Overbuilding Imperial yeast starter

[happyduke]

HI,
I'm just starting with the starter overbuild method so maybe it's a silly question but how much should I overbuild? I've read that it's 100 billion cells but Imperial yeast has initial count of 200 billions, so should I overbuild 100 or 200 billions? Thanks!

 

[McMullan]

By 'overbuilding a starter' do you mean to hold some back (for a future batch) or pitch at a decent rate?

 

[happyduke]

To hold some back for a future batch, yes.

 

[tracer bullet]

It depends on how many gallons you want to ferment and what OG it is. I'd start by looking at one of the calculators, Brewer's Friend as an example. It'll give you an idea of how many cells would be recommended and also what you can expect from various starter methods and volumes.

In other words - you haven't really given enough info for a recommendation.

 

[happyduke]

Sorry, let me clarify. I do use a Brewfather calculator, it's actually the reason why I have this question

So here's what I've got

So I'm just trying to understand what should be my overbuild count if the original yeast package got 200 billions. Should I overbuild 100 or 200 billions? Or maybe the original cell count doesn't matter at all? Sorry again if it's a stupid question

 

[McMullan]

To be honest, unless you're going to be pitching it within a few days, maybe a week or so, I don't really see the point in holding back too much, as you're always better off making a starter and pitching freshly prepped yeast. You're much better off storing a small (ml) amount for any length of time and stepping up when required. That way you get the full benefit of your efforts, rather than allowing them to tick down between brews, based on questionable advice. Yeast viability remains higher for longer when stored at low cell densities. A few ml stored in the fridge is going to remain viable for at least a year. If I were going to be using the yeast within a week, I'd repitch yeast from the first decently pitched batch.

 

[happyduke]

To be honest, unless you're going to be pitching it within a few days, maybe a week or so, I don't really see the point in holding back too much, as you're always better off making a starter and pitching freshly prepped yeast. You're much better off storing a small (ml) amount for any length of time and stepping up when required. That way you get the full benefit of your efforts, rather allowing them to tick down between brews. Yeast viability remains higher for longer when stored at low cell densities. A few ml stored in the fridge is going to remain viable for at least a year. If I were going to be using the yeast within a week, I'd repitch yeast from the first decently pitched batch.

Hmmm, so my plan is to split the starter, brew on Saturday then brew with this harvested yeasts in a month or so. I will make a new starter for it and overbuild again (for the next next batch). Brewfather suggests that I should harvest 630 ml, so I was going to put it in a jar, seal and store in a fridge in low temperatures. Is this what you mean by "storing a small (ml) amount"?

 

[logdrum]

I shoot for 100-150b cells to bank for future batches in the same manner as you describe above.

 

[McMullan]

No, I'd literally store a few (3) ml or so in, say, a 5-10ml vial. What on earth is 'Brewfather' basing these recommendations on? BS?

 

[happyduke]

No, I'd literally store a few (3) ml or so in, say, a 5-10ml vial. What on earth is 'Brewfather' basing these recommendations on? BS?

I don't know but it seems to be a common practice, at least Brulosophy article implies that – Yeast Harvesting

 

[bjhbrew]

Yep, what you propose is very common (overbuilding and storing a portion of a yeast starter). I always aim to overbuild by 100b and end up storing it in a mason jar in the fridge.

 

[McMullan]

Common practice doesn't make it good practice, even when it's presented as pseudo science to the masses. Most people are reluctant to admit they got something wrong, especially online. An unfortunate reality in psychology. Most have nothing to compare with. Just a belief it works. Until it doesn't. When the blind lead the blind, both shall fall into a ditch

 

[happyduke]

Huh Ok, pseudo science or not but I'm honestly not getting how I can grow something out of 3 ml yeast + wort.

 

[bjhbrew]

Well op, you’ve got a couple different opinions. I hope mcmullan will explain why he’s strongly against the overbuild process because I think that’s the first time I’ve heard someone advocate against it. I assume you’re still planning to have an adequate pitch rate to go into your main batch, I don’t see a problem. Anyway, see ya in the ditch.

