When is my yeast starter "done"

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letsallgoforasoda

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I have had a 1L white labs sanfranciso lager starter on a stir plate for approaching 24 hours. I'm not brewing today, I am making the starter so I can store it and use it on Monday.
Since I'm not going to pitch it today how long do I want to let it go before storing?
I have dug around a bit and run into a lot of conflicting answers if anybody has any advice or can point me to an old post that can explain I'd appreciate it.
 

day_trippr

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fwiw, I rarely run a starter beyond 24 hours - if I do it's because something distracted me :)
Assuming a healthy cell count to start, by that time not only is the "food" all gone but the yeast will already be heading for survival mode...

Cheers!
 

Bassman2003

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There are two schools of thought or approaches:

1) Pitch the starter at high kreusen. Basically, when it is at its most active state, get it into the fermenter so they can go to town.

2) Let the starter finish out completely (clear), cold crash it, store in the fridge until brew day, decant or siphon away the starter wort and pitch.
 
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letsallgoforasoda

letsallgoforasoda

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There are two schools of thought or approaches:

1) Pitch the starter at high kreusen. Basically, when it is at its most active state, get it into the fermenter so they can go to town.

2) Let the starter finish out completely (clear), cold crash it, store in the fridge until brew day, decant or siphon away the starter wort and pitch.

This is where my novice brewing brain gets confused. Will it clear up and have the yeast fluctuate and fall if its on a stir plate?
 
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letsallgoforasoda

letsallgoforasoda

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fwiw, I rarely run a starter beyond 24 hours - if I do it's because something distracted me :)
Assuming a healthy cell count to start, by that time not only is the "food" all gone but the yeast will already be heading for survival mode...

Cheers!

Would it be safe to cold crash it at that point or are you just going <24 when you pitch the whole starter
 

TheMadKing

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There are two schools of thought or approaches:

1) Pitch the starter at high kreusen. Basically, when it is at its most active state, get it into the fermenter so they can go to town.

2) Let the starter finish out completely (clear), cold crash it, store in the fridge until brew day, decant or siphon away the starter wort and pitch.

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

day_trippr

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Would it be safe to cold crash it at that point or are you just going <24 when you pitch the whole starter

I always get my yeast pitch built up with enough time to crash for a couple of days. Then on the brew day morning I'll decant and let the rest warm up to pitching temperature while I brew the batch.

I've never pitched a full flask. Have you ever tasted spent starter beer? Ugh...

Cheers!
 
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letsallgoforasoda

letsallgoforasoda

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I always get my yeast pitch built up with enough time to crash for a couple of days. Then on the brew day morning I'll decant and let the rest warm up to pitching temperature while I brew the batch.

I've never pitched a full flask. Have you ever tasted spent starter beer? Ugh...

Cheers!

I have it was gross thats why I am trying to make a starter and decant it this time hahah.


I think it's ready for the fridge thanks for the input
 

Bassman2003

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I do not use a stir plate but the usual time for a starter to finish and drop out will be 18-36 hours. You can know when it is "finished" when the wort is clear if left undisturbed. If the stir plate is agitating the wort would probably not clear. So maybe just go by timing.

If you chill at high kreusen, just make sure you give it enough time in the fridge as it will take longer to get all of the yeast settled and out of the wort you are about to toss. You do not want to throw out your workers!
 

The M

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There are two schools of thought or approaches:

1) Pitch the starter at high kreusen. Basically, when it is at its most active state, get it into the fermenter so they can go to town.

2) Let the starter finish out completely (clear), cold crash it, store in the fridge until brew day, decant or siphon away the starter wort and pitch.

The above is how I do it. If I don't have extra day or two before brew day I pitch the whole starter into the fermenter. If I'm able to whip up a starter couple days before a brew day I'll cold crash it and decant the starter before pitching to the FV. In my opinion both options are equally good. Haven't ever noticed any difference in final product. Just pitch enough yeast cells (using pitch rate calculator), aerate the wort, control the fermentation temp and you should be fine
 

marc1

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Escarpment Labs has been doing webinars on yeast and beer. They then put them on YouTube. Their recommendations for starters are at are at ~1:03:50:

Basically spin it until it floccs, or up to 36h, then let it sit on the counter 2 days, then cold crash it and decant.
 

Deadalus

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My last five brews were all with different liquid yeasts in the package that I made starts for. Four were ales, one was a lager. Two were out of date by under a year. I would say while there was activity in the starters at 24 hours, I like to see a little bit of foam happening and they weren't showing that until 36 hours. The ales were only temperature controlled to 69F, I left the lager in the sixties at basement temp. Tilt data showed quick starts (<12 hours) on all five and that's conservatively stated. (I haven't downloaded the data for fine scrutiny yet.) I do use a stir plate and I oxygenate my wort but I haven't been pitching any yeast nutrient. I've pitched at 24 hours in the past and can't recall any specific difficulties but if the yeast isn't too fresh, which can be hit or miss, I'm a little reluctant to use 24 hours as a minimum. I held off pitching one of the five for about 4-8 hours to give the yeast a little extra time. I'm personally going to plan on a target of 36 hours at the minimum. If you are planning to cold crash and decant, I'd say add in at least another 24 hours.
 

