Slow Start with Yeast Slurry

[brewNYC]

I am experiencing a slow start (48hrs) with wyeast 1762 slurry Does anyone know why?

The slurry is from a 1 gallon batch brewed with 1/2 pack of Wyeast 1762. The 1 gallon batch's wort was aerated by shaking, had an OG of 1.060 and was pitched at 65 degrees. It started fermentation within 2 hours. I let it ferment at 65 degrees for 1 week, the raised the temp to 75 for conditioning for 1 week.

After 2 weeks, I bottled the 1 gallon batch and pitched the slurry directly into a 2 gallon batch of Belgian quad. The OG was 1.100. The wort was aerated for 60 seconds with pure o2, and the pitching temp was 65 degrees.

Since I essentially used my 1 gallon batch as a big starter, I expected the 2 gallon Belgian quad to take off quickly, as the 1 gallon batch had. As I mentioned above though, it actually took almost 48 hours! What do you think caused this?

I am ruling out aeration, since I poured the wort into the carboy and used o2.

I am ruling out temperature, since I pitched the quad at the same temperature as the 1 gallon batch, which started quickly.

I am ruling out under-pitching, since I used the entire cake from a 1-gallon batch.

What's left? The only variable I can think of is that the 1 gallon batch was pitched from a smack pack, so it was active already, whereas the 2 gallon batch was pitched from inactive slurry. I thought this might make a little difference, but not so much!

I suppose the high OG could also be a factor, but I am fairly certain I did not under-pitch!

 

[Pappers_]

Was the yeast you pitched in the second batch at room temperature? You said the wort was 65F, but i'm wondering if you put the yeast in the fridge and forgot to let it warm up?

 

[brewNYC]

The yeast was at room temperature- probably 75 degrees. I suppose that means it was cooled by about 10 degrees when I pitched into my 65 degree wort. Is this enough to shock the yeast?

 

[HausBrauerei_Harvey]

it's the slurry needs time to wake up, I just experienced this yesterday as well! I almost always make starters as i'm using slurry thats 1-3 months old and even though I use the correct volume of slurry given it's age and the beer OG i'm pitching into I give it a 500ml starter to 'get it going' or i'm just building up from a new vial/smack pack. With these methods I routinely have a batch rocking and at high krausen 4-8 hours after pitching.

This weekend I was using a WY3787 slurry that had only been refrigerated for 2 weeks after kegging the last beer, so I figured it was fresh enough to not need a 'wake up' starter. I pitched as normal and was alarmed to see 24 hours after pitching, just nothing! Luckily late last night ~36 hours after pitching the batch is at high krausen, but that interim time was not a good feeling for me. Lesson learned for me at least, always wake up the slurry to get it ready to rock.

 

[eric19312]

I suspect the pure O2 is the difference. I've noticed some tendency to see longer lag and growth phases when pitching with pure O2 vs just splashing. We don't tend to see visible yeast activity until after the oxygen is depleted during the growth phase kicking off the fermentation phase.

 

[brewNYC]

Ok, so I either started with sleepy yeast, or I had a long growth phase.

I suppose this begs the question- is a long lag time a bad thing? I suppose I could speed things up by making a starter next time, but is there any reason to bother, if I have more than enough cells in my slurry already?

 

[RM-MN]

Ok, so I either started with sleepy yeast, or I had a long growth phase.

I suppose this begs the question- is a long lag time a bad thing? I suppose I could speed things up by making a starter next time, but is there any reason to bother, if I have more than enough cells in my slurry already?

The usual rule of thumb is that you use 1/4 of the yeast cake from a 5 gallon batch to make the next 5 gallon batch. Your yeast slurry/cake was from a 1 gallon batch or 1/5 of the yeast cake of a 5 gallon batch. That should take a little longer for the yeast to build up to the amount wanted for the new batch. Until they use up the oxygen that you added they are reproducing. Once that oxygen is depleted you should see plenty of activity. I don't think your lag time is bad at all.