When is my yeast starter "done"

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There aren't distinct boundaries between the phases of a culture. Just an average influenced by several factors.

Definitely makes sense, seems to be the way of things. I'd venture a guess that, also as these things go, there's no rule for all yeasts, each will have its own rate and some will be ready far earlier or later than others.

Still, are there visual clues in a starter? Color change, perhaps turn it off for a few minutes and look for bubbling?

I typically start my starter the night before brewing, crash the next morning, decant and pitch that afternoon. I'm certainly off to a faster fermentation than a direct pitch or a single smack pack, but always up for "better" if there is such a thing.

 

[Bassman2003]

For me, I see it as an either/or situation. Either make a starter days before brew day, let it finish and fall out to grow new cells or make a vitality starter the night before or morning to just stimulate yeast activity before pitching. One gives you more yeast than you started with, the other kind of energizes the existing yeast but will not result in very much growth.

Overnight might not be enough time (7-12 hours) to do very much other than wake them up (depends on how fresh the pitch is). Trying to decant an active starter seems like you would inevitably throw out some yeast cells. Making the starter days ahead will give it enough time to create new cells so you end up with a larger pitch than what comes in the purchased vial.

 

[McMullan]

Definitely makes sense, seems to be the way of things. I'd venture a guess that, also as these things go, there's no rule for all yeasts, each will have its own rate and some will be ready far earlier or later than others.

Still, are there visual clues in a starter? Color change, perhaps turn it off for a few minutes and look for bubbling?

I typically start my starter the night before brewing, crash the next morning, decant and pitch that afternoon. I'm certainly off to a faster fermentation than a direct pitch or a single smack pack, but always up for "better" if there is such a thing.

I'd try leaving starters for at least 48-72 hours, as there is still going to be significant growth occuring, even when it looks like it's done, post-krausen. Then compare that with repitching freshly harvested yeast.

 

[McMullan]

Here's a healthy starter at 54 hours:

The starter appeared to be done, the cells are even flocculating, but there's clearly significant ongoing budding. I'd ignore most of what appear to be 'dead cells' staining blue here. I suspect the cell membranes become permeable to the dye (trypan blue) at a specific time in budding regardless of viability.

 

[user 246304]

This doesn't make any sense, biologically speaking. I think it was Escarpment Labs who might have suggested cooling, rather than dwindling sugar levels, promoted storage of reserve carbohydrates in brewer's yeast. It makes much more sense to allow the yeast starter to finish at warmer temperatures, before storing cool, so as to facilitate (increase the rate of) the process of storing reserve carbohydrates which support the dormant state, e.g. at cool temperatures. Cooling at high krausen is only going to shock the active yeast cells and risk high pressure building up in a sealed vessel due to residual metabolism of the remaining sugars.

Tweaking my regimen. Though this is an old post and thread. Typically I have let the stirplate go only until it was evident maximal growth was achieved, then crashed for a day or two, to secure a dense cake and decant. Am I understanding correctly the better approach is to let it ferment out completely, then crash - I think I saw McMullan, you went up to 72 hours on the stirplate before crashing?

 

[McMullan]

Tweaking my regimen. Though this is an old post and thread. Typically I have let the stirplate go only until it was evident maximal growth was achieved, then crashed for a day or two, to secure a dense cake and decant. Am I understanding correctly the better approach is to let it ferment out completely, then crash - I think I saw McMullan, you went up to 72 hours on the stirplate before crashing?

Yes, but I don’t bother with a stirplate any more. If you let them finish and adapt to a resting state naturally, they have more tolerance and likely have a shorter lag phase when pitched.

 

[HighVoltageMan!]

3 put the starter in the fridge at high Krausen, and flocculate the yeast, then decant and pitch

I have switch to this method. Allowing the starter to finish completely has no advantages and may actually harm the yeast by using up it's glycine reserves. Pitching at high krausen is the best way, but when making a 4 liter starter for a Greman Pils, I don't want the beer from the starter to change the original beer, so I put it in the frig at high krausen. The problem is that lager yeasts can be stubborn to drop and it takes 2-3 days to drop the yeast. Since doing this method my lag times at 48F with 2124 yeast are as low as 12-14 hours compared with 18-24 hours with the same size starter.

This basically the same idea behind "shakened not stirred" method. With SNS the entire starter is pitched at high krausen when the yeast are in a high metabolic state.

 

[user 246304]

Yes, but I don’t bother with a stirplate any more. If you let them finish and adapt to a resting state naturally, they have more tolerance and likely have a shorter lag phase when pitched.

Great, thanks. So I recall seeing your video, very cool one, of an oxygenation stone at the beginning, while on the stirplate. You no longer stir at all then, is that correct? Do you oxygenate or don't even bother?

 

[McMullan]

Great, thanks. So I recall seeing your video, very cool one, of an oxygenation stone at the beginning, while on the stirplate. You no longer stir at all then, is that correct? Do you oxygenate or don't even bother?

Yes, I occasionally use it to mix wort while oxygenating it with pure O2.