BAF

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I leave them on the stir plate until the krausen drops, then cold crash in the refrigerator and decant.

Hard no on pitching the spent starter wort for me. I'll hold my wort overnight to let the starter cold crash so I can decant it before I pitch the whole starter.
 

Gusso

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I been using the SNS (shaken not stirred) method when using liquid yeast. So simple. Stir plate? You don't need no stinking stir plate!
 

smata67

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You don't want to leave the starter having done its job of fermenting out to chance. Best to monitor it to completion and that is very simple to do. Get yourself a $20 refractometer. I make my starters with 100g of DME per liter, which should give an OG of about 1.040 or so. The refractometer will read this accurately. Pitch and stir, then monitor every so often, 6 or 12 hour intervals. You will see the gravity begin to decline at some point (sometimes overnight, but I have had starters not begin to drop 36 hours after pitching old yeast) and eventually end somewhere between 1.023-1.030 (Brix of 6-8). When you measure a few times at the same lower value, it is done. Once alcohol is being produced, the refractometer is no longer accurate, but it does a great job of monitoring the changing gravity which is all you need it to do to monitor the starter.
 

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3 put the starter in the fridge at high Krausen, and flocculate the yeast, then decant and pitch
I tend to do #2 because it's easy, and will try #3 - makes intuitive sense. But on a stir plate... how do you ID high Krausen? Appearance-wise I can't really tell a difference during the process, it's just a tan colored hazy thing spinning around (outside of , say, 1968 which does eventually look like cottage cheese). I tend to make starters the night before, so perhaps it's obvious but just happening while I'm asleep and so I don't notice.
 

McMullan

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Yeast going to sleep while they are full and happy rather than having already gone through anaerobic fermentation and depleting some of their reserves.
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.
 

Deadalus

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I tend to do #2 because it's easy, and will try #3 - makes intuitive sense. But on a stir plate... how do you ID high Krausen? Appearance-wise I can't really tell a difference during the process, it's just a tan colored hazy thing spinning around (outside of , say, 1968 which does eventually look like cottage cheese). I tend to make starters the night before, so perhaps it's obvious but just happening while I'm asleep and so I don't notice.
I can answer you stir plate question but let me state my starter conditions somewhat. Room temperature in my home is 69F. That's the thermostat value in the winter. (We have a woodstove too.) The basement is lower than that. In the summer just window units. The basement rarely gets hotter than 69F. The basement is where I keep my stir plate. Recently I added temperature control but have it set to ~69F.

I don't usually see foam until about 24 hours and I don't consider that high krausen. The starter wort will begin to lighten up as if you were adding milk to black tea as you increase yeast numbers. I'll turn off the stir plate for a few minutes and see if there are any bubbles/foam forming. You will also start to generate a thin layer of yeast sediment. Sometimes I will get really thick krausening, I've had it spill out some particularly if I don't leave enough headspace when trying to get a full 2000ml. I've been aiming for 1800 for this reason since I broke my 3000ml flask. If you are actually temperature controlling at 72F, the process is likely to go faster but as I mentioned earlier what I would consider high krausen is occurring more towards 24-36 hours under my conditions.

For ale yeasts under my conditions, in the past they were 69 and under pretty much all the time or at 69F in the last few. I could be mistaken about the processes the yeast are undergoing, but I'm just adding liquid yeast to a small volume of wort made from DME. That's a ~2 liter extract brew. And some people don't make starters and pitch a liquid yeast pack into 5 gallons. It's certainly not a great beer as it has no specialty malts or hops but it's just a small amount of brewed base extract. For lager yeast, yeah well outside their range but about the middle or lower for ale yeasts so I can see wanting to decant for lagers.

Not sure how I navigated into this thread and reopened it when I responded as I was thinking it was a recent thread!

And since you mentioned cottage cheese, I happened to have videoed a short clip to show the cottage cheese effect in WLP02. Not sure if that is the same strain as 1968.*

* It'll show if you download it but I can't seem to make it show when it plays. It's an .mp4 file.
 

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TheMadKing

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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.

