When to take your starter off the stir plate?

[Ozarks Mountain Brewery]

I'm betting any yeast manufacturer would answer your question better than us, most are very nice people

 

[Finn B]

I'm betting any yeast manufacturer would answer your question better than us, most are very nice people

I've been in touch with Imperial, and yes, they seem great people. That was about something else, but I've asked them about this, too, and I'm still hoping for an answer. It's been a few days, but I guess they've got other things to do besides answering questions from me.

 

[Mase]

... but I've asked them about this, too, and I'm still hoping for an answer. It's been a few days, but I guess they've got other things to do besides answering questions from me.

Well they are responsible for billions upon billions of lives... no matter how relatively small they are.

 

[Finn B]

I think your search for answers and your quest for better beer is admirable. Some of the best advice I heard was never take advice from someone unless you taste their beer or if they are known to a great brewer (I guess that includes my advice).

In the past I did quite a bit research on yeast and to find the answer to one question required me to go to multiple sources, most often I found the answer in some obscure white paper I found after hours of looking. I rarely found real specific information on forums, but I did find leads. People on forums may mean well, but often give misinformed answers that mislead or discount your idea.

You may find an answer somewhere, but measuring an outcome or significant improvement in the beer may prove frustrating. However, often great beer comes from an accumulation of small changes. If one of the changes were removed it would make little difference, but the sum of all the improvements/changes makes a world of difference.

I am a believer in yeast being the key to great beer, any improvement is usually worth the effort. I wish you luck. But it may be that Palmer is blowing smoke up people’s asses or he’s on to something. Who knows? Time will tell.

I'm not sure John smokes? Anyway, he's not the yeast expert, he's probably got this from Chris White, or at least he has ok'd it. (He's on the acknowledgements list in HtBr.). But I've heard this in a beersmith podcast as well from guys from Imperial Yeast - and they're yeast experts. Link to the pod in my first post.

 

[Mallonee's Malt]

So. Did this thread die? Did it move someplace else?

I for one adore the question. It's just the kind of question I like to ask (and drive people crazy with). I want to know a best practice, but I also want to know why beyond "it's always worked".

I've been using the practice of keeping yeast on the spinner for two or three days. The idea that all the sugar is used up (and also the need for oxygen?) in 12 hours is surprising to me. So yeah, the life cycle of a STARTER yeast is of interest.

And after the stir plate is stopped should it stay at the elevated temperature (I spin at 82F)? What triggers the reserves to build up? Do those reserves matter if there are more propagation stages (I like brewing 1.07 - 1.10 beer so I need a lot)?

Based on this information I'm taking way too long to get to pitchable amounts.

 

[HighVoltageMan!]

The general rule is to remove the yeast starter off the stir plate before the starter hits terminal gravity. I found the best conditions being that the starter was either pitched at full krausen or better yet, near the end of full krausen or to crash cool it under the same conditions. Leaving the yeast on the stir plate after the starter has reach terminal gravity is detrimental to the health of the yeast because it exposes it to oxygen with no "food". This causes the yeast to burn through it's nutrient reserves and weakens the yeast.

So a good rule is to pitch at high krausen or crash cool during high krausen if the yeast is not going to be used immediately (this works best for lagers). You will see shorter lag times, a more vigorous fermentation and better beer. It's better to pitch a smaller amount of healthy yeast than to pitch a lot of weak yeast.

 

[Donoroto]

Using different words: I want my yeasties to be at their peak, all revved up, when I pitch them. Letting them go until they start to starve and go dormant seems too late. I let them go for around 24 hours, I add no heat but the stir plate’s mechanicals bring it into the 80s.

 

[Mallonee's Malt]

Well, I definitely want to decant. I don't want to do all the work to make a 1.100 wort just to throw in 3l of unflavored beer even if it is at high krausen.

I guess the revelation for me is how fast those yeast start to starve. And by relation - when do you refrigerate to drop out the yeast in preparation for a decant.

My heat setup isn't very sophisticated. It's just a styrofoam steak shipping box on it's side with an incandescent light bulb in a coffee cup controlled by an inkbird.

 

[HighVoltageMan!]

My heat setup isn't very sophisticated. It's just a styrofoam steak shipping box on it's side with an incandescent light bulb in a coffee cup controlled by an inkbird.

There is no need to heat the yeast during propagation unless you are very low, 64F or lower is too low for most yeast. 68F (20C) is about the perfect temperature to propagate both ale and lager yeast, which nicely corresponds to room temperature for most conditions. Elevating the temperature speeds everything up, including the yeast's metabolism. This means the yeast propagate faster and degrade faster in the presence of oxygen.

