[Steve Ruch]

Like many things lag time is relative. 17-20 hours is not all that long, but if you normally use a different yeast that usually starts up in 4-5 hours BRY-97's four times as long can give the nerves a little stress.

[denny]

.... The more this discussion goes around, the more I begin to wonder how much of this is just semantics.

...

Very well could be.

I get similar results with lower pitch rates and no Fermax.  Why?  Thats what I'm truly trying to understand.

I dunno. . Like everyone, we only have our experience to go on.

Fire up those Experimental Brewing dudes.

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Personally, I  chalk it up to many roads to the same destination.

I wish I could fire those guys up, but I think they're dead

[BrewBama]

I will be interested to hear about two specific things in any comparison - actual gravity readings through the course of pitch to completion (or at least measured gravity readings on comparable devices - I am thinking a Tilt or similar) and total duration of the fermentation. 

I have not recently used K-97, but intend to do so eventually and will try to remember to track the dynamics (it is so easy to do with the numerous charting software available with the newer instruments, like the Tilt).  I would expect 10 gallons of the same wort split between two 5 gallon batches, with one pitched at 23 grams - 2 packs - and one pitched with 11.5 grams.  Other variables to measure would be time to full krausen (visually, I suppose), effect of fermentation under pressure compared to airlock fermentation (if any difference), and rehydrated versus sprinkled (could be two different sprinkles based on the partial rack from BK, sprinkle, complete the rack from BK, versus just sprinkling at start or finish of racking), and aerating wort or not, to name a few.....

I’ll be happy to provide any data that I’ve collected.

IMO, waiting days for yeast to start is unacceptable. I believe that’s just too much opportunity for O2 pickup or other issues. Again, no evidence for that, but that’s my gut feeling.

That’s the reason I began researching and found the mfr recommendation. I was pitching one pack (78% of the recommendation using my example above). I live by ‘close enough is good enough’ but in my mind 95% is close. 75% isn’t.

Once I began pitching the recommended qty the problem disappeared and I was happy again. Now, I can set my clock by 14  +/- 2 hrs.

The mfr recommends 18 + grams for Denny’s example (1.066 in 6 gal). He pitched 61% of the recommendation.

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[denny]

I will be interested to hear about two specific things in any comparison - actual gravity readings through the course of pitch to completion (or at least measured gravity readings on comparable devices - I am thinking a Tilt or similar) and total duration of the fermentation. 

I have not recently used K-97, but intend to do so eventually and will try to remember to track the dynamics (it is so easy to do with the numerous charting software available with the newer instruments, like the Tilt).  I would expect 10 gallons of the same wort split between two 5 gallon batches, with one pitched at 23 grams - 2 packs - and one pitched with 11.5 grams.  Other variables to measure would be time to full krausen (visually, I suppose), effect of fermentation under pressure compared to airlock fermentation (if any difference), and rehydrated versus sprinkled (could be two different sprinkles based on the partial rack from BK, sprinkle, complete the rack from BK, versus just sprinkling at start or finish of racking), and aerating wort or not, to name a few.....

I’ll be happy to provide any data that I’ve collected.

IMO, waiting days for yeast to start is unacceptable. I believe that’s just too much opportunity for O2 pickup or other issues. Again, no evidence for that, but that’s my gut feeling.

That’s the reason I began researching and found the mfr recommendation. I was pitching one pack (78% of the recommendation using my example above). I live by ‘close enough is good enough’ but in my mind 95% is close. 75% isn’t.

Once I began pitching the recommended qty the problem disappeared and I was happy again. Now, I can set my clock by 14  +/- 2 hrs.


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So the issue for you was more paranoia (no judgment there) than beer quality?  You didn't perceive any issues but you were afraid there might be?

[BrewBama]

It was more of a consistency issue. I was all over the map with lag times, fermentation times, and attenuation. I get very consistent results now in all three.

The only issue with the beer itself was sometimes it was fully attenuated and other times it wasn’t. It wasn’t ‘bad’ beer but wasn’t what I was expecting from beer to beer. There was no consistency in similar recipes.

Edit: one other thing. If a pack a batch worked for me I would not pitch more. It just didn’t.

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[denny]

It was more of a consistency issue. I was all over the map with lag times, fermentation times, and attenuation. I get very consistent results now in all three.

The only issue with the beer itself was sometimes it was fully attenuated and other times it wasn’t. It wasn’t ‘bad’ beer but wasn’t what I was expecting from beer to beer. There was no consistency in similar recipes.

