[dmtaylor]

The following thread prompted a eureka moment for me just now: Are we all in fact overpitching with all of our dry yeasts?

https://www.homebrewersassociation.org/forum/index.php?topic=27436.msg357686#msg357686

As many of us already know, dry yeasts are super reliable and shelf stable.  Even a 2-year old (or older!) packet of dry yeast can simply be sprinkled on top of 5 gallons of wort and immediately get to work in a matter of 12-16 hours, and typically will finish its job as quickly if not quicker than a huge starter of liquid yeast.

So..... what the hell is going on?  What's so special about dry yeast?

And then there's the continuing complaints over "my Belgian or hefeweizen is too clean".  I wonder: Is it just too darn easy for us to all overpitch when we use dry yeast?  These yeasts basically require some stress in order to give us the best flavors.  But if we always pitch 11 grams into 5 gallons, isn't that way too much to stress out these yeasts??

I wonder if maybe the dry yeasts are really all TOO good, TOO healthy, and there's TOO much placed into each packet, such that maybe, just maybe, we should really only be pitching 1/4 to 1/2 of a dry yeast packet into any given batch of 5-6 gallons of wort.  Thus we can expect all those esters and phenols, as applicable, plus save some of the yeast packet for next time, as well as save some money on yeast, and all without having to ever make any yeast starters.

Thoughts?  Are dry yeasts just TOO good to pitch the whole pack???

These questions might cause some folks to become excited.  I'm just thinking out loud.  But I do think there might be something to all this, especially for Belgians, German hefes, and maybe even the S-04 and Notty but more experiments would be needed to confirm and I don't know if anyone would dare pitch just 1/4 or 1/2 pack of S-04.  That one I might worry about.  But it might also be interesting to know if anyone has ever tried this and what the results were.

[brewinhard]

I hear what you are saying. And with those thoughts in mind, I have always pushed the higher gravity batches to only pitch 1 packet of dry yeast with no issues whatsoever. As a small data point, I have used 1 packet of US-O5 (rehydrated) in a 1.082 OG wort and had it ferment down to 1.011 with no problems or off-flavors whatsoever. I will really only pitch 2 packets if I go above 1.100.

Lately, I have been into repitching liquid yeasts for 4-6 generations with great results and haven't even touched a dry yeast packet in months.

[HoosierBrew]

It's definitely worth some experimentation. Who knows, maybe Belle Saison (for example) gets more interesting on half a pack ?

[denny]

Well, here we go with another homebrew myth....I don't believe pitching less yeast necessarily equates to more flavor/character.  My experience has been in line with what Dr. Clayton Cone of Lallemand has said.  He claims that the same enzyme, acetyl co-A, is responsible for both cell growth and ester production. He says that when it's doing one it won't be doing the other.  So, by pitching less yeast, you get more cell growth and fewer (not more) esters.  This has been my experience in general.  I realize others have had other experiences.

[HoosierBrew]

FWIW, I don't make a habit of underpitching, Denny - I pitch plenty. Except in the case of hefeweizen where it seems (to me) that 3068 gets more estery on an underpitch.

[dmtaylor]

What if I want more phenols, not esters?

[a10t2]

What if I want more phenols, not esters?

Ferulic acid rest?

[dmtaylor]

What if I want more phenols, not esters?

Ferulic acid rest?

Possibly, but I have my doubts.  More experiments are needed.  Brulosopher? 

[mabrungard]

I'm curious about this effect. I have to admit that I'm inclined to believe that additional yeast generations and growth will lead to more esters. Another school of thought is that the rate of growth is also a factor in ester and fusel production. This clearly is suited to a Brulosophy exbeeriment.

[narvin]

What if I want more phenols, not esters?

Ferment colder?  It's not a hard and fast rule, but for yeasts that can produce esters and phenols (Belgian and German wheat) colder fermentation often expresses the latter.

[erockrph]

What if I want more phenols, not esters?

Ferment colder?  It's not a hard and fast rule, but for yeasts that can produce esters and phenols (Belgian and German wheat) colder fermentation often expresses the latter.

I was under the impression that fermenting cooler didn't necessarily increase phenol production. Rather, it suppressed ester production, and thereby swinging the phenol/ester balance towards the phenolics. Of course, that could just be another homebrew myth.

[HoosierBrew]

What if I want more phenols, not esters?

Ferment colder?  It's not a hard and fast rule, but for yeasts that can produce esters and phenols (Belgian and German wheat) colder fermentation often expresses the latter.

+1.  I find 3068, for example, to give more clove at cooler temps (63-64F), more banana at warmer temps (66-68F).

[Todd H.]

I'm curious about this effect. I have to admit that I'm inclined to believe that additional yeast generations and growth will lead to more esters. Another school of thought is that the rate of growth is also a factor in ester and fusel production. This clearly is suited to a Brulosophy exbeeriment.

I did the math on this once...
Let's say you pitch a 1L starter into 20L of wort.  That allows for (optimally) 4-5 doublings.  If you "underpitch" by half, that's one additional doubling.  Let's say 50 billion cells going to 100 billion cells.  After that 100 billion doubles 4 times, it will be 1.6 trillion cells.  That initial one extra doubling is like a drop in the bucket when you add up the total number of individual cell divisions (an additional 3.3%... 50b to 100b to 200b to 400b to 800b to 1.6b means an extra 50b/1.5t cell divisions).  I've always found it hard to believe that that additional generation of cells had any impact on flavor, unless there is some sort of quorum sensing thing going on and the culture as a whole senses that they are low in numbers and for some reason start secreting esters because of it.  Don't know why that would happen.  In addition, when I did look this up in the literature awhile ago (specifically for lager yeasts) you can find ample papers suggesting that overpitching leads to problems, not "underpitching".  Of course, being science, you can find older papers saying the opposite.  Not necessarily with the same strains, so maybe it is a strain-to-strain thing?
That's my former yeast biologist self thinking.  I could be wrong.  I'm 20 years out of the field.

[zwiller]

Well, here we go with another homebrew myth....I don't believe pitching less yeast necessarily equates to more flavor/character. 

+1;  My personal take on this is that for some reason (maybe it is known why) the manufacturers of dry yeast use more of the neutral strains.  I used WB06 on a hefe and it is a great yeast, but ain't no 3068 and very much doubt any manipulation will change the results. 

Curious if many would agree "liquid is better than dry" is now a myth as well?  Same strains of course. 

[dmtaylor]

Curious if many would agree "liquid is better than dry" is now a myth as well?  Same strains of course.

If true, it's only temporary.  More excellent dry yeasts are coming out all the time.  One example: Take a look at Belle Saison.  That's a super awesome yeast, which nobody should deny (but probably will just to be contrarian if nothing else).  I must confess I have not tried the weizen strains yet but intend to, maybe next year.  And I'll be sure to underpitch, like only 1/16 of a packet for a 1.7-gallon batch.