From white labs

What's happening in the fermentor?
  • Early fermentation (Lag Phase) - Yeast uses all the dissolved oxygen; there is no/little detectable uptake in glucose
  • 8-16 hours - First sign of active fermentation
  • 24 hours (Exponential Phase) - budding yeast cells observed, the temperature, if uncontrolled rises due to heat generated by the fermentation
  • 24-48 hours (Stationary Phase) - the rate of yeast growth and carbohydrate assimilation reaches a maximum
  • Post 48 hours (Death Phase) - The pH falls to a minimum of 3.8 - 4.4 before rising slightly towards the end of fermentation

By cooling in the stationary phase (approximately high krausen) you reduce the dead cell population, maximize cell count, and have yeast cells that have not been exposed to alcohol.

Unless you have sanitary air or oxygen flowing into your yeast starter, a stir plate is not sufficient to ensure adequate oxygen is present to eliminate anaerobic fermentation. By allowing a started to "finish" you are effectively poisoning your yeast and making them work until all available food is consumed and they have no choice but to go dormant.

At the end of the day it doesn't matter much either way. both ways make beer and its semantics and I really don't care - the guy just asked me a question and I answered my reason
 

McMullan

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From white labs

What's happening in the fermentor?
  • Early fermentation (Lag Phase) - Yeast uses all the dissolved oxygen; there is no/little detectable uptake in glucose
  • 8-16 hours - First sign of active fermentation
  • 24 hours (Exponential Phase) - budding yeast cells observed, the temperature, if uncontrolled rises due to heat generated by the fermentation
  • 24-48 hours (Stationary Phase) - the rate of yeast growth and carbohydrate assimilation reaches a maximum
  • Post 48 hours (Death Phase) - The pH falls to a minimum of 3.8 - 4.4 before rising slightly towards the end of fermentation

By cooling in the stationary phase (approximately high krausen) you reduce the dead cell population, maximize cell count, and have yeast cells that have not been exposed to alcohol.

Unless you have sanitary air or oxygen flowing into your yeast starter, a stir plate is not sufficient to ensure adequate oxygen is present to eliminate anaerobic fermentation. By allowing a started to "finish" you are effectively poisoning your yeast and making them work until all available food is consumed and they have no choice but to go dormant.

At the end of the day it doesn't matter much either way. both ways make beer and its semantics and I really don't care - the guy just asked me a question and I answered my reason
There aren't distinct boundaries between the phases of a culture. Just an average influenced by several factors. Nor would I say 'stationary phase' coincides with high krausen. It's more post high krausen, when enough cell division carries on to cancel out a low death rate and the population actually continues to grow, albeit at a lower rate. Why it's a good idea to allow a starter to finish, to maximise the cell count. And, again, it promotes remodelling of behaviour resulting in accumulation of storage carbohydrates to survive the most common natural state, dormancy. Even at room temperature the death rate is very low for at least a few days post stationary phase. The common practice involving harvesting yeast after fermentation has finished then repitching doesn't support the idea letting the yeast finish poisons them. That totally makes no sense. But if what you do works for you, you should carry on doing it.
 

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Is there any harm or benefit to cold crashing (37 degrees) after the starter finishes? I usually do it to aid in decanting it, but i could easily leave it a little while to clear up, though it won’t clear up quite as well.
 

MHBT

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Is there any harm or benefit to cold crashing (37 degrees) after the starter finishes? I usually do it to aid in decanting it, but i could easily leave it a little while to clear up, though it won’t clear up quite as well.
I tried both methods full wort pitch and decanted, i find full wort to be superior and less of a pain in the keester but to answer your question no it won’t harm your yeast, i just dont see a point in chilling and decanting unless you are stepping starter up
 

McMullan

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Is there any harm or benefit to cold crashing (37 degrees) after the starter finishes? I usually do it to aid in decanting it, but i could easily leave it a little while to clear up, though it won’t clear up quite as well.
When a starter finishes most of the yeast cells flocculate. If not, think about switching to a different strain. Cooling helps drop out the rest, mainly small immature cells. To decant or not is a personal choice, but it's good practice to decant rather than risk introducing unbalancing character or off flavours from the spent starter wort.
 

Spivey24

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When a starter finishes most of the yeast cells flocculate. If not, think about switching to a different strain. Cooling helps drop out the rest, mainly small immature cells. To decant or not is a personal choice, but it's good practice to decant rather than risk introducing unbalancing character or off flavours from the spent starter wort.

I will always decant - not dumping that starter crap in my wort. But it sounds like you are saying that there is little value in cold crashing. Just let them flocculate, and anything left in suspension is not worth keeping and can go down the drain? That makes it a hair simpler and all for that!
 

McMullan

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Cold crashing helps get the immature cells remaining in suspension to flocculate. I wouldn't wait for the spent wort to clear, though. It's going contain solids from the malt and maybe some haze proteins, too, not just yeast. But, by this time, >99% of the yeast cells have flocculated.
 

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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.
 

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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

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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

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Here's a healthy starter at 54 hours:
54h.jpg

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.
 
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