When you see the yeast at near the end of high krausen in the starter, you can refrigerate it, this will prevent the starter from hitting terminal gravity. It's good to leave a little food for the yeast during the chilling phase of the starter. Most yeasts will flocculate (drop out) within 48-72 hours so it can be decanted prior to pitching. Try to make your starter as close as you can to brewing day for a better yeast health and fermentation. Fresher yeast makes better beer.

 

[Donoroto]

Well, I definitely want to decant. I don't want to do all the work to make a 1.100 wort just to throw in 3l of unflavored beer even if it is at high krausen.

Oh, it’s not unflavored. But you probably won’t like the flavor it has.

 

[Brew Cat]

I agree
pitch at high krausen (which is as the Krausen starts to collapse)
no need to decant since there is still yeast in the liquid portion
don't chill it
time your starter and brewing
if your going to used cold settled yeast just save it from a previous brew

 

[Mallonee's Malt]

Thanks for all the replies.

When you see the yeast at near the end of high krausen in the starter, you can refrigerate it, this will prevent the starter from hitting terminal gravity. It's good to leave a little food for the yeast during the chilling phase of the starter. Most yeasts will flocculate (drop out) within 48-72 hours so it can be decanted prior to pitching. Try to make your starter as close as you can to brewing day for a better yeast health and fermentation. Fresher yeast makes better beer.

This makes the most sense. I think what I and maybe the original poster are trying to figure out is how do we determine this while the starter is on a stir plate. The Krausen signs are not that obvious when a vigorous stir is in progress, much less when it's starting to wind down. On top of that we are having to make multiple starter stages. The yeast calculators say that we need on the order of 500 Billion cells. We can only get that by doing at least one decant and then re-loading with starter wort. So this process of getting to Krausen and then stopping prior to running out of food has to happen multiple times prior to pitch.

We're actually spinning this up from 7ml of frozen stock in a 15ml tube. Getting the timing right to take off of the stir plate before freezing is perhaps even more important.

There is no need to heat the yeast during propagation unless you are very low, 64F or lower is too low for most yeast. 68F (20C) is about the perfect temperature to propagate both ale and lager yeast, which nicely corresponds to room temperature for most conditions. Elevating the temperature speeds everything up, including the yeast's metabolism. This means the yeast propagate faster and degrade faster in the presence of oxygen.

The temperature to propagate at comes from an article by microbiologist Bryan at suigenerisbrewing.com (https://suigenerisbrewing.com/index.php/2022/09/20/optimizing-yeast-starters/)

pitch at high krausen (which is as the Krausen starts to collapse)
no need to decant since there is still yeast in the liquid portion
don't chill it
time your starter and brewing
if your going to used cold settled yeast just save it from a previous brew

I suspect this practice only works for a narrow range of brews. Particulary something low gravity (by comparison) and highly flavored.
My quick calculation is that throwing 3l of undecanted starter in my 1.100 Quadrupel wort would drop it down in to the 1.08's. It would dilute the wort and alter the flavor profile. Probably even more so for a barleywine.

 

[Brew Cat]

Thanks for all the replies.

This makes the most sense. I think what I and maybe the original poster are trying to figure out is how do we determine this while the starter is on a stir plate. The Krausen signs are not that obvious when a vigorous stir is in progress, much less when it's starting to wind down. On top of that we are having to make multiple starter stages. The yeast calculators say that we need on the order of 500 Billion cells. We can only get that by doing at least one decant and then re-loading with starter wort. So this process of getting to Krausen and then stopping prior to running out of food has to happen multiple times prior to pitch.

We're actually spinning this up from 7ml of frozen stock in a 15ml tube. Getting the timing right to take off of the stir plate before freezing is perhaps even more important.



The temperature to propagate at comes from an article by microbiologist Bryan at suigenerisbrewing.com (https://suigenerisbrewing.com/index.php/2022/09/20/optimizing-yeast-starters/)


I suspect this practice only works for a narrow range of brews. Particulary something low gravity (by comparison) and highly flavored.
My quick calculation is that throwing 3l of undecanted starter in my 1.100 Quadrupel wort would drop it down in to the 1.08's. It would dilute the wort and alter the flavor profile. Probably even more so for a barleywine.

it is not going to dilute it that much because your not calculating in the gravity of wort of the starter and the fact that that starter wort still containes fermentables
I seriously doubt that would be noticable in anything other than a math calculation

 

[Hawkbox]

Their methods are probably the best, I generally give it 2 days, then let it settle, pour off whatever I don't want and then dump half into a jar and half into the fermenter.