Edit: one other thing. If a pack a batch worked for me I would not pitch more. It just didn’t.

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That's the way it should be.  Study the science , try things out, do what works for you.

[ttash]

Denny, you mentioned that you pitch unrehydrated and not aerated. Is it unnecessary or not recommended to oxygenate or aerate wort when using dry yeast?

[Saccharomyces]

Unlike liquid yeast, dry yeast is a propagated in a bioreactor below the Crabtree threshold.  When yeast is propagated below the Crabtree threshold, it replicates using its respirative metabolic pathway instead of its fermentative metabolic pathway.  Not only is the respirative metabolic pathway significantly more efficient than the fermentative metabolic pathway, yielding significantly more ATP from a carbon source (sugar is carbon bound to water; hence, the classification carbohydrate), it also produces cells with fully-charged ergosterol and unsaturated fatty acid reserves (UFAs).  The reason why we aerate wort is because yeast cells shunt O₂ and a small amount of carbon to the respirative metabolic pathway for the synthesization of ergosterol and UFAs during the lag phase. Dry yeast does not need to go through this step when initially pitched; however, one does need to aerate wort when repitching yeast that was received as a dry culture.

[denny]

Denny, you mentioned that you pitch unrehydrated and not aerated. Is it unnecessary or not recommended to oxygenate or aerate wort when using dry yeast?

According to people I've spoken to at botuu Fermentis and Lallemand, it's unnecessary.   AFAIK, if you do it anyway it won't hurt.

[denny]

Unlike liquid yeast, dry yeast is a propagated in a bioreactor below the Crabtree threshold.  When yeast is propagated below the Crabtree threshold, it replicates using its respirative metabolic pathway instead of its fermentative metabolic pathway.  Not only is the respirative metabolic pathway significantly more efficient than the fermentative metabolic pathway, yielding significantly more ATP from a carbon source (sugar is carbon bound to water; hence, the classification carbohydrate), it also produces cells with fully-charged ergosterol and unsaturated fatty acid reserves (UFAs).  The reason why we aerate wort is because yeast cells shunt O₂ and a small amount of carbon to the respirative metabolic pathway for the synthesization of ergosterol and UFAs during the lag phase. Dry yeast does not need to go through this step when initially pitched; however, one does need to aerate wort when repitching yeast that was received as a dry culture.

What he said!

[ttash]

Denny, Mark, thanks guys. The collective brain trust is unequaled on this forum.🍺

[BrewBama]

One think I’ve noticed about Bry-97 is that it definitely likes it warm. Even pitching at 60*F will dramatically increase lag.

I usually set my controller to 63*F and to begin cooling at 65*F. 

Just those few degrees are remarkably different in terms of lag.


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[denny]

One think I’ve noticed about Bry-97 is that it definitely likes it warm. Even pitching at 60*F will dramatically increase lag.

I usually set my controller to 63*F and to begin cooling at 65*F. 

Just those few degrees are remarkably different in terms of lag.


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My experience in the last half dozen batches is that I have active fermentation in 16-20 hours at 63-65F, underpitched by some standards.  No rehydration.  What kind of lag are you getting?

[BrewBama]

I see 16 hrs +/- 2 hrs routinely at 63-65*F. ...with vigorous fermentation soon to follow.

At 60*F I’ve seen that jump to ~20 +/- 2 hrs. ...and sluggishness.

Granted, I am looking at a Tilt hydrometer first ‘blip’. Most Homebrewers are watching the airlock bubbles and I can imagine that when I am calling ‘the start’ there is no bubble activity until much later. I don’t watch the airlock unless I happen to go downstairs and I can’t see krauzen (stainless fermenter).

These differences and others are probably where the semantics starts creeping into our use of the term ‘lag time’.


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[denny]

I see 16 hrs +/- 2 hrs routinely at 63-65*F. ...with vigorous fermentation soon to follow.

At 60*F I’ve seen that jump to ~20 +/- 2 hrs. ...and sluggishness.

Granted, I am looking at a Tilt hydrometer first ‘blip’. Most Homebrewers are watching the airlock bubbles and I can imagine that when I am calling ‘the start’ there is no bubble activity until much later. I don’t watch the airlock unless I happen to go downstairs and I can’t see krauzen (stainless fermenter).

These differences and others are probably where the semantics starts creeping into our use of the term ‘lag time’.


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When I see positive pressure in the airlock, I open the fermenter (SS conical) to see what it looks like.  That's how I make the determinarion.