yeast pitching temperature

[Kev888]

Just to add a less scientific observation, IMO the use of packs marketed as suitable for (say) 5gallons of typical wort leads people to incorrectly think pitching rates are related just to volume, perhaps with something additional happening around 1.050-1.060.

But in reality pitching rates are related to both volume 'and' gravity - typically referred to as the number of viable cells wanted per ml of wort per degree plato. So the number of cells in a sachet can become insufficient due to increasing gravity, just as they can with increasing volume.

Some people feel things are already being stretched if using a sachet towards the upper end of manufacturer's claims, especially if pitching without rehydration (as fewer cells make it through). If there is no long lag or difficulty reaching FG then you probably don't have a problem as such, but there may still be differences in the quality of results - with esters for example.

[McMullan]

When I'm fermenting at the cool end for ales (around 17C), I used to cool the wort to that temperature and pitch there. I think that followed advice in the White/Zainasheff book, in terms of pitching lower (if at all) and raising, rather than the other way around. Nowadays, I tend to chill to around 20C, and set the fridge for 17, if that's where I'm heading, and therefore no detrimental effect on ester profile. That's based on the theory that there isn't much growth going on in those first few hours it takes to get down to 17; I believe the yeast is just doing its stuff to get ready, at that point, soaking up nutrients. I imagine it does that quicker at warmer temperatures, so the lag may be reduced. Also, my starter will have been grown warmer than that, and is on its way down at that point anyway, so I let it join the wort around 20C, and set the control to 17. Seems to work for me, but if any white coat folk can cut through my conjecture, I'm happy to learn.

Perfectly acceptable strategy. I've had to adopt it myself occasionally, when my wort temperature readings have turned out to be higher than measured by the kettle thermometer. The initial lag phase is typically quite short, about 2 hours. This is where stored glycogen is metabolised to fuel lipid synthesis, for cell membranes. The cells increase in size and start budding within 2-3 hours of pitching. We don't necessarily notice much going at this stage, because the cells/ml are actually quite low at this point. Glucose metabolism has started already. Within several hours it should be clear there is a fermentation, with maximum budding and gravity dropping. Ideally, the target fermentation temperature is reached by this time. So there is plenty of time to bring the temperature down, even by several degrees. Obviously, it's kinder on the yeast to have them at the same temperature as the wort at pitching. Not doing so can extend the lag phase by several hours.

[MTW]

When I'm fermenting at the cool end for ales (around 17C), I used to cool the wort to that temperature and pitch there. I think that followed advice in the White/Zainasheff book, in terms of pitching lower (if at all) and raising, rather than the other way around. Nowadays, I tend to chill to around 20C, and set the fridge for 17, if that's where I'm heading, and therefore no detrimental effect on ester profile. That's based on the theory that there isn't much growth going on in those first few hours it takes to get down to 17; I believe the yeast is just doing its stuff to get ready, at that point, soaking up nutrients. I imagine it does that quicker at warmer temperatures, so the lag may be reduced. Also, my starter will have been grown warmer than that, and is on its way down at that point anyway, so I let it join the wort around 20C, and set the control to 17. Seems to work for me, but if any white coat folk can cut through my conjecture, I'm happy to learn.

Perfectly acceptable strategy. I've had to adopt it myself occasionally, when my wort temperature readings have turned out to be higher than measured by the kettle thermometer. The initial lag phase is typically quite short, about 2 hours. This is where stored glycogen is metabolised to fuel lipid synthesis, for cell membranes. The cells increase in size and start budding within 2-3 hours of pitching. We don't necessarily notice much going at this stage, because the cells/ml are actually quite low at this point. Glucose metabolism has started already. Within several hours it should be clear there is a fermentation, with maximum budding and gravity dropping. Ideally, the target fermentation temperature is reached by this time. So there is plenty of time to bring the temperature down, even by several degrees. Obviously, it's kinder on the yeast to have them at the same temperature as the wort at pitching. Not doing so can extend the lag phase by several hours.

Thanks for the explanation; good to know.

[Kingfisher4]

Thanks all, very helpful responses as usual.

[Kingfisher4]

Re-reading this thread after my first year of brewing and 20 AG brews now makes me appreciate the time and wisdom shared so generously on this forum even more.
Thank you all again.
What a great hobby this is!

[orlando]

Re-reading this thread after my first year of brewing and 20 AG brews now makes me appreciate the time and wisdom shared so generously on this forum even more.
Thank you all again.
What a great hobby this is!

[WalesAles]

What a great hobby this is!

Yes, Indeed!
Even though I still do Kits and BIAB, I still read mostly everything on JBK and love all the Feedback!
Got to go now, squeeze my dry hop bag, take it out of the FV, bottling Monday.

WA

Sent without Taptertork.