 

[McMullan]

Huh Ok, pseudo science or not but I'm honestly not getting how I can grow something out of 3 ml yeast + wort.

No, don't use all 3ml at once. Just a tiny drop into 10ml sterile (or double boiled) wort. Then step up 5-10X (100ml, 500ml, 2500ml, and so on) every 48 hours. The end result's comparable to grabbing a few packs of the freshest yeast straight off a production line. You can't buy that. And nothing really compares with it, except grabbing a few packs of the freshest yeast straight off a production line. Do a comparison yourself. 'Overbuilding' vs stepping up from 10ml. Don't take my word for it. I'm not selling anything therefore have no need to BS.

 

[happyduke]

No, don't use all 3ml at once. Just a tiny drop into 10ml sterile (or double boiled) wort. Then step up 5-10X (100ml, 500ml, 2500ml, and so on) every 48 hours. The end result's comparable to grabbing a few packs of the freshest yeast straight off a production line. You can't buy that. And nothing really compares with it, except grabbing a few packs of the freshest yeast straight off a production line. Do a comparison yourself. 'Overbuilding' vs stepping up from 10ml. Don't take my word for it. I'm not selling anything therefore have no need to BS.

Oh, ok, now it makes much more sense to me, thanks. It does seem much more complicated, though. And how do you compare your cell count eventually? I mean you can't just keep stepping up forever

 

[McMullan]

Well op, you’ve got a couple different opinions. I hope mcmullan will explain why he’s strongly against the overbuild process because I think that’s the first time I’ve heard someone advocate against it. I assume you’re still planning to have an adequate pitch rate to go into your main batch, I don’t see a problem. Anyway, see ya in the ditch.

My option isn't based on an opinion. It's based on a microscope and several years observing fermentation performance and the quality of the end product. Confirmed over and over. No need for opinions or secondhand assumptions propagating lore. My option isn't about guessing how long a piece of string is, based on assumptions what the ends might look like. Sure, you might be able to tie a knot, but what are you comparing it with? What you find acceptable? My fermentations are typically done in a few days. How long do yours take?

 

[rtstrider]

The best bet here would be to plan this out for a lower gravity brew imo. Something in the 1.040-1.045 og range. Build a 2L 1.040 starter and save a half liter prior to pitching. I like using that method and then banking it in the freezer with glycerin and such. That nets around 10 15ml test tubes worth of yeast. You have 10 batches worth of yeast, after building the slurry back up with stepped starters, and by the time they're built up it's a nice hefty slurry! That's actually worked out significantly better than storing slurry in the fridge from my personal experience. My fermentations have been much healthier and cleaner to boot.

 

[McMullan]

Oh, ok, now it makes much more sense to me, thanks. It does seem much more complicated, though. And how do you compare your cell count eventually? I mean you can't just keep stepping up forever

I use a microscope, if I want to know exactly, but there's only so many pairs of shoes you can fit into a shoebox.

 

[IslandLizard]

The bigger question is, do you have a 2 liter flask and a stir plate?
The scenario above even demands a 5 liter flask for ~4 liters of starter.

IME, a pitch rate of 0.75 is plenty for a 1.063 Ale, so a 1.6 liter starter in a 2 liter flask will work fine.

I like Brewer's Friend for having most utilities in one place, but I prefer using a different yeast calculator to clearly see where all the numbers are and what they yield:
BrewUnited's Yeast Calculator

This will leave you 80 billion cells to ranch for a next starter batch.

 

[happyduke]

The bigger question is, do you have a 2 liter flask and a stir plate?
The scenario above even demands a 5 liter flask for ~4 liters of starter.

IME, a pitch rate of 0.75 is plenty for a 1.063 Ale, so a 1.6 liter starter in a 2 liter flask will work fine.

