[homoeccentricus]

do you let the pack swell up before you make a starter with it?  in the past I generally didn't bother.

Yes, not allowing a smack pack to swell is throwing away its strength.  When used properly, pitching yeast from a smack pack is like pitching a first-level starter at high krausen.

I must be something terribly wrong here. Last couple of times I tried to smack a pack, the pack either burst open or the nutrient packet was not broken 

[HoosierBrew]

I've used 1098 vs 007 side by side. Wyeast can't hold a candle to WLP007. It's not even close. Almost 10 points in difference in attenuation in favor of White Labs.

Wow, I don't know. I make an Arrogant Bastard-ish beer using 1098 and it eats sugars like crazy in that grist. I came out slightly lower than intended the last couple times.

EDIT - I've never used 007, so I can't compare. Just saying that I get pretty high attenuation (1.070 to 1.010 in that recipe) with 1098.

[RPIScotty]

For me that list would go something like 3787, 3522, 1968, 3522, 1272, 1272.

Sent from my iPhone using Tapatalk

[evil_morty]

man, wish I had time to try and have a good opinion about that many yeasts!

[denny]

do you let the pack swell up before you make a starter with it?  in the past I generally didn't bother.

Yes, not allowing a smack pack to swell is throwing away its strength.  When used properly, pitching yeast from a smack pack is like pitching a first-level starter at high krausen.

Are you saying that there's significant cell replication as it swells?  Either I'm misunderstanding or you're at odds with what Wyeast says.

From Greg Doss in response to a question I emailed him in 2005....

Thanks for the email.  I'm sorry to say that very little cell growth is
occurring in an activated package of yeast.  Typically there is about a
10% increase in cell density.  In any fermentation, yeast growth is
controlled by the depletion of a limiting nutrient.  In the Wyeast smack
pack, sugar is the limiting factor.  There is not enough sugar available
to provide the yeast enough energy to support a large amount of growth.
However, the nutrients that are introduced to the yeast are used for
cell membrane synthesis and nutrient uptake starting the culture's
metabolism.  By starting the culture's metabolism before pitching, the
brewer can greatly reduce lag times.  The CO2 which causes the swelling
is a by-product of this small amount of metabolism.

I hope that this helps.  If you have further questions, please ask.

Greg


Greg Doss
Microbiologist/ Brewer
Wyeast Laboratories

[ynotbrusum]

For the Leinies Snowdrift, I would not be surprised if this was made with a lager yeast ala a Baltic Porter....

[S. cerevisiae]

I've used 1098 vs 007 side by side. Wyeast can't hold a candle to WLP007. It's not even close. Almost 10 points in difference in attenuation in favor of White Labs. I also feel WLP001>WY1056. But, it's all beer, brewing, and a matter of personal preference and taste.

You did something wrong or you are comparing apples to oranges wort compositions if the difference in attenuation was ten points.  They are the same strain of yeast. 

[S. cerevisiae]

Are you saying that there's significant cell replication as it swells?  Either I'm misunderstanding or you're at odds with what Wyeast says.

The keyword was "like."   It's the state of the cells, not the cell count to which I was referring. The nutrient in the smack pack brings the culture out of quiescence just like a first-level starter, and it is doing it in a fairly sterile environment.  The difference is that the Smack pack is carbon limiting, so there is very little replication.   If we do not smack the pack, we are pitching quiescent cells that have been living off of their glycogen and threhalose stores.  If we smack the package and allow it swell, we are in effect stepping a started culture when we pitch it.  A non-quiescent culture experiences a shorter lag time than a quiescent (sedimented) culture.

The reason why we pitch a starter at high krausen instead of waiting until it sediments is because we are attempting to shorten the lag phase.  Shortening the lag phase allows us to reduce our pitching rate because replication starts earlier. The lag phase is shortened by pitching at high krausen due to the reduced need to replenish ergosterol and unsaturated fatty acids (UFA), and because the cells have not undergone survival-related morphological changes.  With quiescent (sedimented) cells, ergosterol and UFA reserves have to be rebuilt, and the survival-related morphological changes have to be reversed before the cell can start to consume carbon from the wort.  Ergosterol and UFAs are synthesized in the respirative metabolic pathway by the pitched cells during the lag phase  Pitching at high krausen also reduces the initial O₂ load that the pitched cells place on the wort because they have to synthesize less ergosterol and UFAs.

Greg was writing about ergosterol and UFA synthesis when he wrote "cell membrane synthesis."  Ergosterol and UFAs make the cell plasma membrane more pliable, which makes it easier for nutrients to enter and waste products to exit the cell.  He was referring to completing the reversal the survival-related morphological changes when he mentioned "starting the culture's metabolism."  As an aside, due to the storage of glycogen and trehalose in addition to the thickening of the cell wall, quiescent yeast cells are denser than yeast cells that are in fighting shape.

[denny]

Thanks, Mark.  I thought that was what you were referring to, but I wanted to be certain.