - it had about a year left on it, and I did a starter culture on it. Once the starter was ready I bled the pressure off, pitched the new yeast, set the pressure down to zero at first, to try and get any O2 out then raised it to 5, bled a few times, then about 8-10 to finish. It's on tap now, a Vienna lager.

 

[J A]

Pitching at 20C and then dropping over the first 12 to 24 hours to 14 or 15C isn't a bad way to do things. If you're holding that temp because your fermenting under pressure, it should still work but 17 or 18C is about as high as I would go.
You got a dead yeast pack. I wouldn't count on anything over 6 weeks old if I wanted a decent live cell count. It's the problem with liquid yeast. At the homebrew level, we don't have access to big, fresh pitches direct from the yeast farms. We have to count on whatever we can get and it's very likely to be a 4-month-old pack and/or may ship in a hot truck.
I know that some brewers swear by liquid yeast but any benefit that might convey is likely negated by the uncertainty about cell count. Dry yeast has become much more viable and acceptable and there's not much reason not to use it at the homebrew level. A brick of lager yeast is fairly cheap and it will make a lot of beer and you have very close control over cell count.

 

[Sandy Feet]

You do have to watch the dates on the liquid yeast.

 

[Donoroto]

Thanks for reply.
I pitched in two of those at about 20 C. The thing is that the activator in the bags did not work. Usually the bag swells up after a few hours but that did not happen this time.
I had 40 l wort going in to fermentation so I had no choice but pitching it in. I got new yeast that worked and now the fermentation is ongoing but slowly. Due to the fact that i am fermenting under pressure i was not able to oxygenate the wort during pitching the yeast. The OG was at 1.056.
I have made many brews but this is the first time this happens

First, don’t worry. Focus now on temperature control. It will end up fine.

2 packs is definitely an under-pitch for 40 liters. The label lists different starting gravities, and the smallest one shows 2 packs … but for 25 liters. And the number of packs increases from there.

It will never go fast, but it will go to the end and make good beer. So, be patient.

 

[Bigbre04]

I brewed my golden lager(1 of 2 batches) yesturday 11.6 OG. knocked out a little hotter then i wanted(15.7actual vs 14SP), but got it cooled overnight. Knocked out 76gals. pitched 250g of apex augustin lager yeast. this morning it had dropped from 11.6 to 11.3p. this tracks exactly on target with my previous batches.

i expect roughly .3-.4 drop overnight on a fresh lager pitch.

I am brewing a second batch today. i will set the spunding valve to 10psi before i leave today.

just for reference!

 

[Minbari]

I didn't see anyone ask, i will ask. What temp did you mash at?