I like Brewer's Friend for having most utilities in one place, but I prefer using a different yeast calculator to clearly see where all the numbers are and what they yield:
BrewUnited's Yeast Calculator

View attachment 750047

This will leave you 80 billion cells to ranch for a next starter batch.

Yes, I did buy 5L flask specifically for that cause and I also have a bottle of Fermcap in case it is not enough.
Thanks for the calculator, it's very useful.

 

[IslandLizard]

No, don't use all 3ml at once. Just a tiny drop into 10ml sterile (or double boiled) wort. Then step up 5-10X (100ml, 500ml, 2500ml, and so on) every 48 hours. The end result's comparable to grabbing a few packs of the freshest yeast straight off a production line.

Did you forget to mention that this method requires a complete sterile workflow? That's much harder to achieve in a typical homebrewer's environment.

In lieu of that, yeast ranching by saving out 50-100 billion cells for a next starter seems to work very well for 99.99% of us.

 

[bjhbrew]

Thanks for sharing your workflow McMullan, my own procedures are all various amalgamations of what I see others do so I like reading other peoples processes. I can see how that would achieve a more pure pitch of yeast in this manner but I’d also be a little more concerned about my ability to keep the conditions sterile at each step. I could be wrong but my thinking is that at that cell count any wild yeast or bacteria would have a better chance at getting a foothold, I’d that true or not? One other thing I wonder, would you see more generational drift in the yeast with that many steps or is there just not the environmental pressure like in a fermenting batch of beer? Anyway, I’m intrigued but I also like the results I’m getting as is. My fermentations are quick, reach expected FG, and don’t exhibit any negative fermentation by products that I’m able to discern.

 

[palmtrees]

I overbuild all my starters and then make a new starter the next time I use that yeast. I do 2.5 gallon batches, so I typically just double the starter recommended by the yeast calculators, which is still small enough to work in a 2L flask. Then I save a little less than half of the yeast in a mason jar in my fridge and pitch the rest. I repeat that process whenever I brew. After a few rounds, I'll dump some of the yeast and start from a smaller bit of slurry to sort of get back to an original starting point.

So far, it has worked very well, and I'm getting super healthy fermentations. I don't see the point of doing five-step starters for every batch in a home brew context. That seems way more complicated than it's worth. The purpose of my process is striking a good balance between efficiency, reducing yeast costs, and upping yeast effectiveness. I'm happy with that balance for me. And I much prefer overbuilding starters to collecting yeast from the fermenter because I don't have to think about the type of beer the yeast just fermented and how that might affect their next fermentation.

 

[McMullan]

Did you forget to mention that this method requires a complete sterile workflow? That's much harder to achieve in a typical homebrewer's environment.

In lieu of that, yeast ranching by saving out 50-100 billion cells for a next starter seems to work very well for 99.99% of us.

Double boiled wort (simmered with lid on second time) is good enough generally. Pressure cooking is even better. I don't view it as a barrier for home brewers. Basic equipment: pots and jars. We've all got them. I have the luxury of use of a lab equipped with an autoclave and laminar flow hood. For home brewing I generally choose to work in the kitchen using a pressure cooker for the 10ml aliquots and oven to sterilise 10ml to 5000ml bottles. Subsequent step ups, starting at 100ml, are double boiled kettle leftovers or mini mashes if there aren't any leftovers. You can even buy sterile starter wort in cans these days. You don't need to be a microbiologist to do this basic stuff. It's home brew, not a clinical trial. A little common sense and you're almost there. With some planning, it involves little more than pouring current into next step then repeat in two days. The end result is noticeably better. You can't beat freshly prepped yeast. I've just pitched some. I poured off the spent wort and replenished with oxygenated sweet FV wort to resuspend the yeast cells before pitching into the FV. As soon as they came in contact with the fresh wort they started 'fizzing' immediately. You simply don't get that kind of biological response with yeast that were prepped weeks ago. Have a go at it - you have something to compare it with. Others will claim you over pitched when the fermentation finishes in a few days and the beer turns out predictably fantastic every time.

