2+ day lag time

[barleyfreak]

This has only happened once before and I'm scratching my head to see what I did (differently) to perhaps cause it. On a 7bbl batch,

• Doughed in, at around noon, then took about 17 lbs of wl002 English Ale yeast (4th gen, 3 days old) out of walk-in
• walk-in temp averages about 34-36
• Pitched at 64 degrees through manway at about 6pm after 30 minute knockout with 8 LPM O2 flow
• SG was 15.3p

All this is SOP and I've done it with this yeast about 25 batches since we opened last summer. On every occasion except one other time, the next morning shows significant bubbling. This time nothing. Nothing 24 hours later. Nothing 36 hours later. Checked and rechecked all valves were closed. Gravity had dropped 1p, but I had to almost question if my OG was really accurate. At 36 hours, gave it a blast of O2 to rouse. Waited until that night and with still no activity, or change in SG, gave it another longer blast of O2 and pitched another 5 lbs of yeast. Finally, the next morning, 2.5 days after pitch, it was rockin'.

Can't tell yet how it is going to turn out. I have pitched almost every batch (42) at 64 degrees, letting it rise about 1 degree/day until diacetyl rest with a similar amount of yeast, and age of yeast (no cell counts). I'm scratching my head trying to figure out what was different. Same recipe in the past had no prob.

I did do an acid rinse a couple days before on the FV and let it air dry to re-passivate. But I rinsed with water again thoroughly before sanitizing/filling, though with 55 degree water rather than 120, which was the acid rinse temp. That is the only thing different I can think of.

When it happened the one time before it showed signs at the end of day 2, on gen 6 of the yeast, but I dumped it afterward being skittish and new to the pro ranks. Wondering if I need to here with this one.

Any ideas?

[Junkyard]

You said you pitched the yeast in the man way at 6 pm, is that a top manway? Do you know what temp the yeast was when you pitched it? Are you sure the fermenter was totally sealed up on day 2?

[barleyfreak]

It was the side manway, after about 40 gallons of the 64 deg wort was in. Don't know actual yeast temp, but it was in 3 one gallon wide mouth plastic jars and had been at brewhouse temp for about 6 hours. I suppose it is possible that it got too warm. It was prob 70 deg in the brewhouse by then. Maybe that 70 to 64 deg temp dropped shocked it? But it has been pretty SOP and so other yeast has had similar warm up times/temp.

Did check that everything was sealed. When rousing the first time, I closed off the blow off arm, and when releasing it, a bunch of the O2 bubbled out, so I think it was sealed well. And it was going gonzo the morning of day 3.

[Yeast]

your yeast was it a new supply or did you harvest it?
sounds like the yeast might have appeared to be alive but very low on glycogen stores which can cause a long lag phase even if you properly oxygenate. if you have a scope large vacuoles in yeast cells are a good way to look for that if you don't have the equipment to do vitality tests, viability is easy but even viable sells may be on the edge and just appear viable.

if you don't have any options and you have yeast that's low on vitality you can over pitch usually in the 1,500,000 cells per plato per mL range.

[barleyfreak]

It was harvested, 4th generation, 3 days old. Don't have microscope setup yet. Once it got goin everything -- taste, smell seemed fine. Decided to harvest again for subsequent batch -- pitched more, and increased O2 flow during knockout and the next gen is humming along. Not sure what to attribute it to, especially since the SOP has been pretty consistent and there was nothing to really standout differently with this pitch. But w/o a microscope...gotta get a microscope.

[fernholz]

Over Oxygenation?

How long was your knockout? 8lpm seems pretty high. My hypothesis is that you got a ton of O2 in solution and that put your yeast into a super long reproductive cycle working to eat up all that Oxygen. We knock out at about 1BBL / Minute and oxygenate at 1lpm and see lag times of 12 hours or less and plenty of yeast to harvest at the end of fermentation.

[barleyfreak]

knockout for the 7bbl was 30 minutes. That is faster than normal. I usually knockout in 35-40 in the winter, and 45-50 in the summer

[soia1138]

Honestly this is one of those things that would make me curious and pay attention to subsequent brews, but so far seems like a one time oddity in your normal SOP. Trying to come to some kind of conclusion is just jumping to conclusions, meaning I wouldn't sweat it. Take note, be on the lookout down the road and if you see it again, maybe then some pieces will start to come together. Too many variables to even stress on it in my opinion. It's like taking your car to a garage after it has made an odd noise once.

[barleyfreak]

Yeah I have to agree. It's an outlier for me at this point. Posted originally to see if anyone else had run into such an anomalous behavior w/o deviating from SOP and might offer an explanation. Like I said, I'm still using that yeast and the next gen after is performing like a champ. Will take good notes, stay consistent, and see if I can connect any dots if it happens again.

cheers,

[Yeast]

How long was your knockout? 8lpm seems pretty high. My hypothesis is that you got a ton of O2 in solution and that put your yeast into a super long reproductive cycle working to eat up all that Oxygen. We knock out at about 1BBL / Minute and oxygenate at 1lpm and see lag times of 12 hours or less and plenty of yeast to harvest at the end of fermentation.

the yeast eat the oxygen up very quickly within minutes to less than a few hours.

a good SOP is don't assume your yeast is going to perform the same as it always has because of a macroscopic inspection.