 

[Brew Cat]

this is an argument that will never be settled no right or wrong
If your that worried about dilution Pour half off and brew with a quart less water
I would still pitch that before it settles for the benefit of no fermentation lag
especially with a high gravity beer which I would think is more vulnerable to contamination sitting than a lower gravity beer

 

[Ozarks Mountain Brewery]

when the foam completely disappears

 

[HighVoltageMan!]

The Krausen signs are not that obvious when a vigorous stir is in progress, much less when it's starting to wind down.

The key is to get enough healthy yeast to pitch. You may be able to optimize the process, but you may be making the process more difficult. If the stir plate is kept at a lower speed, most yeast form a visible krausen, as the krausen collapses is when the available carbon or food source is being reduce. Theoretically, you may be able to grow more yeast by spinning faster, but you will also make it more difficult to gauge the progression of the propagation with the krausen level. The main point of stirring is to create agitation to drive off the co2 and introduce small amounts of oxygen. Yeast growth is inhibited by the co2 in solution.

The amount of growth from the starter is also a factor. Typically for most homebrewers, the rate of growth or multiplication of cells is 6-20 times, sometimes higher and sometimes lower. If you have a 1 liter starter with a inoculation of 10 billion cells, the typical growth will be to roughly 140 billion cells, I have found this can take 12-20 hours to hit high krausen. It's really hard to increase the cell count beyond a certain point, because the media because "saturated" so to speak. The yeast cells will hit maximum density and stop reproducing. That same 1 liter will an inoculation of 100 billion cells may only produce 200 billion cells or so and hit high krausen in about 2 hours.

I go by the seat of my pants and run with experience, because I'm just a homebrewer. The krausen, the color of the starter (it looks creamier as more yeast are produced) and time are the 3 things I look for. If I were doing this in a professional environment, I would keep track of the gravity in the starter and crash cool within 1-2 plato of terminal.

We're actually spinning this up from 7ml of frozen stock in a 15ml tube. Getting the timing right to take off of the stir plate before freezing is perhaps even more important.

With that small of inoculation, it would be very important to start small and build up. 100mL first, then to 1 liter then whatever you going for. Most propagations are increased each time by a factor of 10 in volume (You probably knew that already).

I have preserved yeast with the home cryogenic method and it work at first, but after 6 months in storage the beer brewed with it wasn't very good. The yeast spun up fine and the fermentations seemed good, but the off flavors in the beer were apparent and it had vegetal note. I suspected the yeast drifted genetically over time. I have not done it since.

The temperature to propagate at comes from an article by microbiologist Bryan at suigenerisbrewing.com

I would be hesitant to push the temperature of the starter above 70F. Yeah you can get faster growth and maybe even higher cell counts, but it brings some troubles with it. The higher temperatures can produce petite cells and if your controller gets away from you, you can actually kill cells. There is lot of good advice on the website for sure, but I would shy away from that practice.

High levels of FAN help not only with cell counts, but also health. Most beer fermentations start with 150-170ppm of FAN. Some studies have shown that yeast used up 80-100ppm of FAN in normal wort. When the levels in the starter go to 400ppm, the FAN levels will drop to 200ppm, meaning the yeast used more nitrogen and create more biomass. More cells and healthier cells. With that much FAN in the starter, decanting becomes more important.

If you are going to try to freeze the yeast, it would be better to error on the side of caution and get it off the stir well ahead of terminal gravity. Put it into the refrigerator and collect a smaller, but healthier amount of yeast.

Sorry to be so long winded, but this sort stuff fascinates me (NERD!). I think what your doing may not turn out like you plan or want, but you're going to build a better understanding of yeast and beer. Brew on!

 

[Brew Cat]

you are long winded
but that's ok
personally I rather brew beer so if Im using liquid yeast I just pitch 2 packs
if I was doing the above barley wine Id do that on a cake

 

[Dave Y]

I routinely do starters, a lot of times I buy yeast in batches of several and they may not get used right away. I have not pulled at high krausen though and have been pulling the sample later, with the spinner going the whole time. I definitely get good results almost all the time. I will adjust the process the next time out though.

 

[Ozarks Mountain Brewery]

actually last year I bought 4 bricks of dry so I dont use a starter right now