 

[McMullan]

Thanks for sharing your workflow McMullan, my own procedures are all various amalgamations of what I see others do so I like reading other peoples processes. I can see how that would achieve a more pure pitch of yeast in this manner but I’d also be a little more concerned about my ability to keep the conditions sterile at each step. I could be wrong but my thinking is that at that cell count any wild yeast or bacteria would have a better chance at getting a foothold, I’d that true or not? One other thing I wonder, would you see more generational drift in the yeast with that many steps or is there just not the environmental pressure like in a fermenting batch of beer? Anyway, I’m intrigued but I also like the results I’m getting as is. My fermentations are quick, reach expected FG, and don’t exhibit any negative fermentation by products that I’m able to discern.

I'm not sure what's meant by 'generational drift'. You'd have to put the yeast through a very narrow bottleneck (e.g. a single cell/colony) to achieve something like that genetically. Quite a random process even then. A lottery. I think 'generational drift' is more likely to do with yeast getting 'sick' in the fridge, waiting for weeks to be pitched.

 

[hottpeper13]

On that yeast calculator screen shot it shows a 2.3 growth rate. The most viable yeast according to Chris Whites book has a growth rate between 3 and 5. My way is to loop some saved yeast into a 15 ml tube then into 150 ml then 1500,always X10, that gives a 3-5 growth rate.

 

[IslandLizard]

On that yeast calculator screen shot it shows a 2.3 growth rate. The most viable yeast according to Chris Whites book has a growth rate between 3 and 5.

I don't think viability is being tested there. If you simply increase the starter volume to 2 liters (from 1.6) and the gravity to 1.040 (from 1.037), grow rate will be 3.1.

I just put that out as an example for the OP on how to get a very workable pitch rate (0.75 million cells/ml) and a decent amount of surplus to be ranched, in one single step in a 2 liter flask.

The maximum usable stir volume in a 2 liter flask is about 1.8 liter, while starter gravity is a bit arbitrary, so there's some leeway.
I've been making starters similar to this for almost 8 years with very few problems. And got better and swifter at it over time.

 

[renstyle]

Had a related question looking to overbuild some Wyeast 2001 Urquell for an upcoming BoPils.

This well known calculator specifies 1.5 million/mL yeast density for a lager.

However, I will be pressure fermenting with a keg in the ale temp range (18-20C/65-68F), spunding at around 12 PSI.

Since alot of the growth rate of yeast is dependent on temperature, I was thinking that I could use the Ale calculations (0.75 million/mL) rather than the lager to base my calculations on for my overbuild.

Just doing a sanity check on my logic, making sure there wasn't something else obvious I was overlooking.

 

[IslandLizard]

Had a related question looking to overbuild some Wyeast 2001 Urquell for an upcoming BoPils.

This well known calculator specifies 1.5 million/mL yeast density for a lager.

However, I will be pressure fermenting with a keg in the ale temp range (18-20C/65-68F), spunding at around 12 PSI.

Since alot of the growth rate of yeast is dependent on temperature, I was thinking that I could use the Ale calculations (0.75 million/mL) rather than the lager to base my calculations on for my overbuild.

Just doing a sanity check on my logic, making sure there wasn't something else obvious I was overlooking.

I think that should work fine, due to fermenting at higher temps, and thus at higher pressure to reduce high temp fermentation side effects.
Let us know how it worked out, I'm curious about fermenting Lagers that way. You may save a week in fermentation time, although you'd still need to give her ample time for lagering to clarify.

Brülosophy did a Lager yeast exbeeriment on over/under pitching. The only problem I have with that test is he didn't provide a comparison with a properly pitched batch. Probably because he's not set up for fermenting a 3-way split batch under the exact same conditions.
https://brulosophy.com/2016/11/07/y...-vs-overpitch-in-a-lager-exbeeriment-results/